ARPIE - MIDI Arpeggiator Kit
ARPIE
ARPIE
ARPIE - MIDI Arpeggiator Kit
ARPIE
ARPIE

ARPIE Full Kit

£79.00

MIDI Arpeggiator Kit

ARPIE is a compact, highly-functional, MIDI arpeggiator that comes as a DIY kit.

As you are looking at this, it is likely you already know what an arpeggiator is, but if not here is a quick description… An arpeggiator is a device which takes chords (maybe played on a keyboard) and converts them into rapid sequences of notes, which can then be played through MIDI-compatible synthesizer hardware or software. Arpeggiation is a very common technique in electronica and chiptune music and is an excellent creative technique. You should note that ARPIE does not make any sound by itself, but rather outputs MIDI note information which can play a synth, sampler, software synth or other compatible sound module.

ARPIE’s Hardware and firmware are open source, and firmware is based on Arduino, making it easily hackable. The feature list includes

  • Arpeggiate Up/Down/Up-Down/Randomised/Manual or play all notes in polyphonic gated chord mode
  • Mutate and extend the arpeggio with inserted notes: None/Lowest note/Highest note/meander 3 steps forward 1 step back/4 steps forward 2 steps back
  • Force arpeggiated notes to a musical scale: 7 musical modes/11 root notes/selectable out-of-scale note handling
  • Extend input chord over 1-4 octaves
  • Control playback rate: 1 beat per step thru to 1/32 beat per step, including dotted and triplet time options
  • Control note length and MIDI velocity
  • Transpose up or down by 1-3 octaves, by -3 thru +12 semitones from front panel, or by any pitch via MIDI input note
  • 1-16 step play/rest pattern (selected steps played or muted) with randomisation option
  • The transpose sequencer feature automates up to 16 bars of transposition. Combined with the force to scale option this is awesome for finding new chord progressions and creating entire songs.
  • Manual chord entry (note toggle) mode. Experiment with chords and access ARPIE’s full potential without any keyboard attached!
  • Per-step Accent, Full Gate, Tied Gate, Octave Up/Down, Fourth interval down, Play Through (Play notes together polyphonically) with randomisation options
  • With optional CV TAB daughter board sold separately supports CV/Gate out with per-step pitch glide and 1V/oct and Hz/V pitch scaling. CV TAB also adds ability to save and recall up to 16 patches – snapshots of the ARPIE chord and settings
  • Selectable MIDI transmit/receive channel + OMNI receive mode + MIDI thru + MIDI panic + MIDI “Channel Mode” message filter
  • Ability to send MIDI LOCAL ON/LOCAL OFF message to use ARPIE as an outboard arp for a keyboard synth (as long as the synth supports LOCAL OFF switching via MIDI CC#122)
  • Configurable Accent velocity level with special support for Volca FM velocity controller
  • Internal MIDI clock with BPM select and tap tempo/send master clock/slave to clock input
  • Clock input from main MIDI input or separate dedicated MIDI clock input socket
  • Manual stop/start/continue play options when slaved to external MIDI clock
  • MIDI lock mode ignores note input and thru input to output in MIDI lock mode
  • 6 pin “Hack Header” expansion port breaks out power and four GPIO lines.Standard firmware allows three standard potentiometers to be wired up to hack header and configured to control MIDI CC’s, Mod, Bend, BPM, Velocity etc
  • Three standard 5-pin DIN sockets for MIDI IN, MIDI OUT, SYNC IN
  • Receive, Transmit, Beat Clock and Chord Hold LEDs on control surface, firmware diagnostic/power LEDs on main board, reset button.
  • Integral 9V PP3 battery holder and 9V DC socket (2.1mm barrel) which works with either polarity plug.
  • Small size (98mm x 87mm x 35mm approx dimensions) and light weight (approx 125g without battery)

Soldering is required to complete this kit. Surface-mounts will be pre-soldered so you will only need to fit the through-hole components.

Case must be purchased separately

Fascia Colour Preference

White PCB, Black PCB

ARPIE USER GUIDE

KIT CONTENTS

This page shows the contents of the ARPIE standard kit. Please note some items may vary in appearance from the photographs below


Note: The control surface PCB has two pre-soldered SMT ICs and two 0805 capacitors on the reverse side

Note: If you have the newer Revision 3 PCB you will have, in addition to the above, another three 1N4001 diodes (total of 4) and an additional 6 way female pin header strip.

Note: The high-brightness blue LEDs in current kits look different to the above (have a blue lens)


Note: Current kit comes with 13 of these switches plus one 90 degree switch

PCB Footprint for battery box is based on TruPower BH-9VP

BUILD INSTRUCTIONS

When soldering a PCB, it generally helps to solder lower height components first. This stops the taller components getting in the way while we are working, and it lets us hold components in place for soldering by turning the board upside down on a flat surface and letting gravity be our third hand!

