From: Doug Szumski <d.s.szumski@gmail.com>
Date: Thu, 4 Sep 2014 20:54:25 +0000 (+0200)
Subject: examples: Extends i2ctest to include a second TWI driver
X-Git-Tag: v1.3~70^2
X-Git-Url: https://git.htl-mechatronik.at/public/?a=commitdiff_plain;h=2190f69580c71bc715a9dd24c27ebcd81d53b29b;p=sx%2Fsimavr.git

examples: Extends i2ctest to include a second TWI driver

Adds a commonly used alternative to the Atmel TWI driver. This
particular driver is choosen because it covers a non-interrupt
driven approach to using the TWI module.
---

diff --git a/examples/board_i2ctest/Makefile b/examples/board_i2ctest/Makefile
index ec0197b..73d8983 100644
--- a/examples/board_i2ctest/Makefile
+++ b/examples/board_i2ctest/Makefile
@@ -36,7 +36,7 @@ all: obj ${firmware} ${target}
 
 include ${simavr}/Makefile.common
 
-atmega1280_${target}.axf: atmega1280_${target}.c
+atmega1280_${target}.axf: atmega1280_${target}.c twimaster.c
 atmega1280_${target}.axf: ${simavr}/examples/shared/avr_twi_master.c
 atmega1280_${target}.axf: ${simavr}/examples/shared/avr_twi_master.h
 
diff --git a/examples/board_i2ctest/atmega1280_i2ctest.c b/examples/board_i2ctest/atmega1280_i2ctest.c
index e40e73f..8bab174 100644
--- a/examples/board_i2ctest/atmega1280_i2ctest.c
+++ b/examples/board_i2ctest/atmega1280_i2ctest.c
@@ -28,9 +28,12 @@
 AVR_MCU(F_CPU, "atmega1280");
 
 #include "../shared/avr_twi_master.h"
+#include "../shared/twimaster.h"
 
 #include <stdio.h>
 
+#define EEPROM_ADDR	0xA0
+
 static int uart_putchar(char c, FILE *stream) {
   if (c == '\n')
     uart_putchar('\r', stream);
@@ -42,17 +45,14 @@ static int uart_putchar(char c, FILE *stream) {
 static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL,
                                          _FDEV_SETUP_WRITE);
 
-int main()
+static void
+test_twi_with_atmel_driver(void)
 {
-	stdout = &mystdout;
-
-	sei();
-
 	TWI_Master_Initialise();
 
 	{	// write 2 bytes at some random address
 		uint8_t msg[8] = {
-				0xa0, // TWI address,
+				EEPROM_ADDR, // TWI address,
 				0xaa, 0x01, // eeprom address, in little endian
 				0xde, 0xad,	// data bytes
 		};
@@ -63,7 +63,7 @@ int main()
 	}
 	{
 		uint8_t msg[8] = {
-				0xa0, // TWI address,
+				EEPROM_ADDR, // TWI address,
 				0xa8, 0x01, // eeprom address, in little endian
 		};
 		TWI_Start_Transceiver_With_Data(msg, 3, 0); // dont send stop!
@@ -73,14 +73,68 @@ int main()
 	}
 	{
 		uint8_t msg[9] = {
-				0xa0 + 1, // TWI address,
+				EEPROM_ADDR + 1, // TWI address,
 		};
 		TWI_Start_Transceiver_With_Data(msg, 9, 1); // write 1 byte, read 8, send stop
 
