X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/rsbs2/blobdiff_plain/87f4338b452dea4fdebba3eac573bec999642eb9..5bece6bf8c66ade0960290b6fe75623da7968e09:/bmc/i2c.c

diff --git a/bmc/i2c.c b/bmc/i2c.c
index f0816f0..07d2e79 100644
--- a/bmc/i2c.c
+++ b/bmc/i2c.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include "i2c.h"
 #include "bmc.h"
+#include "config.h"
 #include "ipmb.h"
 
 #define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);  
@@ -14,9 +15,15 @@ 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));
@@ -78,10 +85,9 @@ out2:
 	TWCR = ((1<<TWINT) | (1<<TWEN) | (1<<TWSTO));
 	while(TWCR & (1<<TWSTO)) {}
 
-	TWCR = (1<<TWINT) | (1<<TWEN);
 out:	
-	TWCR = old_TWCR;
 	SREG = old_SREG;
+	TWCR = old_TWCR | (1<<TWINT);
 }
 
 ISR (TWI_vect, ISR_BLOCK)