pico-arduino
Overview
So far this has been just a Toy Project, but with the addition of SPI we can now take on more complex Arduino projects.
In order to verfiy and test the implementation of the Arduino SPI interface. I added the SdFat library from Bill Greiman (https://github.com/greiman/SdFat) and just used the SdInfo example. SdFat Version 2 supports FAT16/FAT32 and exFAT SD cards.
You can find more examples in the SdFat/exampes directory.
The Arduino HardwareSPI interface is using the Pico API with the following default pins
- spi0: pinRx = 16; pinTx = 19; pinCS = 17; pinSCK = 18;
- spi1: pinRx = 12; pinTx = 11; pinCS = 13; pinSCK = 10;
On the master MISO = pinRx and MOSI = pinTx
Connections for SD Module
| SD | Pico |
|---|---|
| CS | SPI-CS0 (GPIO 17) |
| SCK | SPI-SCK (GPIO 18) |
| MOSI | SPI-TX (GPIO 19) |
| MISO | SPI-RX (GPIO 16) |
| VCC | VBUS (5V) |
| GND | GND |
Configuration
When I first tested the functionality, I wondered why the functionality did not work properly.
- It turned out that USE_SIMPLE_LITTLE_ENDIAN must not be set to 1. This is changed in the SdFatConfig.h
- I also needed to lower the max speed from 16MHz to 12MHz.