We will start with the base PCB (Printed Circuit Board), as shown below

Lets solder resistors R1, R2, R3 and R4. These are 220 ohm resistors which have a colour code of red-red-brown. In your kit the tape holding each set of resistors has been labelled with the resistor value.
Lets start by separating the four resistors from their tape and bending the legs as shown

Take a 220 ohm resistor and pass the legs through the holes in the board for resistor R1 (Resistors do not have a specific polarity and can be soldered “either way round”).

Push the resistor flush to the board and bend the legs out slightly to hold it in place while you turn the board over to solder them.

Before you start soldering, make sure the tip of your iron is clean and up to temperature. Melt a little solder on to the tip to “tin” it. Use a soldering sponge or wire wool tip cleaner to remove excess solder leaving a thin bright silvery coating on the tip.

Bring the tip of the iron to where the leg of the resistor emerges from the hole and, at the same time, bring the end of your solder wire to where the iron tip,resistor leg, and PCB hole all meet each other. Don’t melt the solder directly on to the tip of the iron but rather melt it at the point where the iron tip touches the component leg. This should not longer than about 2-3 seconds. After applying the solder, remove the solder wire and continue to apply heat to the joint for about 1 second. You should see that the molten solder gets “sucked” into the plated PCB hole, forming a good connection. Now remove heat and allow the joint to cool naturally for a few seconds (don’t blow on it). The final joint should be bright and shiny, not dull or grey.

Use your wire wool tip cleaner or sponge to keep the tip of the iron clean. Clean excess solder from the tip every time you make a solder joint and re-tin it frequently. A clean, well tinned tip is the key to making good consistent solder joints.

Lets continue solder all the resistors that are fitted flat to the board. These are

  • R1, R2, R3, R4 – 220 Ohm (red-red-brown code) resistor
  • R5, R6, R7, R8 – 1.5 kOhm (brown-green-red code) resistor
  • R9, R10 – 10 kOhm (brown-black-orange code ) resistor
  • R11, R12, R19, R20 – 1 kOhm (brown-black-red code) resistor

Your board should now look like this

Now lets add the 1N4148 small signal diodes, D1 and D2. These have tiny orange and black glass packages. There is a black stripe on the cathode end which aligns with the stripe shown on the diode symbol on the board.

Unlike resistors, diodes DO have a polarity and need to be soldered a specific way around. Both the diode and the symbol representing its location on the PCB show a thick line marking one end of the diode (the Cathode)

Solder the diodes as you have resistors. Please note that diodes are a bit more heat sensitive than resistors – so don’t cook them too long with the iron!

Next we will add the crystal (X1) and the two 33pF ceramic capacitors C5 and C6 (These are marked with the code “33”)

Solder the four 100nF ceramic capacitors (C1, C2, C3, C4). These have a “104” code.

NOTE: An additional 100nF capacitor is provided that can optionally be soldered into position C9. This capacitor allows certain types of programmer to automatically reset the microcontroller for firmware uploads (so the RESET button does not need to be pressed manually). However not all programmers implement auto-reset and those that do can reset the microcontroller at inopportune times (such as when another USB device is plugged in to the computer). If in doubt, leave C9 off the board… you can always add it later.

Next we’ll solder the power switch. I recommend placing it in the holes and turning the board upside down on a flat surface so that the weight of the board holds the switch in place. Solder just the middle pin, turn the board back over and ensure the switch is flush to the board and parallel to the edge (if not, re-heat the joint while pressing the switch down to the board). Finally solder the remaining 2 pins.

Now we will solder the diagnostic LEDs (LED1, LED2, LED3) to the board. I used green LEDs on the base board and red LEDs on the control surface but feel free to mix and match the red and green LEDs as you like (but I advise against mixing them with the blue LEDs since those have quite different characteristics).

LEDs have two legs, one of which is longer than the other. The longer leg is the anode (+) terminal.

Note the symbol printed on the PCB clearly marks which hole is for the anode (+) leg. Like other diodes, LEDs do have a polarity and will not work if they are soldered in the wrong way around. They will also be a bitch to desolder, so make sure you get them right first time 🙂 Once again avoid cooking LEDs for too long as they can be damaged by excessive heating.

Solder the LEDs nice and flush to the board as shown.

Now we will add the IC (integrated circuit) sockets. These have a little notch at one end which indicates “this way up”. You will also see the IC symbol on the board show a similar notch marking. Place the socket in the holes, aligning the notches. Strictly speaking a socket will work either way round, but the notch is a convention, there to help you when you come to insert the IC’s into the sockets.

