Pinout
Every pin on the Daisy’s 40-pin header is spoken for.
The 40-pin header
Section titled “The 40-pin header”| Seed pin | STM32 | Rev B use |
|---|---|---|
| 1 | PB12 | SPI expansion chip-select, 10 kΩ pull-up |
| 2 | PC11 | Satellite chain RX (USART3) |
| 3 | PC10 | Satellite chain TX (USART3) |
| 4 | PC9 | Second codec reset |
| 5–7 | PC8, PD2, PC12 | SD card, 1-bit SDMMC |
| 8 | PG10 | I/O connector D1 — digital only |
| 9–11 | PG11, PB4, PB5 | SPI1 to the expansion header |
| 12–13 | PB8, PB9 | I²C1, four taps, pull-ups on the motherboard |
| 14–15 | PB6, PB7 | MIDI (USART1) |
| 16–19 | — | Onboard codec in and out (SAI1) |
| 22–28 | PC0, PA3, PB1, PA7, PA6, PC1, PC4 | I/O connectors A1–A7 — digital or analog |
| 29–30 | PA5, PA4 | I/O connectors CV2, CV1 — DAC out or analog in |
| 31–35 | PA1, PA0, PD11, PG9, PA2 | Second codec (SAI2): MCLK, data in, data out, LRCK, SCLK |
| 36–37 | PB14, PB15 | USB data, out to the power board |
| 39–40 | — | VIN, GND |
Two notes worth having before you plan around it:
- PB1 (pin 24) and PC1 (pin 27) share external-interrupt line 1. Do not plan both as interrupt-driven clock or gate inputs.
- Pin 8 is the only I/O connector that cannot read analog. The other seven, plus the two DAC pins, reach the Seed’s own converter.
General-purpose I/O connectors
Section titled “General-purpose I/O connectors”Ten connectors, all the same 3-pin JST SH.
| Pin | Signal |
|---|---|
| 1 | GND |
| 2 | Signal, through 1 kΩ at the connector |
| 3 | +3V3_A |
The 1 kΩ series resistor protects the pins — two of them are not 5 V tolerant — and does not affect internal pull-ups, pot readings, or a DAC driving an op-amp.
The supply is +3V3_A, the quiet LDO rail. Ten 10 kΩ pots draw about 3 mA of its
300 mA, and a shorted panel cable hits the LDO’s current limit and takes down
only these connectors.
CV outputs reach 0–3.3 V, so useful CV ranges need an op-amp stage. That belongs on the jack board, powered from the audio ribbon.
SPI expansion header
Section titled “SPI expansion header”Seven pins, for the optional ADC expander or a display.
| Pin | Signal |
|---|---|
| 1 | +3V3_D |
| 2 | GND |
| 3 | SPI_MOSI, 33 Ω at the Seed |
| 4 | SPI_MISO |
| 5 | SPI_SCK, 33 Ω at the Seed |
| 6 | SPI_EXT_CS, 10 kΩ pull-up |
| 7 | +3V3_A, for the expander’s ratiometric pots |
An SPI display works here too, but most need a data/command pin and often a reset pin beyond SPI — those come from the general-purpose I/O connectors. A second SPI device needs a second chip-select, which this header does not have.
Full reasoning, including what still needs bench work:
hardware/rodeo-motherboard/docs/rev-b.md.