/*****************************************************************************
*
* Atmel Corporation
*
* File : main.c
* Compiler : IAR EWAAVR 2.28a/3.10c
* Revision : $Revision: 2516 $
* Date : $Date: 2007-09-27 10:41:15 +0200 (to, 27 sep 2007) $
* Updated by : $Author: mlarsson $
*
* Support mail : avr@atmel.com
*
* Supported devices : All devices with a TWI module the has a slave address mask
* register. The example is written for the ATmega48.
*
* AppNote : AVR311 - TWI Slave Implementation
*
* Description : Example of how to use the driver for TWI slave
* communication. This version utilises the address mask register
* to enable response on several TWI slave addresses.
*
****************************************************************************/
/*! \page MISRA
*
* General disabling of MISRA rules:
* * (MISRA C rule 1) compiler is configured to allow extensions
* * (MISRA C rule 111) bit fields shall only be defined to be of type unsigned int or signed int
* * (MISRA C rule 37) bitwise operations shall not be performed on signed integer types
* As it does not work well with 8bit architecture and/or IAR
* Other disabled MISRA rules
* * (MISRA C rule 109) use of union - overlapping storage shall not be used
* * (MISRA C rule 61) every non-empty case clause in a switch statement shall be terminated with a break statement
*/
#include <ioavr.h>
#include <inavr.h>
#include "TWI_Slave.h"
// Sample TWI transmission commands
#define TWI_CMD_MASTER_WRITE 0x10
#define TWI_CMD_MASTER_READ 0x20
// The AVR can be waken up by a TWI address match from all sleep modes,
// But it only wakes up from other TWI interrupts when in idle mode.
// If POWER_MANAGEMENT_ENABLED is defined the device will enter power-down
// mode when waiting for a new command and enter idle mode when waiting
// for TWI receives and transmits to finish.
#define POWER_MANAGEMENT_ENABLED
// When there has been an error, this function is run and takes care of it
unsigned char TWI_Act_On_Failure_In_Last_Transmission ( unsigned char TWIerrorMsg );
void main( void )
{
unsigned char messageBuf[TWI_BUFFER_SIZE];
unsigned char TWI_slaveAddress, TWI_slaveAddress2, TWI_slaveAddressMask;
// LED feedback port - connect port B to the STK500 LEDS
DDRB = 0xFF; // Set to ouput
PORTB = 0x55; // Startup pattern
// Own TWI slave address
TWI_slaveAddress = (0x10<<TWI_ADR_BITS);
TWI_slaveAddress2 = (0x11<<TWI_ADR_BITS); // Alternativ slave address to respond to.
TWI_slaveAddressMask = TWI_slaveAddress ^ TWI_slaveAddress2; // XOR the addresses to get the address mask.
// Initialise TWI module for slave operation. Include address and/or enable General Call.
TWI_Slave_Initialise( (unsigned char)(TWI_slaveAddress | (TRUE<<TWI_GEN_BIT)), TWI_slaveAddressMask);
__enable_interrupt();
// Start the TWI transceiver to enable reseption of the first command from the TWI Master.
TWI_Start_Transceiver();
// This example is made to work together with the AVR315 TWI Master application note. In adition to connecting the TWI
// pins, also connect PORTB to the LEDS. The code reads a message as a TWI slave and acts according to if it is a
// general call, or an address call. If it is an address call, then the first byte is considered a command byte and
// it then responds differently according to the commands.
// This loop runs forever. If the TWI is busy the execution will just continue doing other operations.
for(;;)
{
#ifdef POWER_MANAGEMENT_ENABLED
// Sleep while waiting for TWI transceiver to complete or waiting for new commands.
// If we have data in the buffer, we can't enter sleep because we have to take care
// of it first.
// If the transceiver is busy, we enter idle mode because it will wake up by all TWI
// interrupts.
// If the transceiver not is busy, we can enter power-down mode because next receive
// should be a TWI address match and it wakes the device up from all sleep modes.
if( ! TWI_statusReg.RxDataInBuf ) {
if(TWI_Transceiver_Busy()) {
MCUCR = (1<<SE)|(0<<SM2)|(0<<SM1)|(0<<SM0); // Enable sleep with idle mode
} else {
MCUCR = (1<<SE)|(0<<SM2)|(1<<SM1)|(0<<SM0); // Enable sleep with power-down mode
}
__sleep();
} else {
__no_operation(); // There is data in the buffer, code below takes care of it.
}
#else // No power management
// Here you can add your own code that should be run while waiting for the TWI to finish
__no_operation(); // Put own code here.
#endif
// Check if the TWI Transceiver has completed an operation.
if ( ! TWI_Transceiver_Busy() )
{
// Check if the last operation was successful
if ( TWI_statusReg.lastTransOK )
{
// Check if the last operation was a reception
if ( TWI_statusReg.RxDataInBuf )
{
TWI_Get_Data_From_Transceiver(messageBuf, 2);
// Check if the last operation was a reception as General Call
if ( TWI_statusReg.genAddressCall )
{
// Put data received out to PORTB as an example.
PORTB = messageBuf[0];
}
else // Ends up here if the last operation was a reception as Slave Address Match
{
// Example of how to interpret a command and respond.
// TWI_CMD_MASTER_WRITE stores the data to PORTB
if (messageBuf[0] == TWI_CMD_MASTER_WRITE)
{
PORTB = messageBuf[1];
}
// TWI_CMD_MASTER_READ prepares the data from PINB in the transceiver buffer for the TWI master to fetch.
if (messageBuf[0] == TWI_CMD_MASTER_READ)
{
messageBuf[0] = PINB;
TWI_Start_Transceiver_With_Data( messageBuf, 1 );
}
}
}
else // Ends up here if the last operation was a transmission
{
__no_operation(); // Put own code here.
}
// Check if the TWI Transceiver has already been started.
// If not then restart it to prepare it for new receptions.
if ( ! TWI_Transceiver_Busy() )
{
TWI_Start_Transceiver();
}
}
else // Ends up here if the last operation completed unsuccessfully
{
TWI_Act_On_Failure_In_Last_Transmission( TWI_Get_State_Info() );
}
}
}
}
unsigned char TWI_Act_On_Failure_In_Last_Transmission ( unsigned char TWIerrorMsg )
{
// A failure has occurred, use TWIerrorMsg to determine the nature of the failure
// and take appropriate actions.
// Se header file for a list of possible failures messages.
// This very simple example puts the error code on PORTB and restarts the transceiver with
// all the same data in the transmission buffers.
PORTB = TWIerrorMsg;
TWI_Start_Transceiver();
return TWIerrorMsg;
}
/*
// A simplified example.
// This will store data received on PORTB, and increment it before sending it back.
TWI_Start_Transceiver( );
for(;;)
{
if ( ! TWI_Transceiver_Busy() )
{
if ( TWI_statusReg.RxDataInBuf )
{
TWI_Get_Data_From_Transceiver(&temp, 1);
PORTB = temp;
}
temp = PORTB + 1;
TWI_Start_Transceiver_With_Data(&temp, 1);
}
__no_operation(); // Do something else while waiting
}
}
*/ |
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