I recommend fitting the IC sockets one at a time. Turn the board over and solder two opposite corner pins of the socket. Now check the socket is flush against the board (you can re-heat the solder and press down if you need to adjust it). Once the socket is flush on the board, solder the remaining pins.

Solder the three 8 pin sockets and the large 28 pin socket. Note that sockets are not strictly essential since we could solder the ICs directly to the board. However sockets allow us to easily replace an IC and also save them from the soldering heat (IC’s can be heat sensitive). Since IC’s tend to be the most expensive and sensitive components of a circuit, it is always a good idea to invest in sockets for them.

We still have some resistors to solder. We have left them until now because we will solder them in a vertical arrangement. The remaining resistors are

  • R18 – 220 Ohm (red-red-brown code) resistor
  • R13 – 10 kOhm (brown-black-orange code ) resistor
  • R14, R15, R16, R17 – 1 kOhm (brown-black-red code) resistor

In the very latest PCB version there is an additional 1.5 kOhm resistor, R21. Leave the R21 location empty when you build the kit. Do not add R21 unless you experience problems with step LEDs flickering or lighting up dimly when they should be off (this is unlikely with the standard LEDs provided with the kit). It is very unusual that this extra resistor is needed – if in doubt just leave it off. Contact me if you need more explanation.

We prepare them by bending one leg as shown below

Use the outlines printed on the board as a guideline to put the longer leg through the hole marked for the body of the resistor as shown below.

The component outlines alternate the orientation of each vertical resistor. This helps prevent the legs of the resistors touching each other.

Now we’ll solder the transistor TR1. This is a small black component with three legs, and a D-shaped case, which helps us to correctly orient the legs. Start by slightly bending out the centre leg as shown.

The symbol on the PCB aligns with the D-shape package. Make sure you align it correctly – a transistor has a polarity and won’t work if soldered in the wrong way around.

The transistor will stand a few mm above the board when soldered. Avoid overheating the transistor when soldering it.

Add the 6 pin serial programming header (You may need to separate this from the 6-pin socket in the kit). This is placed in the set of holes marked “Serial Prog” near LED1 – please ensure you place it in the correct location as it will be difficult to move it later!)

Again it helps to invert the board and let its weight hold the strip in place while you solder one pin, ensure it is straight, then solder the others.

Now solder the reset switch making sure it is flush to the board (once again it helps to start by soldering just 2 opposite corner legs then checking position and adjusting if needed before soldering the other legs)

Next up, its the two electrolytic capacitors (C7 and C8). These have a specific polarity to observe. The anode (+) is the longer leg and also the capacitor package has a white band marking the cathode.

The symbol on the board indicates the anode hole with a + symbol.

Next we’ll solder the 20 way socket (you may need to separate this from the 20 pin header in the kit) and the 6 way socket. Again it helps to use gravity to hold the parts in place while soldering. Note that the 6 way socket is placed in the socket beside TR1, labelled “GND/PC5/PC4…”

Now solder the four 1N4001 rectifier diodes D3, D4, D5, D6. Bend these like we did with the vertically mounted resistors. To match the photograph, locate the silver anode stripe on the body of the diode, then bend the leg on the opposite end, so we can mount the stripe flush against the board as shown below. All four diodes have the same orientation and they must be soldered the correct way around. WARNING: You can damage your kit and/or DC power supply if you solder any of these four diodes the wrong way around!

Now solder the DC power socket, starting by soldering just one pin then checking and adjusting the position before soldering the remaining two pins

Place the 3 MIDI sockets in their holes and turn the board over. Start by soldering just the pins that are closest to the edge of the board, so you can ensure it is flush to the board (Its important the the sockets are flat to the board to reduce strain on the solder connections when plugging/unplugging cables). When you are happy the sockets are flush, solder all remaining pins.

Now add the voltage regulator. This part must be soldered the right way around. The metal tab lines up with the marking on the board as shown in the photo below.

Fit the battery holder, passing the M2.5 bolts through the holes in the battery holder and corresponding holes in the board.

Fit nuts to the bolts and tighten before soldering the battery connections and trimming the legs

Now the fun starts! Our first sanity check is to insert a battery and ensure the power LED lights when we turn the slide switch on

Before we insert the ICs it is good to check the supply voltage to each. If you have a voltmeter, check the voltage between each pair of points shown below. Red is positive, Green is ground. In each case the voltage should be 5V when the battery power is on. You may see a small variation (e.g 5.02V) which is not a concern.

Turn off the power and carefully insert the PIC microcontroller (IC2) into its socket. Pay special attention to the notch on the end of the package, which should align with the corresponding notch on the board and socket. Switch on the power. LED2 next to the IC should blink rapidly 3 times, then settle into a cycle of one blink every 2-3 seconds.