 		while (TWI_Transceiver_Busy())
 			sleep_mode();
 	}
+}
+
+/*
+ * Tests the TWI using a commonly used and non-interrupt driven
+ * alternative to the Atmel driver:
+ *
+ * "I2C master library using hardware TWI interface"
+ * Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
+ */
+static void
+test_twi_with_pf_driver(void)
+{
+	/*
+	 * This init followed by a start condition is enough to overwrite all TWI
+	 * related bits set by TWI_Master_Initialise () in the Atmel driver.
+	 */
+	i2c_init();
+
+	i2c_start(EEPROM_ADDR + I2C_WRITE);
+	// eeprom address, in little endian
+	i2c_write(0xaa);
+	i2c_write(0x01);
+	// data bytes
+	i2c_write(0xd0);
+	i2c_write(0x0d);
+	i2c_stop();
+
+	i2c_start(EEPROM_ADDR + I2C_WRITE);
+	// set address
+	i2c_write(0xa8);
+	i2c_write(0x01);
+	// Don't stop
+
+	// Read back data
+	i2c_start (EEPROM_ADDR + I2C_READ);
+	for (uint8_t i = 0; i < 8; ++i) {
+		i2c_readNak();
+	};
+	i2c_stop();
+}
+
+int main()
+{
+	stdout = &mystdout;
+
+	sei();
+
+	test_twi_with_atmel_driver();
+
+	/*
+	 * This should produce *exactly* the same output as above, except
+	 * the data written should be D00D as opposed to DEAD.
+	 */
+	test_twi_with_pf_driver ();
+
 	cli();
 	sleep_mode();
 }
-
diff --git a/examples/shared/twimaster.c b/examples/shared/twimaster.c
new file mode 100755
index 0000000..43925b3
--- /dev/null
+++ b/examples/shared/twimaster.c
@@ -0,0 +1,204 @@
+/*************************************************************************
+* Title:    I2C master library using hardware TWI interface
+* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
+* File:     $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
+* Target:   any AVR device with hardware TWI 
+* Usage:    API compatible with I2C Software Library i2cmaster.h
+**************************************************************************/
+#include <inttypes.h>
+#include <compat/twi.h>
+#include <util/delay.h>
+
+#include "twimaster.h"
+
+
+/* define CPU frequency in Mhz here if not defined in Makefile */
+#ifndef F_CPU
+#define F_CPU 7372800UL
+#endif
+
+/* I2C clock in Hz */
+#define SCL_CLOCK  100000L
+
+
+/*************************************************************************
+ Initialization of the I2C bus interface. Need to be called only once
+*************************************************************************/
+void i2c_init(void)
+{
+  /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */
+  
+  TWSR |= (1 << TWPS0);                         /* no prescaler */
+  TWBR = ((F_CPU/SCL_CLOCK)-16)/(2*4);  /* must be > 10 for stable operation */
+
+}/* i2c_init */
+
+
+/*************************************************************************	
+  Issues a start condition and sends address and transfer direction.
+  return 0 = device accessible, 1= failed to access device
+*************************************************************************/
+unsigned char i2c_start(unsigned char address)
+{
+    uint8_t   twst;
+
+	// send START condition
+	TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+
+	// wait until transmission completed
+	while(!(TWCR & (1<<TWINT)));
+
+	// check value of TWI Status Register. Mask prescaler bits.
+	twst = TW_STATUS & 0xF8;
+	if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;
+
+	// send device address
+	TWDR = address;
+	TWCR = (1<<TWINT) | (1<<TWEN);
+
+	// wail until transmission completed and ACK/NACK has been received
+	while(!(TWCR & (1<<TWINT)));
+
+	// check value of TWI Status Register. Mask prescaler bits.
+	twst = TW_STATUS & 0xF8;
+	if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
+
+	return 0;
+
+}/* i2c_start */
+
+
+/*************************************************************************
+ Issues a start condition and sends address and transfer direction.
+ If device is busy, use ack polling to wait until device is ready
+ 
+ FIXME: If device doesn't exist stays in an infinite loop
+
+ Input:   address and transfer direction of I2C device
+*************************************************************************/
+void i2c_start_wait(unsigned char address)
+{
+    uint8_t   twst;
+
+
+    while ( 1 )
+    {
+	    // send START condition
+	    TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+    
+    	// wait until transmission completed
+    	while(!(TWCR & (1<<TWINT)));
+    
+    	// check value of TWI Status Register. Mask prescaler bits.
