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
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);
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
};
}
{
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!
}
{
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();
}
-
--- /dev/null
+/*************************************************************************\r
+* Title: I2C master library using hardware TWI interface\r
+* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury\r
+* File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $\r
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3\r
+* Target: any AVR device with hardware TWI \r
+* Usage: API compatible with I2C Software Library i2cmaster.h\r
+**************************************************************************/\r
+#include <inttypes.h>\r
+#include <compat/twi.h>\r
+#include <util/delay.h>\r
+\r
+#include "twimaster.h"\r
+\r
+\r
+/* define CPU frequency in Mhz here if not defined in Makefile */\r
+#ifndef F_CPU\r
+#define F_CPU 7372800UL\r
+#endif\r
+\r
+/* I2C clock in Hz */\r
+#define SCL_CLOCK 100000L\r
+\r
+\r
+/*************************************************************************\r
+ Initialization of the I2C bus interface. Need to be called only once\r
+*************************************************************************/\r
+void i2c_init(void)\r
+{\r
+ /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */\r
+ \r
+ TWSR |= (1 << TWPS0); /* no prescaler */\r
+ TWBR = ((F_CPU/SCL_CLOCK)-16)/(2*4); /* must be > 10 for stable operation */\r
+\r
+}/* i2c_init */\r
+\r
+\r
+/************************************************************************* \r
+ Issues a start condition and sends address and transfer direction.\r
+ return 0 = device accessible, 1= failed to access device\r
+*************************************************************************/\r
+unsigned char i2c_start(unsigned char address)\r
+{\r
+ uint8_t twst;\r
+\r
+ // send START condition\r
+ TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);\r
+\r
+ // wait until transmission completed\r
+ while(!(TWCR & (1<<TWINT)));\r
+\r
+ // check value of TWI Status Register. Mask prescaler bits.\r
+ twst = TW_STATUS & 0xF8;\r
+ if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;\r
+\r
+ // send device address\r
+ TWDR = address;\r
+ TWCR = (1<<TWINT) | (1<<TWEN);\r
+\r
+ // wail until transmission completed and ACK/NACK has been received\r
+ while(!(TWCR & (1<<TWINT)));\r
+\r
+ // check value of TWI Status Register. Mask prescaler bits.\r
+ twst = TW_STATUS & 0xF8;\r
+ if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;\r
+\r
+ return 0;\r
+\r
+}/* i2c_start */\r
+\r
+\r
+/*************************************************************************\r
+ Issues a start condition and sends address and transfer direction.\r
+ If device is busy, use ack polling to wait until device is ready\r
+ \r
+ FIXME: If device doesn't exist stays in an infinite loop\r
+\r
+ Input: address and transfer direction of I2C device\r
+*************************************************************************/\r
+void i2c_start_wait(unsigned char address)\r
+{\r
+ uint8_t twst;\r
+\r
+\r
+ while ( 1 )\r
+ {\r
+ // send START condition\r
+ TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);\r
+ \r
+ // wait until transmission completed\r
+ while(!(TWCR & (1<<TWINT)));\r
+ \r
+ // check value of TWI Status Register. Mask prescaler bits.\r
+ twst = TW_STATUS & 0xF8;\r
+ if ( (twst != TW_START) && (twst != TW_REP_START)) continue;\r
+ \r
+ // send device address\r
+ TWDR = address;\r
+ TWCR = (1<<TWINT) | (1<<TWEN);\r
+ \r
+ // wail until transmission completed\r
+ while(!(TWCR & (1<<TWINT)));\r
+\r
+ // check value of TWI Status Register. Mask prescaler bits.\r
+ twst = TW_STATUS & 0xF8;\r
+ if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) \r
+ { \r
+ /* device busy, send stop condition to terminate write operation */\r
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);\r
+\r
+ // wait until stop condition is executed and bus released\r