Turn off power and insert the ATMega microcontroller (IC1) and the two 6N138 opto-isolators (IC3, IC4). The opto-isolators may have a “dimple” on their case in place of the the notch. Align the dimpled end of the IC with the notched end of the socket.

Turn on the power. LED1 should start a steady blinking. LED2 should blink as before.

Now use four M3 bolts to attach the four 25mm threaded pillars to the four corners of the board

Attach the rubber feet to the underneath of the board as shown. These are important to stop ARPIE scratching surfaces on which it is placed.

And so, on to the control surface! You will notice the the underside of the control surface board contains two pre-soldered surface-mount ICs and two small surface-mount capacitors. If these are missing or damaged let me know!

Turn the board over and start by inserting the sixteen 6x3mm tactile switches

Turn over the board and solder a single pin of each switch. Ensure that each switch is completely flat against the board before soldering the second pin. Re-heat and press down with a thumb if you need to re-seat a crooked switch.

Now insert the 6x6mm tactile switches in their holes

Turn the board over and solder two opposite corners of each switch. Again the idea is to hold the component to the board while still giving us an opportunity to adjust it before we solder the other two pins and commit ourselves. Getting components totally flat to the board gives them mechanical stability and just looks a hell of a lot better!

After switches are completely soldered, use side cutters to trim the legs nice and short

Now insert the blue LEDs in the holes. PLEASE remember to check the polarity carefully. The longer LED leg is the (+) terminal and should pass through the hole in the board labelled +

I suggest that you bend the cathode LED flat to the back of the board while you solder the anode

Then trim the anode leg. Before you solder the cathode leg check the LEDs are flat to the board. WARNING: Getting the blue LEDs aligned consistently and flush to the board is probably the most important thing for making your ARPIE look cool vs it looking a bit of a mess! It is really worth spending time on this part. Believe me I speak from experience :-

When the blue LEDs are soldered, add the four red indicator LEDs (or green if you took that road)

Now the exciting bit.. start the drum roll… insert the 20 way long pin header strip into the socket on the base board. Orient it so the plastic support strip is at the bottom and push it down as far as it will go.

Place the control surface board on top of the standoff pillars so that the 20 way pin header emerges through the set of holes in the lower right of the control surface

Insert two of the M3 bolts to hold the board in the correct orientation

Solder the pins from the top and trim the excess legs with side-cutters (Wear eye protection – those bits of legs fly off like bullets!)

Turn on the power – after a couple of seconds boot-up time, the blue LEDs should light up. This is a good time to ensure the LEDs are straight. If not you might still be able to reseat them with patience and care, but be careful of overheating the LEDs.

And finally – we are done. Get some MIDI gear plugged in an make some sounds!

Diagnostics & FAQ

OK I built it – so what now? How do I know if its working?

If you wish to run on a PP3 battery: Insert the battery and ensure nothing is connected to the DC input socket.

If you wish to run on a DC suppy: Ensure the supply is a centre-positive 2.1mm barrel with a voltage of between 7 and 24V

Switch on power using the slide switch on the left edge of the lower board. Slide the switch towards the back to switch on.

  • Power indicator LED3 should light immediately
  • Within a couple of seconds all blue LEDs should illuminate and the CLK indicator LED should start blinking
  • Diagnostic indicators LED1 and LED2 on the lower board should blink occasionally
  • Press each of the data buttons below the blue LEDs in turn (don’t press any other buttons yet). You should be able to toggle each blue LED on and off by pressing the button below it.
  • Press and release the HOLD switch. The HOLD LED should toggle on and off.
  • Switch HOLD on and press the INST switch. The display on the blue LEDs should change so some LEDs are off some are dimmer or brighter than usual. Within a couple of seconds of pressing INST, press the data button below rightmost LED. The TX button should start blinking.
  • Press each menu button PLEN, MODE, SHFT, SPAN, RATE, VELO, GATE, INST, SYNC, CHAN, TRAN in turn. Each time you press a button the display on the blue LEDs should change.
  • Press PLEN then PATN – pressing PATN should toggle back to the default display

If all the above tests work, things are looking pretty good! Now we just need to check out the MIDI side of things…

  • Connect a MIDI keyboard to the DIN socket below the RX (receive) LED.
  • Ensure HOLD is off and press some keys on the MIDI keyboard. Assuming the keyboard is configured to send MIDI notes, and it is connected correctly, the RX light should blink as notes are pressed and release. While notes are held, the TX light should blink and the pattern display should show a moving pointer (brighter blue LED)
  • Connect a synth or sound module to the DIN socket below the TX (transmit) LED. Assuming default settings, ARPIE transmits on channel 1, so make sure you are set up to receive on this channel.
  • Hold a chord on the MIDI keyboard and ARPIE should arpeggiate this to the synth

