70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
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<!--
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---
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name: GPIO I2C pHAT
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class: board
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type: io
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formfactor: pHAT
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manufacturer: PlasmaDan
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description: 4 Extra I2C Buses for Raspberry Pi.
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github: https://github.com/plasmadancom/GPIO-I2C-pHAT
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buy: https://plasmadan.com/gpioi2c
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image: 'gpio-i2c-phat.png'
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pincount: 40
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eeprom: no
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power:
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ground:
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pin:
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'4':
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name: I2C3 SDA
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mode: i2c
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'15':
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name: I2C6 SDA
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mode: i2c
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'16':
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name: I2C6 SCL
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mode: i2c
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'29':
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name: I2C3 SCL
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mode: i2c
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'21':
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name: I2C4 SCL
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mode: i2c
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'24':
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name: I2C4 SDA
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mode: i2c
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'32':
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name: I2C5 SDA
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mode: i2c
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'33':
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name: I2C5 SCL
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mode: i2c
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-->
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# GPIO I2C pHAT
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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.
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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.
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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.
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## Features
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* Adds 4 additional I2C buses with breakout
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* User selectable I2C GPIO pin remapping
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* Slide switch allows fast bus switching
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* No-conflict solder jumpers
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* Stackable design
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* Immersion gold plated copper
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## Usage
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Add required dtoverlay parameter(s) to ```/boot/config.txt``` and reboot.
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| Switch Position | Hardware I2C (Pi 4) | Software I2C (Bit Bang) | GPIO |
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| :---: | :---: | :---: | :---: |
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| I2C3 | dtoverlay=i2c3 | dtoverlay=i2c-gpio,bus=3,i2c_gpio_sda=4,i2c_gpio_scl=5 | 4 5 |
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| I2C4 | dtoverlay=i2c4 | dtoverlay=i2c-gpio,bus=4,i2c_gpio_sda=8,i2c_gpio_scl=9 | 8 9 |
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| I2C5 | dtoverlay=i2c5 | dtoverlay=i2c-gpio,bus=5,i2c_gpio_sda=12,i2c_gpio_scl=13 | 12 13 |
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| I2C6 | dtoverlay=i2c6 | dtoverlay=i2c-gpio,bus=6,i2c_gpio_sda=22,i2c_gpio_scl=23 | 22 23 |
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Note: When using multiple software I2C buses, add the parameters from highest to lowest, i.e., 6, 5, 4, 3.
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