+    	twst = TW_STATUS & 0xF8;
+    	if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
+    
+    	// send device address
+    	TWDR = address;
+    	TWCR = (1<<TWINT) | (1<<TWEN);
+    
+    	// wail until transmission completed
+    	while(!(TWCR & (1<<TWINT)));
+
+    	// check value of TWI Status Register. Mask prescaler bits.
+    	twst = TW_STATUS & 0xF8;
+    	if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) 
+    	{    	    
+    	    /* device busy, send stop condition to terminate write operation */
+	        TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+
+	        // wait until stop condition is executed and bus released
+	        while(TWCR & (1<<TWSTO));
+    	    continue;
+    	}
+    	break;
+     }
+
+}/* i2c_start_wait */
+
+
+/*************************************************************************
+ Issues a repeated start condition and sends address and transfer direction 
+
+ Input:   address and transfer direction of I2C device
+ 
+ Return:  0 device accessible
+          1 failed to access device
+*************************************************************************/
+unsigned char i2c_rep_start(unsigned char address)
+{
+    return i2c_start( address );
+
+}/* i2c_rep_start */
+
+
+/*************************************************************************
+ Terminates the data transfer and releases the I2C bus
+*************************************************************************/
+void i2c_stop(void)
+{
+    /* send stop condition */
+	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+	
+	// wait until stop condition is executed and bus released
+	while(TWCR & (1<<TWSTO));
+
+}/* i2c_stop */
+
+
+/*************************************************************************
+  Send one byte to I2C device
+  
+  Input:    byte to be transfered
+  Return:   0 write successful 
+            1 write failed
+*************************************************************************/
+unsigned char i2c_write( unsigned char data )
+{	
+    uint8_t   twst;
+    
+	// send data to the previously addressed device
+	TWDR = data;
+	TWCR = (1<<TWINT) | (1<<TWEN);
+
+	// wait until transmission completed
+	while(!(TWCR & (1<<TWINT)));
+
+	// check value of TWI Status Register. Mask prescaler bits
+	twst = TW_STATUS & 0xF8;
+	if( twst != TW_MT_DATA_ACK) return 1;
+	return 0;
+
+}/* i2c_write */
+
+
+/*************************************************************************
+ Read one byte from the I2C device, request more data from device 
+ 
+ Return:  byte read from I2C device
+*************************************************************************/
+unsigned char i2c_readAck(void)
+{
+	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
+	while(!(TWCR & (1<<TWINT)));    
+
+    return TWDR;
+
+}/* i2c_readAck */
+
+
+/*************************************************************************
+ Read one byte from the I2C device, read is followed by a stop condition 
+ 
+ Return:  byte read from I2C device
+*************************************************************************/
+unsigned char i2c_readNak(void)
+{
+	TWCR = (1<<TWINT) | (1<<TWEN);
+	while(!(TWCR & (1<<TWINT)));
+    //while(!(TWCR ));
+	//_delay_ms(100);
+    return TWDR;
+
+}/* i2c_readNak */
diff --git a/examples/shared/twimaster.h b/examples/shared/twimaster.h
new file mode 100755
index 0000000..70f51fd
--- /dev/null
+++ b/examples/shared/twimaster.h
@@ -0,0 +1,178 @@
+#ifndef _I2CMASTER_H
+#define _I2CMASTER_H   1
+/************************************************************************* 
+* Title:    C include file for the I2C master interface 
+*           (i2cmaster.S or twimaster.c)
+* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
+* File:     $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
+* Target:   any AVR device
+* Usage:    see Doxygen manual
+**************************************************************************/
+
+#ifdef DOXYGEN
+/**
+ @defgroup pfleury_ic2master I2C Master library
+ @code #include <i2cmaster.h> @endcode
+  
+ @brief I2C (TWI) Master Software Library
+
+ Basic routines for communicating with I2C slave devices. This single master 
+ implementation is limited to one bus master on the I2C bus. 
+
+ This I2c library is implemented as a compact assembler software implementation of the I2C protocol 