All good? Excellent. The one last test is of the MIDI synch input (the DIN socket below the CLK LED)

  • Connect a device which can send MIDI synch to the CLK socket on ARPIE and ensure the device is set up to send MIDI clock messages.
  • Hold down the SYNCH button for 5 seconds. Ensure the fifth blue LED is showing brightly on. If not, press the button below it to toggle it (default settings will have this setting on). Wait a few seconds for ARPIE to revert back to the main display
  • Press SYNCH again and now press the button below the leftmost LED. The LED should light brightly and the CLK LED should stop blinking
  • Now start up your MIDI clock source device. ARPIE’s CLK LED should blink while the external clock is running and stop when it is not running

If all the above works – congratulate yourself – you just built your own MIDI arpeggiator!

No activity. Power LED (beside the power switch) does not come on

  • If you are running from a battery, check that a DC adaptor is not plugged in. The DC supply socket disconnects the battery when a plug is inserted, even if the DC supply is off.
  • If you are running from DC supply ensure that the polarity is centre positive and the voltage is at least 7 volts.
  • Check that diode D3 is soldered correctly
  • Ensure the switch is power switch is soldered properly and is fully slid to the ON position

Power LED is on but nothing is working

  • check whether diagnostic LED1 and LED2 are flashing. If not, check the orientation of voltage regulator IC5 and electrolytic caps C7 and C8.
  • Use a voltmeter to check between the ground (centre) and output (closest to C2) pins of IC5 which should read 5V. Check the voltage between ground and IC5 input (closest to C1). This must be at least 7 volts for the regulator to function correctly.
  • If at least 7V is present on regulator IC5 input, but no voltage (or much less than 5V) on the output, suspect the regulator. Check orientation, solder joints etc. Replace regulator if needed.
  • Remove IC1,IC2,IC3,IC4 from the sockets and check the voltage present on the socket pins as described in the build instructions. If any voltage is missing, re-check solder joints and PCB tracks. Check for solder bridges (solder blobs shorting between pins or tracks)
  • Microcontrollers IC1 and IC2 are programmed to flash diagnostic LED1 and LED2 periodically to show they are alive. If the correct supply voltages are present, but one or both diagnostic LEDs do not light, check the LED orientation (and if possible check the LED with diode test function of a multimeter) to ensure the LED is healthy before suspecting the microcontroller. Please contact me if a microcontroller IC appears to be dead and we can try further diagnostics before deciding if a replacement is needed. All MCUs are tested before packing the kits, but they can be damaged by reverse/over voltage supply or by static electricity discharges.

No blue LEDs on

  • Check the connector joining the top and bottom boards is inserted correctly into its socket (It is possible to accidently insert just one row of pins, with the other row overhanging the socket. Check you have not done this)
  • Check solder joints on the plug and socket
  • Check TR1 is oriented correctly
  • Re-check solder joints
  • Replace the transistor

Individual Blue LED does not come on/comes on dim

  • Check the solder joints on the LED
  • Check the orientation of the malfunctining LED (The circular outline of LED bulb actually has a flat edge to mark the negative cathode). The cathode for each blue LED should be at the top (towards the back edge of the board)
  • If possible test the LED by connecting a multimeter on diode test mode directly to it to see if it lights
  • Replace the LED with an included spare
  • Check whether you also have issues with one more more of the menu switches. This could indicate an issue with a shift-register output (with one of the small IC’s on the back of the control surface PCB). Please contact me for further diagnostics in this case.

Blue LEDs flicker

  • Some flickering is normal, especially when an LED is showing a dim level. This is because the LEDs do actually flicker rapidly due to the multiplexed way they are driven. This should not usually be noticeable unless you are looking for it – or are especially sensitive to it. If this is a real problem for you please let me know – we can probably improve this by adjusting firmware settings.
  • If you are seeing erratic behaviour in general, not just with the LEDs, then check the battery is not flat, or power supply level is too low. Check solder joints and ensure the connector joining the top and bottom boards is firmly located. Ensure the IC’s are seated properly in their sockets.

