I2C

This page will summarize the informations to use the I2C bus on our boards.

Tested I2C chips

• RTC
• DAC (MAX5821)
• CH7024

APF9328 I2C bus logic level adaptation (if necessary)

On the APF9328 the I2C bus has a 3,3V logic level so if you want to use 5V I2C devices you have to add a level converter, for example a PCA9306 from NXP (ex Philips):

• Connect pin 1 to the local GND
• Connect pin 2 to the local 3.3V
• Connect pin 3 to the SCL output of the APF
• Connect pin 4 to the SDA input/ouput of the APF
• Connect pin 7 and 8 together and the add a 200K resistor in parallel to a 100nF capacitor to GND
• Connect a pullup of 1.7K to the 5V SCL line (pin 6)
• Connect a pullup of 1.7K to the 5V SDA line (pin 5)

For more details, take a look at the PCA9306 datasheet. This chip is the one that will be used on the DevFull board.

Links

• Vincent Himpe I2C FAQ mirror