I²C example

Introduction

This is a simple example of how to implement an I²C master interface using two GPIO pins. The example consists of two separate applications, the first (master) is a full blown C application that sends and receives data. The second is a standalone assembler application that acts as the slave.

Master

The master application uses the BSP to open and initialise the GPIO port, but then uses direct register access to actually do the bit toggling. It repeated sends and then receives 16 bytes across the bus. It uses GPIO A, bit 0 for the data and GPIO A, bit 2 for the clock.

Slave

The slave application does not use the BSP or RTOS, instead is coded in assembler to ensure that all bit transitions are correctly detected. The slave can receive I²C messages of up to 1024 bytes. Once the message is received, it dumps the contents of the message to UART 0. It uses GPIO A, bit 0 for the data and GPIO A, but 1 for the clock.

Building the example

Change directory to the I²C example

    cd %LF_HOME%\examples\i2c

Rebuild the application
lfmake clean all

Running the example

Connect GPIO A bit 0 on the slave board to GPIO A bit 0 on the master board.
Connect GPIO A bit 1 on the slave board to GPIO A bit 2 on the master board.
Connect a ground cable between the two boards.

To run the slave on the board

lfdownload -a <slave board address>
i2c_slave.bin

To run the master on the board

lfdownload -a <master board address>
i2c_master.bin

Features

This example demonstrates the following SDK features.