Full Build Instructions for pi-Stomp Core v2.0.4 with AudioInjector card

For pi-Stomp Original 1.0.1 build instructions, go here

For pi-Stomp Original 1.0.2 build instructions, go here

For pi-Stomp Core 2.0.3 build instructions, go here

For pi-Stomp Core 2.0.4 with IQAudio Codec Zero card, go here

Bill of Materials for board version 2.0.4

Back to the Main pi-Stomp Core page

Do not attempt to build this if you are not already comfortable soldering printed circuit boards. This is a rather advanced project, not intended for beginners

Tree Fall Sound cannot be held responsible for any damages or injury which may result during assembly or usage

Tree Fall Sound cannot be held responsible if your build does not function as expected

All parts should be inserted from the side of the circuit board on which they are labeled (silk screened), then soldered from the opposite side. Installing on the wrong side, will cause problems, in most cases, Big problems. It's very difficult to unsolder a multi-pinned part like a header or jack without harming the board or part. If it becomes necessary and you find it difficult to unsolder a part, it's often best to just sacrifice it by cutting its leads then clearing the holes for a new part.

If you choose to go FULL DIY and ignore the following instructions, please at least view the photo depicting each step (click on any photo to enlarge it) and read any instructions with bold text or a warning icon: . These are critical steps, or steps with quirks which might cause issues if not performed as suggested.

Some steps have options to allow for system customization. Those are tagged with a question mark icon: It might be a good idea to consult the Customization guide and consider your customizations prior to building.

We've tried to identify and iron out potential build issues, but you might encounter your own. Identifying a problem and figuring out a way to fix it is part of the fun of DIY. That said, if the instructions aren't clear, you run into problems or just have questions, post to the build forum or email: support@treefallsound.com

It's advised to have the BoM pi-Stomp Core Bill of Materials handy (either open in a browser window or printed). The order of these steps roughly corresponds to the order of the BoM and was chosen to facilitate assembly. Could be helpful to check off each part in the BoM, once it's installed.

Here is a good guide for soldering. In addition to that I have a few extra suggestions:
- Keep your tip clean using a wire sponge or damp sponge or both. Oxidation (black stuff) prevents heat transfer and can result in cold joints. I suggest wiping it at least every 4 or 5 joints and definitely once when you're finished with a round.
- It's tempting to just feed the solder into the iron. The flow of the solder follows the heat, so heat the pad and component lead for a second or two, THEN feed the solder into the junction. If the solder doesn't melt, pull the iron away and melt a dab of solder, then go back to heating the junction.
- Don't apply too much solder (see guide below). Almost as soon as it flows, I stop feeding. Small diameter solder is recommended (0.8mm / 0.031“).
- Keep the iron on the joint for a second or so after the solder flows.
- Don't keep the iron on the joint any longer than necessary. Excessive heat can damage components.

Good idea to inspect your soldering under magnification to assure you didn't bridge short any pads. The headers with 0.1” spacing are especially prone to this. You can check for shorts using a continuity meter. Here's an excellent guide to identifying other solder joint issues: Adafruit soldering guide - common problems

Take your time! A rushed job during assembly could reward you with many hours of debugging later, or worse, a high tech doorstop. The possible bright side there, is that it's a fairly modular design and the most expensive components (Pi, LCD, audio board, IC's, etc.) are easily detachable. So if you mess up the board, a lot of the parts can be salvaged. If you're stuck with a build mistake, post to the build forum, or contact support@treefallsound.com for suggestions.

All Set? LET'S BUILD!

Before you commence building, it's highly advisable to consider how you plan to mount your pi-Stomp. Specifically, you should decide whether you plan to mount top-mount the LCD above the enclosure face, or under-mount it. Your choice will affect Step #9 whether to install the LCD header or not.

Check out examples of top-mounting and under-mounting methods here

Under-mounting looks far more professional and better protects the LCD. But it requires being able to cut a rather sizable rectangular cutout where top-mount just requires a simple slot. Another disadvantage of under-mounting is that you cannot socket the LCD, it must be soldered to the pi-Stomp board because no socket exists short enough to allow the LCD face to sit below where the volume pot and encoder end up. One could avoid mounting the pot and encoder and flywire them to the board, or use a 9-pin ribbon cable to place the LCD away from the pi-Stomp board, but those are specialized builds not covered here.

Below are the parts needed for assembling the pi-Stomp Core PCB. If you seem to be missing some, make sure you look in the Rasberry Pi box.

To save you from the often frustrating soldering of surface mount components, we've presoldered the voltage regulator for you. You're welcome!