+ while(TWCR & (1<<TWSTO));\r
+ continue;\r
+ }\r
+ break;\r
+ }\r
+\r
+}/* i2c_start_wait */\r
+\r
+\r
+/*************************************************************************\r
+ Issues a repeated start condition and sends address and transfer direction \r
+\r
+ Input: address and transfer direction of I2C device\r
+ \r
+ Return: 0 device accessible\r
+ 1 failed to access device\r
+*************************************************************************/\r
+unsigned char i2c_rep_start(unsigned char address)\r
+{\r
+ return i2c_start( address );\r
+\r
+}/* i2c_rep_start */\r
+\r
+\r
+/*************************************************************************\r
+ Terminates the data transfer and releases the I2C bus\r
+*************************************************************************/\r
+void i2c_stop(void)\r
+{\r
+ /* send stop condition */\r
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);\r
+ \r
+ // wait until stop condition is executed and bus released\r
+ while(TWCR & (1<<TWSTO));\r
+\r
+}/* i2c_stop */\r
+\r
+\r
+/*************************************************************************\r
+ Send one byte to I2C device\r
+ \r
+ Input: byte to be transfered\r
+ Return: 0 write successful \r
+ 1 write failed\r
+*************************************************************************/\r
+unsigned char i2c_write( unsigned char data )\r
+{ \r
+ uint8_t twst;\r
+ \r
+ // send data to the previously addressed device\r
+ TWDR = data;\r
+ TWCR = (1<<TWINT) | (1<<TWEN);\r
+\r
+ // wait until transmission completed\r
+ while(!(TWCR & (1<<TWINT)));\r
+\r
+ // check value of TWI Status Register. Mask prescaler bits\r
+ twst = TW_STATUS & 0xF8;\r
+ if( twst != TW_MT_DATA_ACK) return 1;\r
+ return 0;\r
+\r
+}/* i2c_write */\r
+\r
+\r
+/*************************************************************************\r
+ Read one byte from the I2C device, request more data from device \r
+ \r
+ Return: byte read from I2C device\r
+*************************************************************************/\r
+unsigned char i2c_readAck(void)\r
+{\r
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);\r
+ while(!(TWCR & (1<<TWINT))); \r
+\r
+ return TWDR;\r
+\r
+}/* i2c_readAck */\r
+\r
+\r
+/*************************************************************************\r
+ Read one byte from the I2C device, read is followed by a stop condition \r
+ \r
+ Return: byte read from I2C device\r
+*************************************************************************/\r
+unsigned char i2c_readNak(void)\r
+{\r
+ TWCR = (1<<TWINT) | (1<<TWEN);\r
+ while(!(TWCR & (1<<TWINT)));\r
+ //while(!(TWCR ));\r
+ //_delay_ms(100);\r
+ return TWDR;\r
+\r
+}/* i2c_readNak */\r
--- /dev/null
+#ifndef _I2CMASTER_H\r
+#define _I2CMASTER_H 1\r
+/************************************************************************* \r
+* Title: C include file for the I2C master interface \r
+* (i2cmaster.S or twimaster.c)\r
+* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury\r
+* File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $\r
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3\r
+* Target: any AVR device\r
+* Usage: see Doxygen manual\r
+**************************************************************************/\r
+\r
+#ifdef DOXYGEN\r
+/**\r
+ @defgroup pfleury_ic2master I2C Master library\r
+ @code #include <i2cmaster.h> @endcode\r
+ \r
+ @brief I2C (TWI) Master Software Library\r
+\r
+ Basic routines for communicating with I2C slave devices. This single master \r
+ implementation is limited to one bus master on the I2C bus. \r
+\r
+ This I2c library is implemented as a compact assembler software implementation of the I2C protocol \r
+ which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).\r
+ Since the API for these two implementations is exactly the same, an application can be linked either against the\r
+ software I2C implementation or the hardware I2C implementation.\r
+\r
+ Use 4.7k pull-up resistor on the SDA and SCL pin.\r
+ \r
+ Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module \r