+ which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).
+ Since the API for these two implementations is exactly the same, an application can be linked either against the
+ software I2C implementation or the hardware I2C implementation.
+
+ Use 4.7k pull-up resistor on the SDA and SCL pin.
+ 
+ Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module 
+ i2cmaster.S to your target when using the software I2C implementation ! 
+ 
+ Adjust the  CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.
+
+ @note 
+    The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted 
+    to GNU assembler and AVR-GCC C call interface.
+    Replaced the incorrect quarter period delays found in AVR300 with 
+    half period delays. 
+    
+ @author Peter Fleury pfleury@gmx.ch  http://jump.to/fleury
+
+ @par API Usage Example
+  The following code shows typical usage of this library, see example test_i2cmaster.c
+
+ @code
+
+ #include <i2cmaster.h>
+
+
+ #define Dev24C02  0xA2      // device address of EEPROM 24C02, see datasheet
+
+ int main(void)
+ {
+     unsigned char ret;
+
+     i2c_init();                             // initialize I2C library
+
+     // write 0x75 to EEPROM address 5 (Byte Write) 
+     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
+     i2c_write(0x05);                        // write address = 5
+     i2c_write(0x75);                        // write value 0x75 to EEPROM
+     i2c_stop();                             // set stop conditon = release bus
+
+
+     // read previously written value back from EEPROM address 5 
+     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
+
+     i2c_write(0x05);                        // write address = 5
+     i2c_rep_start(Dev24C02+I2C_READ);       // set device address and read mode
+
+     ret = i2c_readNak();                    // read one byte from EEPROM
+     i2c_stop();
+
+     for(;;);
+ }
+ @endcode
+
+*/
+#endif /* DOXYGEN */
+
+/**@{*/
+
+#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
+#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
+#endif
+
+#include <avr/io.h>
+
+/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */
+#define I2C_READ    1
+
+/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */
+#define I2C_WRITE   0
+
+
+/**
+ @brief initialize the I2C master interace. Need to be called only once 
+ @param  void
+ @return none
+ */
+extern void i2c_init(void);
+
+
+/** 
+ @brief Terminates the data transfer and releases the I2C bus 
+ @param void
+ @return none
+ */
+extern void i2c_stop(void);
+
+
+/** 
+ @brief Issues a start condition and sends address and transfer direction 
+  
+ @param    addr address and transfer direction of I2C device
+ @retval   0   device accessible 
+ @retval   1   failed to access device 
+ */
+extern unsigned char i2c_start(unsigned char addr);
+
+
+/**
+ @brief Issues a repeated start condition and sends address and transfer direction 
+
+ @param   addr address and transfer direction of I2C device
+ @retval  0 device accessible
+ @retval  1 failed to access device
+ */
+extern unsigned char i2c_rep_start(unsigned char addr);
+
+
+/**
+ @brief Issues a start condition and sends address and transfer direction 
+   
+ If device is busy, use ack polling to wait until device ready 
+ @param    addr address and transfer direction of I2C device
+ @return   none
+ */
+extern void i2c_start_wait(unsigned char addr);
+
+ 
+/**
+ @brief Send one byte to I2C device
+ @param    data  byte to be transfered
+ @retval   0 write successful
+ @retval   1 write failed
+ */
+extern unsigned char i2c_write(unsigned char data);
+
+
+/**
+ @brief    read one byte from the I2C device, request more data from device 
+ @return   byte read from I2C device
+ */
+extern unsigned char i2c_readAck(void);
+
+/**
+ @brief    read one byte from the I2C device, read is followed by a stop condition 
+ @return   byte read from I2C device
+ */
+extern unsigned char i2c_readNak(void);
+
+/** 
+ @brief    read one byte from the I2C device
+ 
+ Implemented as a macro, which calls either i2c_readAck or i2c_readNak
+ 
+ @param    ack 1 send ack, request more data from device<br>
+               0 send nak, read is followed by a stop condition 
+ @return   byte read from I2C device
+ */
+extern unsigned char i2c_read(unsigned char ack);
+#define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak(); 
+
+
+/**@}*/
+#endif