i2c_init

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Description

Initialize the I2C module of the controller. Currently, only a fixed setting is used, namely:

• I2C standard mode with 7b addresses
• fixed speed of 100kBaud
• no clock stretching
• broadcast receive disabled

Inclusion

• defined in i2c.h
• not loaded by main_general.h
• for custom I2C interrupts set set #define USE_I2C_ISR in config.h. The corresponding interrupt function name is I2C_ISR

Syntax

i2c_init()

Parameters

• input:

  • none

• output:

  • none

Returns

• Nothing

Example Code

The below function controls a digital potentiometer AD5280. Specifically it sets the resistance between terminal A and washer to R=Rmax/255*res

#include "i2c.h"

...
void setAD5280(uint8_t addr, uint8_t res) {
  uint8_t  buf[2] = {0x00, res};
  i2c_start();
  i2c_send(addr,2,buf);
  i2c_stop();
}

setup() {
  ...
  i2c_init();
  ...
}

Relevant Tutorial

• General_Examples/I2C_write

Notes and Warnings

To avoid damage

• do not expose I/Os to voltages outside [-0.3V; Vdd+0.3V], else limit injection currents to the specificied limits
• for OUTPUT pins assert that sink and source currents are below the specificied limits
• do not directly connect two OUTPUT pins. If e.g. half-duplex is required, use a pull-up and OUTPUT_OPENDRAIN, instead

See also

• i2c_init()
• i2c_start()
• i2c_stop()
• i2c_send()
• i2c_request()