52 lines
1.3 KiB
Markdown
52 lines
1.3 KiB
Markdown
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<!--
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---
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name: I2C
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class: interface
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type: pinout
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description: Raspberry Pi I2C pins
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url: http://www.raspberry-projects.com/pi/programming-in-python/i2c-programming-in-python/using-the-i2c-interface-2
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pin:
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'3':
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name: Data
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direction: both
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active: high
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'5':
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name: Clock
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direction: both
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active: high
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'27':
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name: EEPROM Data
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direction: both
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active: high
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'28':
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name: EEPROM Clock
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direction: both
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active: high
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-->
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# I2C - Inter Integrated Circuit
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GPIO 2 and GPIO 3 - the Raspberry Pi's I2C1 pins - allow for two-wire communication with a variety of external sensors and devices.
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The I2C pins include a fixed 1.8 kΩ pull-up resistor to 3.3v. They are not suitable for use as general purpose IO where a pull-up might interfere.
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I2C is a multi-drop bus, multiple devices can be connected to these same two pins. Each device has its own unique I2C address.
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You can verify the address of connected I2C peripherals with a simple one-liner:
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```bash
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sudo apt-get install i2c-tools
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sudo i2cdetect -y 1
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```
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You can then access I2C from Python using the smbus library:
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```python
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import smbus
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DEVICE_BUS = 1
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DEVICE_ADDR = 0x15
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bus = smbus.SMBus(DEVICE_BUS)
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bus.write_byte_data(DEVICE_ADDR, 0x00, 0x01)
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```
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GPIO 0 and GPIO 1 - I2C0 - can be used as an alternate I2C bus, but are typically used by the system to read the HAT EEPROM.
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