Initial commit

twi_master.c

@@ -0,0 +1,232 @@
+/*
+ * twi_master.c
+ *
+ * Created: 09-Jun-19 11:20:17 AM
+ *  Author: TEP SOVICHEA
+ */ 
+
+#include "twi_master.h"
+
+static ret_code_t tw_start(void)
+{
+	/* Send START condition */
+#if DEBUG_LOG
+	printf(BG "Send START condition..." RESET);
+#endif
+	TWCR =  (1 << TWINT) | (1 << TWEN) | (1 << TWSTA);
+	
+	/* Wait for TWINT flag to set */
+	while (!(TWCR & (1 << TWINT)));
+	
+	/* Check error */
+	if (TW_STATUS != TW_START && TW_STATUS != TW_REP_START)
+	{
+#if DEBUG_LOG
+		printf("\n");
+#endif
+		return TW_STATUS;
+	}
+	
+#if DEBUG_LOG
+	printf("SUCCESS\n");
+#endif
+	return SUCCESS;
+}
+
+
+static void tw_stop(void)
+{
+	/* Send STOP condition */
+#if DEBUG_LOG
+	puts(BG "Send STOP condition." RESET);
+#endif
+	TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
+}
+
+
+static ret_code_t tw_write_sla(uint8_t sla)
+{
+	/* Transmit slave address with read/write flag */
+#if DEBUG_LOG
+	printf(BG "Write SLA + R/W: 0x%02X..." RESET, sla);
+#endif
+	TWDR = sla;
+	TWCR = (1 << TWINT) | (1 << TWEN);
+	
+	/* Wait for TWINT flag to set */
+	while (!(TWCR & (1 << TWINT)));
+	if (TW_STATUS != TW_MT_SLA_ACK && TW_STATUS != TW_MR_SLA_ACK)
+	{
+#if DEBUG_LOG
+	printf("\n");
+#endif
+		return TW_STATUS;
+	}
+
+#if DEBUG_LOG
+	printf("SUCCESS\n");
+#endif
+	return SUCCESS;
+}
+
+
+static ret_code_t tw_write(uint8_t data)
+{
+	/* Transmit 1 byte*/
+#if DEBUG_LOG
+	printf(BG "Write data byte: 0x%02X..." RESET, data);
+#endif
+	TWDR = data;
+	TWCR = (1 << TWINT) | (1 << TWEN);
+	
+	/* Wait for TWINT flag to set */
+	while (!(TWCR & (1 << TWINT)));
+	if (TW_STATUS != TW_MT_DATA_ACK)
+	{
+#if DEBUG_LOG
+		printf("\n");
+#endif
+		return TW_STATUS;
+	}
+	
+#if DEBUG_LOG
+	printf("SUCCESS\n");
+#endif
+	return SUCCESS;
+}
+
+
+static uint8_t tw_read(bool read_ack)
+{
+	if (read_ack)
+	{
+		TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA);
+		while (!(TWCR & (1 << TWINT)));
+		if (TW_STATUS != TW_MR_DATA_ACK)
+		{
+			return TW_STATUS;
+		}
+	}
+	else
+	{
+		TWCR = (1 << TWINT) | (1 << TWEN);
+		while (!(TWCR & (1 << TWINT)));
+		if (TW_STATUS != TW_MR_DATA_NACK)
+		{
+			return TW_STATUS;
+		}
+	}
+	uint8_t data = TWDR;
+#if DEBUG_LOG
+	printf(BG "Read data byte: 0x%02X\n" RESET, data);
+#endif
+	return data;
+}
+
+
+void tw_init(twi_freq_mode_t twi_freq_mode, bool pullup_en)
+{
+	DDRC  |= (1 << TW_SDA_PIN) | (1 << TW_SCL_PIN);
+	if (pullup_en)
+	{
+#if DEBUG_LOG
+		puts(BG "Enable pull-up resistor." RESET);
+#endif
+		PORTC |= (1 << TW_SDA_PIN) | (1 << TW_SCL_PIN);
+	}
+	else
+	{
+		PORTC &= ~((1 << TW_SDA_PIN) | (1 << TW_SCL_PIN));
+	}
+	DDRC  &= ~((1 << TW_SDA_PIN) | (1 << TW_SCL_PIN));
+	
+	switch (twi_freq_mode)
+	{
+		case TW_FREQ_100K:
+		/* Set bit rate register 72 and prescaler to 1 resulting in
+		SCL_freq = 16MHz/(16 + 2*72*1) = 100KHz	*/
+		TWBR = 72;
+		break;
+	
+		case TW_FREQ_250K:
+		/* Set bit rate register 24 and prescaler to 1 resulting in
+		SCL_freq = 16MHz/(16 + 2*24*1) = 250KHz	*/		
+		TWBR = 24;
+		break;
+		
+		case TW_FREQ_400K:
+		/* Set bit rate register 12 and prescaler to 1 resulting in
+		SCL_freq = 16MHz/(16 + 2*12*1) = 400KHz	*/
+		TWBR = 12;
+		break;
+		
+		default: break;
+	}
+}
+
+
+ret_code_t tw_master_transmit(uint8_t slave_addr, uint8_t* p_data, uint8_t len)
+{
+	ret_code_t error_code;
+	
+	/* Send START condition */
+	error_code = tw_start();
+	if (error_code != SUCCESS)
+	{
+		return error_code;
+	}
+	
+	/* Send slave address with WRITE flag */
+	error_code = tw_write_sla(TW_SLA_W(slave_addr));
+	if (error_code != SUCCESS)
+	{
+		return error_code;
+	}
+	
+	/* Send data byte in single or burst mode */
+	for (int i = 0; i < len; ++i)
+	{	
+		error_code = tw_write(p_data[i]);
+		if (error_code != SUCCESS)
+		{
+			return error_code;
+		}
+	}
+	
+	/* Send STOP condition */
+	tw_stop();
+	
+	return SUCCESS;
+}
+
+
+ret_code_t tw_master_receive(uint8_t slave_addr, uint8_t* p_data, uint8_t len)
+{
+	ret_code_t error_code;
+	
+	/* Send START condition */
+	error_code = tw_start();
+	if (error_code != SUCCESS)
+	{
+		return error_code;
+	}
+	
+	/* Write slave address with READ flag */
+	error_code = tw_write_sla(TW_SLA_R(slave_addr));
+	if (error_code != SUCCESS)
+	{
+		return error_code;
+	}
+	
+	/* Read single or multiple data byte and send ack */
+	for (int i = 0; i < len-1; ++i)
+	{
+		p_data[i] = tw_read(TW_READ_ACK);
+	}
+	p_data[len-1] = tw_read(TW_READ_NACK);
+	
+	/* Send STOP condition */
+	tw_stop();
+	
+	return SUCCESS;
+}

