git.zerfleddert.de Git - rsbs2/blob - bmc/i2c.c

   1 #include <util/twi.h>
   2 #include <avr/interrupt.h>
   3 #include <stdio.h>
   4 #include "i2c.h"
   5 #include "bmc.h"
   6
   7 #define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
   8 #define TWCR_NACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
   9 #define TWCR_RESET TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(0<<TWWC);
  10
  11 static volatile unsigned char databuf[12];
  12 static volatile uint8_t pos = 0x00;
  13
  14 void i2c_init()
  15 {
  16         TWAR = BMC_ADDR & 0xfe;
  17         TWDR = 0x00;
  18         TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
  19         TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE));
  20         printf("Status: 0x%02x\n", TW_STATUS);
  21         PORTC = 0x03;
  22 }
  23
  24 ISR (TWI_vect, ISR_BLOCK)
  25 {
  26         switch (TW_STATUS) {
  27                 case TW_SR_SLA_ACK:
  28 #ifdef DEBUG
  29                         printf("I2C: Slave 0x%02x adressed\n", TWDR);
  30 #endif
  31                         pos = 0x00;
  32                         TWCR_ACK;
  33                         break;
  34
  35                 case TW_SR_DATA_ACK:
  36 #ifdef DEBUG
  37                         printf("I2C: Data received: 0x%02x\n", TWDR);
  38 #endif
  39                         databuf[pos] = TWDR;
  40                         pos++;
  41                         TWCR_ACK;
  42                         break;
  43
  44                 case TW_SR_STOP:
  45 #ifdef DEBUG
  46                         printf("I2C: STOP received\n");
  47 #endif
  48                         decode_bmc_cmd((unsigned char*)databuf, pos);
  49                         pos = 0x00;
  50                         TWCR_RESET;
  51                         break;
  52
  53                 case TW_ST_SLA_ACK:
  54                 case TW_ST_DATA_ACK:
  55                         printf("I2C: Data requested\n");
  56                         TWDR = 0x00;
  57                         TWCR_ACK;
  58                         break;
  59
  60                 default:
  61                         printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
  62                         TWCR_RESET;
  63                         break;
  64         }
  65 }