Start implementing AHT20 sensor reading

src/bus/twi.c

@@ -77,6 +77,35 @@ int TWI_Write(unsigned char data)
 	return 0;
 }
 
+unsigned char TWI_Read_ACK(void)
+{
+	// Read data and acknowledge
+
+	TWCR = (1 << TWEN)   // Enable TWI
+	     | (1 << TWINT)  // Clear interrupt flag
+	     | (1 << TWEA);  // Send acknowledgment
+
+	// Wait until data read
+
+	while ((TWCR & (1 << TWINT)) == 0);
+
+	return TWDR;
+}
+
+unsigned char TWI_Read_NACK(void)
+{
+	// Read data, expect last byte
+
+	TWCR = (1 << TWEN)    // Enable TWI
+	     | (1 << TWINT);  // Clear interrupt flag
+
+	// Wait until data read
+
+	while ((TWCR & (1 << TWINT)) == 0);
+
+	return TWDR;
+}
+
 int TWI_Wait_ACK(void)
 {
 	unsigned int status;

src/bus/twi.h

@@ -10,6 +10,8 @@ int TWI_Init(void);
 int TWI_Start(unsigned char addr, unsigned char mode);
 int TWI_SetChannel(int channel);
 int TWI_Write(unsigned char data);
+unsigned char TWI_Read_ACK(void);
+unsigned char TWI_Read_NACK(void);
 int TWI_Wait_ACK(void);
 int TWI_Stop(void);