twi_master.h

@@ -0,0 +1,39 @@
+/*
+ * twi_master.h
+ *
+ * Created: 09-Jun-19 11:20:04 AM
+ *  Author: TEP SOVICHEA
+ */ 
+
+
+#ifndef TWI_MASTER_H_
+#define TWI_MASTER_H_
+#include <avr/io.h>
+#include <util/twi.h>
+#include <stdbool.h>
+#include "uart.h"
+
+#define DEBUG_LOG			0
+#define SUCCESS				0
+
+#define TW_SCL_PIN			PORTC5
+#define TW_SDA_PIN			PORTC4
+
+#define TW_SLA_W(ADDR)		((ADDR << 1) | TW_WRITE)
+#define TW_SLA_R(ADDR)		((ADDR << 1) | TW_READ)
+#define TW_READ_ACK			1
+#define TW_READ_NACK		0
+
+typedef uint16_t ret_code_t;
+
+typedef enum {
+	TW_FREQ_100K,
+	TW_FREQ_250K,
+	TW_FREQ_400K
+} twi_freq_mode_t;
+
+void tw_init(twi_freq_mode_t twi_freq, bool pullup_en);
+ret_code_t tw_master_transmit(uint8_t addr, uint8_t* p_data, uint8_t len);
+ret_code_t tw_master_receive(uint8_t addr, uint8_t* p_data, uint8_t len);
+
+#endif /* TWI_MASTER_H_ */