+ i2cmaster.S to your target when using the software I2C implementation ! \r
+ \r
+ Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.\r
+\r
+ @note \r
+ The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted \r
+ to GNU assembler and AVR-GCC C call interface.\r
+ Replaced the incorrect quarter period delays found in AVR300 with \r
+ half period delays. \r
+ \r
+ @author Peter Fleury pfleury@gmx.ch http://jump.to/fleury\r
+\r
+ @par API Usage Example\r
+ The following code shows typical usage of this library, see example test_i2cmaster.c\r
+\r
+ @code\r
+\r
+ #include <i2cmaster.h>\r
+\r
+\r
+ #define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet\r
+\r
+ int main(void)\r
+ {\r
+ unsigned char ret;\r
+\r
+ i2c_init(); // initialize I2C library\r
+\r
+ // write 0x75 to EEPROM address 5 (Byte Write) \r
+ i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode\r
+ i2c_write(0x05); // write address = 5\r
+ i2c_write(0x75); // write value 0x75 to EEPROM\r
+ i2c_stop(); // set stop conditon = release bus\r
+\r
+\r
+ // read previously written value back from EEPROM address 5 \r
+ i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode\r
+\r
+ i2c_write(0x05); // write address = 5\r
+ i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode\r
+\r
+ ret = i2c_readNak(); // read one byte from EEPROM\r
+ i2c_stop();\r
+\r
+ for(;;);\r
+ }\r
+ @endcode\r
+\r
+*/\r
+#endif /* DOXYGEN */\r
+\r
+/**@{*/\r
+\r
+#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304\r
+#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"\r
+#endif\r
+\r
+#include <avr/io.h>\r
+\r
+/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */\r
+#define I2C_READ 1\r
+\r
+/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */\r
+#define I2C_WRITE 0\r
+\r
+\r
+/**\r
+ @brief initialize the I2C master interace. Need to be called only once \r
+ @param void\r
+ @return none\r
+ */\r
+extern void i2c_init(void);\r
+\r
+\r
+/** \r
+ @brief Terminates the data transfer and releases the I2C bus \r
+ @param void\r
+ @return none\r
+ */\r
+extern void i2c_stop(void);\r
+\r
+\r
+/** \r
+ @brief Issues a start condition and sends address and transfer direction \r
+ \r
+ @param addr address and transfer direction of I2C device\r
+ @retval 0 device accessible \r
+ @retval 1 failed to access device \r
+ */\r
+extern unsigned char i2c_start(unsigned char addr);\r
+\r
+\r
+/**\r
+ @brief Issues a repeated start condition and sends address and transfer direction \r
+\r
+ @param addr address and transfer direction of I2C device\r
+ @retval 0 device accessible\r
+ @retval 1 failed to access device\r
+ */\r
+extern unsigned char i2c_rep_start(unsigned char addr);\r
+\r
+\r
+/**\r
+ @brief Issues a start condition and sends address and transfer direction \r
+ \r
+ If device is busy, use ack polling to wait until device ready \r
+ @param addr address and transfer direction of I2C device\r
+ @return none\r
+ */\r
+extern void i2c_start_wait(unsigned char addr);\r
+\r
+ \r
+/**\r
+ @brief Send one byte to I2C device\r
+ @param data byte to be transfered\r
+ @retval 0 write successful\r
+ @retval 1 write failed\r
+ */\r
+extern unsigned char i2c_write(unsigned char data);\r
+\r
+\r
+/**\r
+ @brief read one byte from the I2C device, request more data from device \r
+ @return byte read from I2C device\r
+ */\r
+extern unsigned char i2c_readAck(void);\r
+\r
+/**\r
+ @brief read one byte from the I2C device, read is followed by a stop condition \r
+ @return byte read from I2C device\r
+ */\r
+extern unsigned char i2c_readNak(void);\r
+\r
+/** \r
+ @brief read one byte from the I2C device\r
+ \r
+ Implemented as a macro, which calls either i2c_readAck or i2c_readNak\r
+ \r
+ @param ack 1 send ack, request more data from device<br>\r
+ 0 send nak, read is followed by a stop condition \r
+ @return byte read from I2C device\r
+ */\r
+extern unsigned char i2c_read(unsigned char ack);\r
+#define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak(); \r
+\r
+\r
+/**@}*/\r
+#endif\r
projects / sx / simavr.git / commitdiff