X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/rsbs2/blobdiff_plain/453203717769c12e37678c93fcaf4150f2d16a39..989281f290d774ce78f71c8a420870987407a831:/bmc/i2c.c

diff --git a/bmc/i2c.c b/bmc/i2c.c
index f081991..bd4d69c 100644
--- a/bmc/i2c.c
+++ b/bmc/i2c.c
@@ -14,14 +14,24 @@ 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)
@@ -35,36 +45,48 @@ 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)) {}
-
 #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)
@@ -87,6 +109,11 @@ 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;
@@ -102,6 +129,13 @@ ISR (TWI_vect, ISR_BLOCK)
 			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);