We have released a new firmware update! GPIO
Description of the GPIO header.
Overview
FREE-WILi includes a GPIO pin header for interacting with digital protocols. This GPIO header is flexible, allowing varying voltage levels and IO direction. The pin-out and connector are shown below.
IO Voltage Levels
The IO voltage levels are shared by all the GPIO. To set the voltage level you must inject a voltage on PIN4. This voltage can be set to 3.3v or 5.0v with a jumper. This would be a jumper between pins 2 and 4 for 5V. Or between 4 and 6 for 3.3V.
GPIO Pin Descriptions
The table below describes the pins. All GPIO except dedicated I2C pins can be used bidirectionally depending on the application. So the directions are the default.
| Pin | Description | Default Direction | Notes |
|---|---|---|---|
| 1 | SPI Chip Select Out | Output | |
| 2 | 5V Out | Output | 5V to power IO and external circuit |
| 3 | GPIO27 OUT | Output | RPi 2040 GPIO27 |
| 4 | V PINS IN | Input | Input to set the IO voltage 1.1 to 5.5V |
| 5 | UART1 Rx IN | Input | RPi 2040 UART 1 Receive (GPIO9) |
| 6 | 3.3V Out | Output | 3.3 V to Power IO and external circuit |
| 7 | UART1 CTS IN | Input | RPi 2040 UART 1 Clear To Send (GPIO10) |
| 8 | I2C0 SCL | In/Out | RPi 2040 I2C 0 Clock (GPIO17) |
| 9 | UART1 TX OUT | Output | RPi 2040 UART1 Transmit (GPIO8) |
| 10 | I2C0 SDA | In/Out | RPi I2C 0 Data (GPIO16) |
| 11 | UART1 RTS OUT | Output | RPi 2040 UART 1 Request To Send (GPIO11) |
| 12 | SPI1 RX IN | Input | RPi 2040 SPI 1 Receive (GPIO12) |
| 13 | SPI1 TX OUT | Output | RPi 2050 SPI 1 Transmit (GPIO15) |
| 14 | GPIO 26 IN | Input | RPi 2040 GPIO26 |
| 15 | SPI1 SCLK OUT | Output | RPi 2040 SPI 1 Clock (GPIO14) |
| 16 | SWCLK IN | Input | RPi 2040 debugger clock input for external SWD debugger. |
| 17 | GPIO25 OUT | Output | RPi 2040 GPIO25. GPIO25 also connects to board status LED (same as RPi Pico) |
| 18 | SWDIO | In/Out | RPi 2040 debugger IO for external SWD debugger. |
| 19 | GND | ||
| 20 | GND |
I2C Interface
The I2C interface is connected to the RPi I2C0 peripheral. The I2C Interface uses the chip PCA9517 for buffering. Please see the data sheet below for details.
PCA9517-3139014.pdf
IO Pins Interface
All the GPIO that is not I2C uses the sn74lxc1t45 for buffering.