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/* cpu freq */
#define F_CPU 1000000
#include <avr/io.h>
#include <util/delay.h>
#include <util/twi.h>
#include <stdio.h>
/* cpu runs at 1mhz */
/* i2c device addresses */
#define L3GD20 0b11010100
#define L3GD20_WHOAMI 0xf
#define L3GD20_CTRLREG1 0x20
#define LIS302DL 0b00111000
#define LIS302DL_WHOAMI 0xf
#define LIS302DL_CTRLREG1 0x20
void twStart () {
/* disable stop, reset twint, enable start, enable i2c */
TWCR = (TWCR & ~(1 << TWSTO)) | (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
}
void twStop () {
/* disable start, reset twint, enable stop, enable i2c */
TWCR = (TWCR & ~(1 << TWSTA)) | (1 << TWINT) | (1 << TWSTO) | (1 << TWEN);
}
void twFlush () {
/* disable start/stop, reset twint, enable i2c */
TWCR = (TWCR & ~((1 << TWSTA) | (1 << TWSTO))) | (1 << TWINT) | (1 << TWEN);
}
void twWait () {
while (!(TWCR & (1 << TWINT)));
}
void twInit () {
/* set scl to 3.6 kHz (at 1Mhz CPU speed)*/
TWBR = 2;
TWSR |= 0x3; /* set prescaler to 64 */
}
void ledInit () {
/* set led1,led2 to output */
DDRB |= (1 << PB6) | (1 << PB7);
/* set led3,led4,led5,led6 to output */
DDRD |= (1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5);
}
/* show data with leds */
void ledShow (unsigned char val) {
PORTB = (PORTB & ~((1 << PB6) | (1 << PB7))) | ((val & 0x3) << PB6);
PORTD = (PORTD & ~((1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5))) | (((val >> 2) & 0xf) << PD2);
}
void uartInit () {
/* Set baud rate (9600, double speed, at 1mhz) */
UBRR0H = 0;
UBRR0L = 12;
/* enable double speed mode */
UCSR0A = (1 << U2X0);
/* Enable receiver and transmitter */
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
/* Set frame format: 8 data, 1 stop bit, even parity */
UCSR0C = (1<<UPM01) | (0 << UPM00) | (0<<USBS0)|(3<<UCSZ00);
}
/* blocking uart send
*/
void uartSend (unsigned char data) {
/* Wait for empty transmit buffer */
while (!( UCSR0A & (1<<UDRE0)));
/* Put data into buffer, sends the data */
UDR0 = data;
}
int uartPutc (char c, FILE *stream) {
if (c == '\n') {
uartSend ('\r');
}
uartSend (c);
return 0;
}
static FILE mystdout = FDEV_SETUP_STREAM (uartPutc, NULL, _FDEV_SETUP_WRITE);
unsigned char uartReceive () {
/* Wait for data to be received */
while ( !(UCSR0A & (1<<RXC0)) );
/* Get and return received data from buffer */
return UDR0;
}
void cpuInit () {
/* enter change prescaler mode */
CLKPR = CLKPCE << 1;
/* write new prescaler = 8 (i.e. 1Mhz clock frequency) */
CLKPR = 0b00000011;
}
int main(void) {
cpuInit ();
ledInit ();
twInit ();
uartInit ();
/* redirect stdout */
stdout = &mystdout;
printf ("initialization done\n");
/* disable power-down-mode */
twStart ();
twWait ();
unsigned char status = 0x0;
/* check status code */
if ((status = TW_STATUS) == TW_START) {
/* write device address and write bit */
TWDR = LIS302DL | TW_WRITE;
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MT_SLA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
/* write subaddress (actually i2c data) */
TWDR = LIS302DL_CTRLREG1;
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MT_DATA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
/* write actual data */
TWDR = 0b01000111;
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MT_DATA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
twStop ();
_delay_ms (100);
} else {
printf ("write: start failed\n");
}
while (1) {
unsigned char reg[] = {0x29, 0x2b, 0x2d};
signed char val[6];
//unsigned char reg[] = {0xf, 0x20, 0x21, 0x22, 0x23, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2d, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f};
for (unsigned char i = 0; i < sizeof (reg)/sizeof(*reg); i++) {
twStart ();
twWait ();
unsigned char status = 0x0;
/* check status code */
if ((status = TW_STATUS) == TW_START) {
/* write device address and write bit */
TWDR = LIS302DL | TW_WRITE;
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MT_SLA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
/* write subaddress (actually i2c data) */
TWDR = reg[i];
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MT_DATA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
/* repeated start */
twStart ();
twWait ();
if ((status = TW_STATUS) == TW_REP_START) {
} else {
printf ("fail with code %x\n", status);
}
/* write device address and read bit */
TWDR = LIS302DL | TW_READ;
if (TWCR & (1 << TWWC)) {
printf("write collision\n");
}
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MR_SLA_ACK) {
} else {
printf ("fail with code %x\n", status);
}
/* clear twint and wait for response */
twFlush ();
twWait ();
if ((status = TW_STATUS) == TW_MR_DATA_NACK) {
} else {
printf ("fail with code %x\n", status);
}
unsigned char ret = TWDR;
val[i] = ret;
twStop ();
/* there is no way to tell whether stop has been sent or not, just wait */
_delay_ms (10);
} else {
printf ("fail with code %x\n", status);
_delay_ms (1000);
}
}
//printf ("%i/%i/%i\n", (val[1] << 8) | val[0], (val[3] << 8) | val[2], (val[5] << 8) | val[4]);
printf ("%i/%i/%i\n", val[0], val[1], val[2]);
}
while (1);
}
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