#define TWCR_NACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
#define TWCR_RESET TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(0<<TWWC);
-volatile unsigned char i2c_databuf[12];
+volatile unsigned char i2c_databuf[24];
volatile uint8_t i2c_len = 0x00;
static volatile uint8_t i2c_pos = 0x00;
volatile uint8_t i2c_done = 0x00;
+#define I2C_FREQ 20000UL
+
void i2c_init()
{
- TWBR = 0xff;
+ /* SCLf = F_CPU / (16 + 2 * TWBR * 4^TWPS)
+ * TWPS is 0 =>
+ * TWBR = (F_CPU/(2 * SCL)) - 8
+ */
+ TWBR = (F_CPU/(2*I2C_FREQ))-8;
TWAR = BMC_ADDR & 0xfe;
TWDR = 0x00;
TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE));
+#ifdef __AVR_ATmega16__
PORTC = 0x03;
+#else
+#error "Don't know how to set pullups for this chip, please add support"
+#endif
}
void i2c_send(unsigned char *buf, int len)
TWCR = ((1<<TWINT) | (1<<TWSTA) | (1<<TWEN)); /* Send start */
while(!(TWCR & (1<<TWINT))) {}
- if ((TW_STATUS & 0xf8) != TW_START)
+ if (TW_STATUS != TW_START) {
+#ifdef DEBUG
+ printf("I2C: error sending START\n");
+#endif
goto out;
+ }
TWDR = buf[0]; /* SLA_W */
TWCR = ((1<<TWINT) | (1<<TWEN));
while(!(TWCR & (1<<TWINT))) {}
- if ((TW_STATUS & 0xf8) != TW_MT_SLA_ACK)
- goto out;
+ if (TW_STATUS != TW_MT_SLA_ACK) {
+#ifdef DEBUG
+ printf("I2C: error sending SLA_W\n");
+#endif
+ goto out2;
+ }
for(i = 1; i < len; i++) {
TWDR = buf[i]; /* Send Data */
TWCR = ((1<<TWINT) | (1<<TWEN));
while(!(TWCR & (1<<TWINT))) {}
- if ((TW_STATUS & 0xf8) != TW_MT_DATA_ACK)
- goto out;
+ if (TW_STATUS != TW_MT_DATA_ACK) {
+#ifdef DEBUG
+ printf("I2C: error sending DATA byte %d\n", i);
+#endif
+ goto out2;
+ }
}
- TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
- while(!(TWCR & (1<<TWSTO))) {}
-
-#if 1
- /* Timing problem... */
+#ifdef DEBUG
printf("I2C Data sent\n");
#endif
+out2:
+ TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
+ while(TWCR & (1<<TWSTO)) {}
+
out:
- TWDR = 0x00;
- TWCR = old_TWCR;
SREG = old_SREG;
+ TWCR = old_TWCR | (1<<TWINT);
}
ISR (TWI_vect, ISR_BLOCK)
#ifdef DEBUG
printf("I2C: Data received: 0x%02x\n", TWDR);
#endif
+ if (i2c_pos >= sizeof(i2c_databuf)) {
+ TWCR_RESET;
+ i2c_pos = 0x00;
+ break;
+ }
i2c_databuf[i2c_pos] = TWDR;
i2c_pos++;
TWCR_ACK;
TWCR_RESET;
break;
+ case TW_NO_INFO:
+#ifdef DEBUG
+ printf("I2C: TW_NO_INFO received status 0x%2x\n", TW_STATUS);
+#endif
+ TWCR |= (1<<TWINT);
+ break;
+
default:
+#ifdef DEBUG
printf("I2C: Unimplemented status 0x%02x\n", TW_STATUS);
+#endif
TWCR_RESET;
break;
}