All Blue LEDs are on brightly all the time and don’t react to changes in menu selection

This can be the surprising effect of a single LED being soldered in the wrong way around. Carefully check all the LEDs are oriented correctly. This might also result if an LED is failing short circuit (but in this case the faulty LED would not light up, so should be easy to locate and replace)

Additional Top Board Diagnostics

If the top (control) board is not working correctly, or at all, here are some diagnostics to try and isolate the problem:

  • If you press the HOLD button does the HOLD light come on? The HOLD feature and the other 3 red LEDs are wired independently of the shift register IC’s on the back of the control surface PCB. If none of the red LEDs are coming on but the bottom board is healthy then this suggests one of the following (a) The long pin connector is not fitted, soldered, or oriented correctly or pins need cleaning (b) The LEDs are oriented incorrectly (c) There is a break in the ground connection. To test for case (c) use an ohm meter to measure the resistance between the GND pins on the header and the (-) terminal of the battery (make sure there is not a plug in the DC socket since that disconnects the GND side of the battery).
  • There should be a low resistance (no more than a couple of ohms) between the GND pins and the battery (-) terminal when the boards are connected together. If there is a very high resistance or open circuit, check for damage between the GND pins and the PCB “ground plane” on both PCBs.
  • If there is continuity between the pin header and the battery, check between the GND pins and the switch legs to the lower right side of the HOLD button – these should be connected. An open circuit here would isolate the issue to the ground plane on the upper board. Check for PCB damage below the header.
  • Here are some tips to check the red LEDs: (a) The HOLD LED should come on when you press the HOLD button (b) The CLK LED should blink when you are using internal synch (c) The RX and TX LEDs should blink when you connect a MIDI keyboard to MIDI IN and play notes
  • The blue LEDs and the buttons (other than HOLD) are driven by the two small shift register components on the back of the board. If the blue LEDs are not working, it is difficult to know if the buttons are working or not, but this is important to help us isolate the issue. Here is a test we can do to see if the keyboard is working even when the blue LEDs are not: Assuming the SYNCH LED is blinking, press the SYNCH button once then press the small switch below the first blue LED. This should stop the SYNC LED blinking (as we switch off the internal synch). Repeating the same should start the SYNCH LED blinking again. You can also try changing tempo when the LED is blinking by pressing SYNC then one of the middle LEDs. If these tests work then it suggests (a) The shift registers are OK (b) The problem is with the low side of the blue LEDs, which pass through the STR pin on the header to transistor TR1 on the main board. Check PCB tracks and solder joints, including transistor TR1, Resistor R18, Resistor R11, IC socket connection for IC1.
  • Another test you can carefully do is to briefly short the STR pin to the GND pin below it, using the blade of a screwdriver. If all the blue LEDs come on brightly then this suggests the shift registers are working and the issue is either the connector or the base board (do not light the LEDs too long this way since there is no series resistor to limit the current, so the LEDs could possibly be damaged)
  • If the above tests fail then the shift registers, or the connections to them, could be damaged. These components are pre-soldered and tested before being placed into kits, so this should be less likely than issues with other components or joints. However it is worth checking that no solder debris has got attached to the legs of the shift register ICs causing shorts, and that no damage (scratches etc) has occurred to the tracks.
  • The following shows the layout of the top side of the header pins (lower right corner of control surface) as they are exposed when the boards are connected together
    CLK, DAT, KS1, LD1, LD2, LD3, LD4, STR, SW1, KS2
    VCC, VCC, GND, GND, GND, GND, GND, GND, UN1, UN2

Device does not receive MIDI notes/external synch

  • Ensure that the ARPIE input channel is set correctly
  • Ensure that controller device is set up to send notes/synch and (for notes) that the send channel on the controller matches the input channel on the ARPIE
  • The RX LED should blink as notes are received. If RX does not blink, but otherwise things seem to be working, check the orientation of the LED and if possible use a diode test mode on a multimeter to check the LED. Replace the LED.
  • Ensure MIDI lockout is not engaged (HOLD flashing). This mode causes ARPIE to ignore all input. Press HOLD to disengage, or power down/up.
  • For external synch issues, check that synch source is set to external and that the global options for synch settings are configured to use the required input source
  • Check the solder connections to the MIDI input sockets and ensure that all legs of the sockets are connected properly
  • Check opto-isolators IC3 and IC4 are oriented and inserted correctly
  • Check diodes D1 and D2 are oriented correctly
  • Check that microcontroller IC2 is inserted correctly. Diagnostic LED2 should flash 3 or 4 times on power up and should then blink periodically. IC2 is responsible for receiving the MIDI from the CLK socket.

Device does not send MIDI notes

  • Does the TX LED flash? If TX is flashing, ARPIE is trying to send MIDI data. Check the MIDI channel selected for ARPIE output matches the input channel of your synth. Check solder joints to the output MIDI socket and resistors R1-R4. Ensure IC1 is inserted correctly.
  • If the TX LED does not flash when notes are being sent, check the orientation of the LED and if possible use a diode test mode on a multimeter to check the LED. Replace the LED.