Bend the legs and insert all resistors R1, R2, R3 & R4 (2Meg) from the silkscreened side.
Splay the leads slightly to keep them positioned
Repeat for R5 (33 ohm - orange/orange/black/gold)
R6, R7 & R8 are only required if you're going to be using the extra 3 GPIO pins (for LED's, etc.) and require a voltage drop / current limit. Calculate the value as appropriate for your load or add a simple wire jumper if you're using the GPIO as an input.

Solder from the lead side and trim

Insert C1 and C2 (red 0.1uF), splay leads (non-polarized)
Insert C3 and C4 (smaller yellow 0.1uF), splay leads (non-polarized)
Using needle nose pliers, straighten the pre-bent leads for the 10uF oscon capacitor C6 and insert. Make sure the negative lead, marked with the blue paint, goes thru the hole marked with “-” (also has a square solder pad)
C5 is optional. 10uF or greater if ripple is a problem.

Solder all pads, clip leads

Trim the Fuse (looks like a ceramic capacitor) leads just above the bend:

Insert (orientation doesn't matter). Solder, Trim.

Insert both transistors (Q1 & Q2) with the flattened side matching the silkscreen. Splay the leads, solder, trim. Too much heat can damage a transistor, don't linger with the iron. If you can't solder in less than 3 seconds or so, attach a heat sink tweezer to the transistor side of the lead.

Pay close attention to which side the header should be inserted - the side with the silkscreened name. Unsoldering a misplaced header is not fun.

It's important for headers to sit tight and perpendicular to the board (except where noted otherwise). I use tape to keep it in place until a pin (or two) is soldered, then adjust as necessary before soldering the remaining pins

This header is optional but recommended if you might need access to extra GPIO pins for Outputs (LED's, etc.) or direct (not ADC or debounced) inputs.

This header can be installed on either side of the board. If you do mount it on top (side with the volume and encoder), angle the pins slightly upward (maybe 10 to 15 degrees) so that jumpers can be attached and clear the IC which will be installed South of it later.

The bottom side (side with header silkscreen and the red capacitors), is generally recommended and shown in this build. Angling the pins slightly upward just a few degrees can make it easier to attach jumpers.

Secure with tape (or other means).
solder

Secure at both ends. Perpendicular as possible to the board..
Solder. The 40 pins are rather close and solder bridges between pads would be bad, so take your time and don't over-solder

These are the headers for the output and input jumpers. When complete they should look like this:

Note how the black plastic ends up perpendicular to the board not flush to it.

Use tape to secure each while soldering. It can help with positioning if you attach a jumper as it will be when eventually connected.

HOut header:

HIn header:

This provides the interface for attaching, switches, MIDI and analog inputs.

To allow best access to these pins when the whole board sandwich is assembled, make sure the pins are not angled inward but either straight up or maybe just a few degrees outward (away from the board edge)

The sockets have a notch to indicate pin #1. Orient that to match the silkscreen notch.

Insert S1 (14-pin). Secure (with tape, etc.) and solder

S2 (the ADC socket) is recommended for most builds unless you plan to replace the ADC with your own hardware connected via SPI (see the Customization guide)

Insert S2 (16-pin). Secure and solder

Insert S3 (8-pin). Secure and solder

Insert Rly. Note the line across one end of the relay. This must end up at the end with the “Rly” board label as shown
Secure with tape and solder. Note the pads are very small. Be sparing with the solder.

Make sure these are inserted from the correct board side. Unsoldering them is a bitch.

Insert JPwr

To increase mechanical sturdiness, before soldering, bend over terminals with a blunt, plastic utensil (eg. butt end of a Sharpie).

Solder. Large pads so make sure you use plenty of solder.

Insert JIn and JOut

Secure solidly against the board
Solder. Small pads, be sparing with solder.

Vol pot P1 has a “keying” tab (unless it's already been removed) which, although is less than 1mm tall, will prevent the pot from sitting flush to inside face of the enclosure when mounted. It's important for it to sit flush. So you can either decide to drill a small divot on the inside of the enclosure (doesn't need to completely pierce the face), break it off with needle nose pliers, or file the tab down. If you do file it, it's good to cover the shaft and threaded shank in tape to protect them from damage or metal dust.

Insert Vol pot P1
To increase mechanical stability, I recommend bending over the side tabs with a blunt plastic tool like the butt end of a sharpie

Solder 6 pins plus the side tabs

The last part is often the trickiest. The encoder Enc has very short pins, but for it to sit tight against the enclosure face, it (plus the included nylon washer) needs to sit at roughly the same level as the Vol pot. It should rest on its side tabs at the appropriate level, however, it can rock and end up not perpendicular to the board. So…

Secure with tape on each side to make it perpendicular

Solder just one of the 5 pins. Because of the short pins, you may need to solder from the top (encoder side) of the board.
Make sure it's still as perpendicular as possible. If not, adjust. Reheat the solder if necessary. Once it's good, solder the remaining pins.
Solder the side tabs to the pads on the top of the board (for mechanical stability)

Congratulations, the board is complete!

