4 Extra I2C Buses for Raspberry Pi


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EAN: 0616908588436 SKU: GPIO-I2C-PHAT Category:


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.

Uses the extra hardware I2C buses introduced on Raspberry Pi 4 (BCM2711) or software I2C (bit bang). Switching is controlled using a 4-position double-pole slide switch, which allows you to quickly switch between buses.

Multiple GPIO I2C boards can be stacked along with other HATs or pHATs, and it’s fully compatible with our HAT RACK mounting boards.

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.


  • Adds 4 additional I2C buses with breakout
  • Remaps I2C pins to work with add-on boards
  • Slide switch allows fast bus switching
  • No-conflict solder jumpers
  • Stackable design
  • Immersion gold plated copper
  • UL, CE, UKCA and RoHS (lead free) compliant
  • Compatible with our HAT RACK board

Device Compatibility

GPIO I2C pHAT is compatible with all 40-way Raspberry Pi models.

Device Model Compatibility
Raspberry Pi 1 Model A+/B/B+ ✔️
Raspberry Pi 2 Model B ✔️
Raspberry Pi 3 Model B/B+ ✔️
Raspberry Pi 4 ✔️
Raspberry Pi Zero ✔️



  • UL 796 certified manufacturer
  • RoHS compliant (lead free)
  • CE & UKCA marked


You can find this and our other Raspberry Pi projects on our GitHub page.


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.

Additional information

Weight 100 g


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