Cannot Upload New Firmware

  • Make sure you have selected board type “Arduino Duemilanova w/ATMega 328”
  • Make sure you have the correct COM port selected
  • Make sure you have the correct drivers for your USB-TTL device
  • Try closing and re-opening the Arduino environment (especially if you have just connected USB-TTL device while Arduino environment is running)
  • Try rebooting your computer (especially if you have just installed drivers for a new USB-TTL device)
  • Check wiring between the USB-TTL device and the header on the board
  • Depending on the type of USB-TTL device you may need to reset the board when the Arduino environment shows “Uploading”
  • Locate and open boards.txt (within your Arduino installation in a hardware/arduino folder)
##############################################################
atmega328.name=Arduino Duemilanove w/ ATmega328
atmega328.upload.protocol=stk500
atmega328.upload.maximum_size=30720
atmega328.upload.speed=57600
atmega328.bootloader.low_fuses=0xFF
atmega328.bootloader.high_fuses=0xDA
atmega328.bootloader.extended_fuses=0x05
atmega328.bootloader.path=atmega
atmega328.bootloader.file=ATmegaBOOT_168_atmega328.hex
atmega328.bootloader.unlock_bits=0x3F
atmega328.bootloader.lock_bits=0x0F
atmega328.build.mcu=atmega328p
atmega328.build.f_cpu=16000000L
atmega328.build.core=arduino
atmega328.build.variant=standard

In this block, if your setting of atmega328.upload.protocol is set to arduino try changing to stk500. Save the file and restarted the Arduino environment.

How do I get at the battery to change it?

You only need to remove the 4 screws holding the top PCB to the pillars. The connector can simply be pulled out of its socket allowing access to the battery holder (If connector is stiff just waggle it gently). Just take care to insert the connector pins in the correct holes when re-assembling it. Don’t de-solder anything!!

Its gone mad, changing velocity/sending mod wheel/pitch bend etc at random!!

Chances are you have accidentally enabled one or more of the “hack header” inputs. These inputs allow you to control various settings with external potentiometers wired to a header on the ARPIE board. However, without hardware attached you can see random behaviour. The solution is to turn off the hack header inputs.. Press and hold PLEN and turn LEDs 1-8 off. Alternatively do a full settings reset by holding down HOLD at power up, then pressing and releasing MODE (while HOLD is pressed)

Expansion Boards

Tabs are small expansion boards that plug into ARPIE’s hack header. Please note that only one can be used at a time.

  • CVTAB adds CV and Gate voltage outputs to the ARPIE so that it can control analog synthesizers. CV TAB also adds 16 patch memories so you can save and recall patterns
  • MEMOTAB adds the 16 patch memories without CV functionality
  • SYNCTAB is designed to allow ARPIE to both receive and send pulse clock signals, so it can synchronise with other devices that use voltage pulses for timing, such as the Korg Volca series of synth/sequencer modules.
  • CONTROLTAB is a simple module mounting three potentiometers and a switch. You can use ARPIE’s menus to configure the parameter that each of these will control (e.g. tempo, velocity, mod wheel, pitch bend)

Firmware Updates

Please Note: The ARPIE kit comes with the current firmware already loaded on the microcontrollers The information here is only needed if you want to reprogram it later with new firmware, or experiment with the firmware yourself!

The following ARPIE firmware versions are available:

  • Version 6.1
    This version adds support for the CVTAB and MEMO TAB expansion boards. See release notes for details and instructions
  • Version 5.1
    This version fixes a bug that crept in at version 5 and prevented correct operation of the Synctab add-on board 🙁
  • Version 5.0
    Adds manual chord edit, transpose sequence, additional pattern layers, accent velocity control, velocity CC for Volca FM
  • Version 4.0

The following instructions relate to the Silicon Labs CP2102 adaptor which I sell as an option with the ARPIE, however similar steps apply to other programmers (e.g. FTDI 5V USB2TTL Programming Cable).

You will need to download and install the free Arduino environment from http://arduino.cc

Before connecting CP2102 programmer you will also need to download the drivers from the following URL
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx

Connect the programmer to a free USB socket on your computer and let the drivers install.

The programmer connects to the 6 pin programming header (ICSP1) on the ARPIE main board. The CP2102 adaptor
uses a four pin lead (made up of individual 1 pin cables). These connect to pins 2,3,4,5 on the header (pin 1 is marked on the board and is the one nearest the back edge of the device

You need to make the following connections

Pin on ARPIE Pin on Programmer
[1 RESET]
[2 TX] ………. [RX] Note that RX and TX connections swap over!
[3 RX] ………. [TX]
[4 +5V] ………. [+5V]
[5 GND] ………. [GND]
[6 GND]

It might be neccessary to take out the screws and remove the top ARPIE PCB to access the programming header. The control surface does not need to be attached during programming.

Before programming ensure that

  • All MIDI leads are disconnected
  • The ARPIE is powered by DC supply or battery and is switched on (it might look powered up as soon as USB is connected but you MUST power ARPIE normally and make sure it is switched on)

When you download the firmware source code from Github, make sure you save the “Raw” file, not the HTML page where the code is viewed. Click on the “Raw button in GitHub and make sure the code is saved with a .INO extension.