The pins of the IC's usually need to be bent inward just a millimeter or two before inserting. Lightly squeeze all pins between thumb and first finger.

All IC's are polarized. Make sure the notch/dimple (indicating pin #1) ends up on the same end as the silkscreen (and sockets if you installed them right). Worse case, match the photos below.

Insert U1 (14-pin debounce chip: LS19-A)
Insert U2 (16-pin ADC chip: MCP3008)

Insert U3 (8-pin opamp: MCP6292-E/P)

Two jumpers attach the Audio Board to the pi-Stomp PCB.

First cut a 3-wire jumper in half (color doesn't matter)

Separate the individual wires (maybe 1 to 2 cm)
Strip about 3mm from each wire and twist the copper strands
Tin each end (heat and add just a spot of solder)
Can be tricky holding the board, wire, iron and solder. A “third hand” helps, Also a pair of pliers with a rubber-band can hold the board. Worst case, ask a friend.

Insert the 3 wire ends into the top (component) side of the board labeled “Input” and solder.

Cut the other half to around 7cm (2.75“).

Split off two of the 3 wires
Strip and tin the two wires as before
Insert the 2 wire ends into the top side of the board labeled “Output” but just the two outside pads, not “Gnd”

Hold in place and Solder

The Pimoroni Hat Hacker should have included 6 10mm metal hex spacers and 12 metal screws. We'll use those along with the nylon spacers for assembling. We'll be using all the screws so try not to loose them.

Attach two 10mm metal spacers using two screws to the Audio Board

They should attach on the edge opposite of the 40-pin header

Attach two 12mm nylon spacers using two screws to the Hat Hacker

They should attach on either side of the edge 40-pin header (male pin side)

Attach two 8mm nylon spacers plus 1mm nylon washers to the Pi using two screws.

They should attach on the edge opposite of the 40-pin header. The stack results in a 9mm spacer.

Stack the Hat Hacker onto the Raspberry Pi. Seat completely and attach with two screws.

Stack the Audio Board onto the center 40-pin header of the Hat Hacker. Attach with two screws from below. Note that since the audio board has a short header, there will be a slight gap (~2mm) between male and female headers.

Depending on how you plan to enclose the pi-Stomp, you need to decide whether to Top-mount the LCD and install a header (HLCD) for it, OR Under-mount the LCD and solder it directly to the board. Top-mount with a header may be the most versatile, but Under-mount will generally be the most professional looking. See Enclosure Considerations for examples.

It's not quite as aesthetically pleasing, but it makes machining of the enclosure easier (only a narrow slot for the pins is required) and it allows for unplugging/swapping the LCD.

The provided HLCD 1×9 female header should result in the display sitting on top of the enclosure top panel surface if your enclosure face is 3mm or less. You should measure the ending height of the LCD with the header to assure it will extend the right amount thru the slot in your enclosure. If it needs to extend further, you could raise the header slightly from flush before soldering.

As with the other headers installed in step #4, secure in place with tape

Then solder the 9 pins from the opposite side.

Now stack the pi-Stomp board onto the main Hat Hacker 40-pin header. Seat completely and attach with two screws.

Connect the 3-pin Audio Board Input cable to the pi-Stomp board. Each pin is labeled on each board with “L” for left, “G” for ground, and “R” for Right. Make sure you connect like pins.

Similarly connect the 2-pin Output cable. It only has “L” and “R”, no ground.

Plug the LCD into the pi-Stomp board 9-pin header.

Quite the sandwich, eh? Your pi-Stomp Core is complete!

If you want the LCD to be mounted underneath the top panel then you won't be able to use a plug-able header because that would place the top surface of the LCD above the pot and encoder. Your enclosure would need a rectangular cutout which is fairly simple with CNC or milling machine. It's not as easy without those tools, but possible with some patience by drilling lots of holes and filing to your rectangular outline. For this method, you'll be soldering the LCD directly to the board.

Three spacers HW21 - HW23 (6mm tall) can be glued between the pi-Stomp board and the LCD to keep it parallel and at the right height - just below the enclosure face when the volume pot and encoder are mounted.

You'll want to place the spacers so they're flush against the boards, between solder pads. Requires a bit of Test fitting the LCD.

If the final height of the pot and encoder ends up higher than the spacer, you might need to file them down slightly.

A light layer of hot glue affixes the spacers and breaks fairly easy if you get it wrong.

Because the LCD, once soldered, will obscure the audio In header, you'll need to connect the 3 wire jumper from the Audio board, before attaching the LCD, Each pin is labeled on each board with “L” for left, “G” for ground, and “R” for Right. Make sure you connect like pins.