Assembly Manual

The Audio Shield Rev D2 stacks directly on top of the Teensy 4.1 via two rows of female headers. You need 2 × 14-pin female headers (cut from a 40-pin strip).

1. Cut headers: Count 14 pins on the strip and cut with flush cutters. You need two 14-pin pieces. Cut on the 15th socket to avoid cracking pin 14.
2. Insert headers into Teensy: Push the two 14-pin female headers onto the Teensy's outer male pin rows (the two long rows of pins along each edge). The headers sit on top of the Teensy, sockets facing up.
3. Stack the Audio Shield on top: Place the Audio Shield board onto the headers so the shield's through-holes line up with all 28 header pins. The Audio Shield's 3.5mm jack should face the same end as the Teensy's USB port. The Teensy is your alignment jig — stacking before soldering guarantees all pins are straight and spaced correctly.
4. Solder from the TOP of the Audio Shield: Flip the stack so the Audio Shield PCB is on the bottom. The header pins now poke through the Audio Shield's top surface. Solder each pin where it comes through the Audio Shield PCB. Do NOT solder anything to the Teensy itself.
5. Technique: Heat the pad and pin together for 2 seconds, feed solder until it flows around the pin and wets the pad. Move to the next pin. Do corners first to lock alignment, then fill in the rest.
6. Separate: After all 28 joints cool, gently pull the Audio Shield off the Teensy. Inspect every joint — look for bridges between adjacent pins and cold joints (dull/blobby). Reflow any bad joints.

1. Format as FAT32 (not exFAT).
2. Copy PJRC test WAV files to root.
3. Insert into Teensy built-in slot (not Audio Shield slot).

1. Teensy into breadboard (spans center gap).
2. Audio Shield on top via headers.
3. Headphones into Audio Shield 3.5mm jack.
4. USB to computer.

#define SDCARD_CS_PIN    BUILTIN_SDCARD
// DO NOT use pins 10/7/14 for SD
// Those are Audio Shield SD (unused)

Open WavFilePlayer example. Set CS pin as above. Upload. Serial Monitor 9600 baud.

Cut 8 pieces of copper tape (~20×20mm). Stick on cardboard in 2×4 grid, 5mm spacing. Solder wire to each. Connect to C1–C8.

Wire1.begin();
Adafruit_CAP1188 cap = Adafruit_CAP1188();
cap.begin(0x29, &Wire1);  // I2C1 at 0x29

Serial Monitor: touch each pad → see event. Then integrate: pad N triggers sample N via AudioPlaySdWav.

I2C scan on Wire should show: 0x0A (SGTL5000) + 0x3C (SSD1306).

Data → pin 6 via 470Ω series resistor. VCC → 5V. GND → GND.

Each pot: Left → GND, Right → 3.3V, Wiper → ADS1115 A0–A3. Pot 5 wiper → Teensy pin 14 (A0).

Add 100nF ceramic cap from each wiper to GND, close to the ADC input.

Adafruit_ADS1115 ads;
ads.begin(0x48, &Wire);
// ads.readADC_SingleEnded(0) ... sweep 0 to ~26000

If jumpy: check 100nF caps, keep wiper wires away from SPI lines.

Watch the notch — pin 1 at the notch end. Both on I2C1 (16/17). #1 at 0x20 (A0/A1/A2 = GND). #2 at 0x21 (A0 = 3.3V). RESET pins → 3.3V. 100nF cap on each VDD–VSS.

Each EC11: C (common) → GND, A + B → MCP GPIO, SW → MCP GPIO. Enable MCP internal pull-ups in firmware. 5 encoders on MCP#1, 2 on MCP#2.

Common → GND. Up/Down/Left/Right/Select → MCP#2 GPIOs. Internal pull-ups.

Adafruit_GPS GPS(&Wire);
GPS.begin(0x10);
GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);

Flash WiFi test via its own USB port before wiring to Teensy. Verify it connects to your network.

// Teensy:
Serial1.begin(115200);
if (Serial1.available()) {
  String msg = Serial1.readStringUntil('\n');
  Serial.print("From ESP32: ");
  Serial.println(msg);
}