Open the file in Arduino (you will get prompted that the code has been placed automatically in an “arpie” folder)

In the Arduino environment, select the COM port for the programmer (which is usually the highest numbered port and appears only when the programmer is attached) and select Board Type “Arduino Duemilanova” and processor type “ATMega 328”

Press Ctrl-U to compile the code and upload to the ARPIE. Compilation takes a few seconds – get ready to press the reset button on the ARPIE… as soon as the message on the Arduino status bar changes from “Compiling” to “Uploading”, press the reset button on the ARPIE board. Within 10-15 seconds you should have a “Done” message in the Arduino environment status bar and the ARPIE has been updated.

You can check the firmware version installed on an ARPIE by holding the HOLD button while the device boots up (i.e. switch off/on or press reset). The version number is displayed as 4 binary coded decimal digits in a 99.99 format. The example below shows how version 1.03 is displayed

Please refer to the troubleshooting page for additional information.

ARPIE Hardware Info

Parts List

  • R1,R2, R3, R4, R18 – 220R carbon film resistor
  • R11, R12, R14, R15, R16, R17, R19, R20 – 1k carbon film resistor
  • R5, R6, R7, R8 – 1k5 carbon film resistor
  • R9, R10, R13 – 10k carbon film resistor
  • C5, C6 – 33pF ceramic capacitor 2.5mm pitch
  • C1, C2, C3, C4, C9 – 100nF ceramic capacitor 2.5mm pitch
  • C7, C8 – 4u7 electrolytic capacitor
  • D1, D2 – 1N4148 small signal diode
  • D3 – 1N4001 rectifier diode
  • TR1 – 2N3904 general purpose NPN switching transistor
  • IC1 – ATMEGA328P-PU microcontroller (with firmware)
  • IC2 – PIC12F1822 microcontroller (with firmware)
  • IC3, IC4 – 6N138 (or 6N139) high speed optocoupler
  • IC5 – 7805 +5V regulator TO-220
  • X1 – 16MHz low profile crystal
  • 2 off 74HC595D shift register SOIC16 (Pre-soldered to control surface PCB in standard kit)
  • 2 off 100nF ceramic cap 0805(Pre-soldered to control surface PCB in standard kit)
  • 3 off 8-pin DIL socket
  • 1 off 28-pin DIL socket
  • 1 off 2×10 0.1” DIL Female connector
  • 1 off 2×10 0.1” DIL Male connector long pins (~27mm)
  • 1 off 1×6 0.1” SIL Male header
  • 1 off 2.1mm DC socket PCB mount
  • 1 off Miniature slide switch
  • 3 off 5 PIN DIN socket PCB mount (check footprint)
  • 1 off PP3 battery holder PCB mount (check footprint)
  • 16 off 6x3mm tactile switch
  • 14 off 6x6mm tactlie switch
  • 16 off high brighness 3mm LED blue
  • 4 off standard 3mm LED Red
  • 3 off standard 3mm LED Green
  • 4 off Self adhesive rubber feet
  • 4 off M3x25mm Brass Hex Pillar
  • 8 off M3x6mm machine screw
  • 3 off M2.5x8mm machine screw
  • 3 off M2.5 nut
  • 1 off Control surface PCB
  • 1 off Main PCB

Header Pins Labels

  • KS2 – Data Switches Return*
  • SW1 – Hold button (Single switch, grounded when pushed, use pullup)
  • ENA – LED enable*
  • LD4 – HOLD LED (Single LEDS: input active HIGH, use series resistor)
  • LD3 – TX LED
  • LD2 – CLK LED
  • LD1 – RX LED
  • KS1 – Menu Switches Return*
  • DAT – Shift data*
  • SCK – Shift clock*
  • UN2 – Unassigned Digital Pin 11/PWM (PB3) use for your own hacks!
  • UN1 – Unassigned Digital Pin 14/Analog pin A0 (PC0) use for your own hacks!
  • GND – Ground
  • VCC – +5V

(*) KS1/KS2/ENA/DAT/SCK
Keys and LEDs are scanned by two 74HC595 shift registers. A single HIGH bit is clocked in (DAT/SCK) then clocked along all 16 shift register outputs in turn. For any output position ENA is pulled low to illuminate the associated LED and KS1 returns HIGH (pulldown needed) if associated menu button is down and KS2 returns HIGH (pulldown needed) if associated menu button is pressed. SCK is connected to both shift and store clock pins of both registers so a clock cycle is needed before the input pulse appears at the first output.

Schematics

  • Please check the github repo for EAGLE design files

Board Layouts

  • Please check the github repo for EAGLE design files

Source code

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