2.2 KiB
GPIO I2C pHAT
The GPIO I2C pHAT is an I2C switch for Raspberry Pi which remaps the I2C bus (pins 3 & 5) to 1 of 4 additional buses, allowing any I2C based add-on board to use an alternative I2C bus, without the need for multiplexers or expanders.
Makes use of the extra hardware I2C buses introduced on Raspberry Pi 4 (BCM2711) or software I2C (bit bang). Multiple GPIO I2C boards can be stacked along with other HATs or pHATs. Switching is controlled using a 4-position double-pole slide switch, which allows you to quickly switch between buses.
Includes a breakout header for the 4 extra I2C buses. These are always connected to the associated GPIO pins so can be used regardless of the switch position. Note: external pull-up resistors to 3.3V required.
Features
- Adds 4 additional I2C buses with breakout
- User selectable I2C GPIO pin remapping
- Slide switch allows fast bus switching
- No-conflict solder jumpers
- Stackable design
- Immersion gold plated copper
Usage
Add required dtoverlay parameter(s) to /boot/config.txt and reboot.
| Switch Position | Hardware I2C (Pi 4) | Software I2C (Bit Bang) | GPIO |
|---|---|---|---|
| I2C3 | dtoverlay=i2c3 | dtoverlay=i2c-gpio,bus=3,i2c_gpio_sda=4,i2c_gpio_scl=5 | 4 5 |
| I2C4 | dtoverlay=i2c4 | dtoverlay=i2c-gpio,bus=4,i2c_gpio_sda=8,i2c_gpio_scl=9 | 8 9 |
| I2C5 | dtoverlay=i2c5 | dtoverlay=i2c-gpio,bus=5,i2c_gpio_sda=12,i2c_gpio_scl=13 | 12 13 |
| I2C6 | dtoverlay=i2c6 | dtoverlay=i2c-gpio,bus=6,i2c_gpio_sda=22,i2c_gpio_scl=23 | 22 23 |
Note: When using multiple software I2C buses, add the parameters from highest to lowest, i.e., 6, 5, 4, 3.