I2C/TWI with AVR Introduction

by Conrad Gomes on

In this post we’ll take a look at implementing an I2C/TWI library which can be used with Atmel’s AVR micro-controller.

The code has been uploaded to GitHub at https://github.com/zeuzoix/sardine and will be referenced here. The TWI library consists of the following files:

  1. twi.h

  2. twi.c

  3. twi_states.h

  4. twi_states.c

  5. twi_debug.h

There are two API which the application can use to interface with the I2C/TWI interface. The prototypes are in twi.h

   uint32_t ui_data_sz;

}TWI_SEND_RECV_BUFFER_PARAMS_X;


TWI_RET_E twi_init(TWI_INIT_PARAMS_X *px_init_params);
TWI_RET_E twi_send_recv_buffer(TWI_SEND_RECV_BUFFER_PARAMS_X *px_send_buffer_params,
                               TWI_MODE_E e_mode);

#endif

The first API twi_init is used to initialize the TWI interface in master mode by assigning a set of register values to the TWI registers in the AVR Atmel micro-controller.

The second API twi_send_recv_buffer is used in both transmit and receive mode to send and receive data over the TWI SDA data line.

We’ll take a look at the registers used in the programming of the TWI interface in the next section i.e.

I2C/TWI with AVR Register Descriptions.