Start working on system initialization

src/bus/twi.c

@@ -13,6 +13,9 @@
 #define  TW_MR_SLA_NACK  0x48
 #define  TW_MR_DATA_ACK  0x50
 
+// XXX: Handle interrupts in TWI_vect ISR? This may not
+// actually be much better than the blocking approach
+
 int TWI_Init(void)
 {
 	// Set SCL bit rate to 400kHz
@@ -23,7 +26,7 @@ int TWI_Init(void)
 	return 0;
 }
 
-int TWI_Start(char addr, char mode)
+int TWI_Start(unsigned char addr, unsigned char mode)
 {
 	unsigned int status;
 
@@ -60,7 +63,7 @@ int TWI_Start(char addr, char mode)
 	return 0;
 }
 
-int TWI_Write(char data)
+int TWI_Write(unsigned char data)
 {
 	TWDR = data;
 	TWCR = (1 << TWEN)    // Enable TWI

src/bus/twi.h

@@ -2,8 +2,8 @@
 #define MAD_CORE_BUS_TWI_H
 
 int TWI_Init(void);
-int TWI_Start(char addr, char mode);
-int TWI_Write(char data);
+int TWI_Start(unsigned char addr, unsigned char mode);
+int TWI_Write(unsigned char data);
 int TWI_Wait_ACK(void);
 int TWI_Stop(void);