So I recently bought an IMU from Pololu (https://www.pololu.com/product/2738). I've used their old versions of IMUs in the past, but now that I got this new one, I am unable to connect to it via I2C. I am not getting anything at all from the accelerometer. By reading the datasheet, it's only a matter of setting a few registers. When I do that, however, nothing happens. Here's the datasheet of the LSM6DSD33 https://www.pololu.com/file/down...
here's my code:
#define F_CPU 14745600
#define IMU_ADDR 0b1101011 // Gyrosensor + Accelerometer address (1101011)
#define STATUS_REG 0x20
// Accelerometer
#define CTRL9_XL 0x18 // To enable axes
#define CTRL1_XL 0x60 // High-performance mode register
#define INT1_CTRL 0x01 // Acc Data ready interrupt on INT1
#define OUTX_L_XL 0x28 // Acc out X,l
#define OUTX_H_XL 0x29 // Acc out, X,h
#include <stdio.h>
#include <math.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/eeprom.h>
#include <inttypes.h>
#include <util/delay.h>
// C libraries
extern "C"
{
#include "libs/uart.h"
#include "libs/delay.h"
}
// setups TWI (Two Wire Interface A.K.A I2C)
void TWISetup() {
// Set up TWI module to 368,640 Hz
// SCLfreq = Fclock/(16+2*TWBR*(prescaler))
// Set up TWI but rate to 3
TWBR = 3;
// Prescaler to 4
TWSR |= (1 << TWPS0);
// Enable TWI
TWCR |= (1 << TWEN);
}
// Start signal function
void TWIStart() {
// From datasheet page 226
TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN); // Send start condition
while (!(TWCR & (1 << TWINT))); // Wait for TWINT Flag set. This indicates that the START condition has been transmitted
}
void TWIStop() {
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO); // Transmit STOP condition
}
void TWIWrite(uint8_t data) {
//Load SLA_W into TWDR Register. Clear TWINT bit in
//TWCR to start transmission of address
TWDR = data;
TWCR = (1 << TWINT) | (1 << TWEN);
//Wait for TWINT Flag set. This indicates that the SLA+W has
//been transmitted, and ACK/NACK has been received.
while (!(TWCR & (1 << TWINT)));
}
// Read with ACK (Acknowledge bit)
uint8_t TWIReadACK() {
//TWI Interrupt Flag, TWI Enable Bit, TWI Enable Acknowledge Bit
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA);
//Wait for TWINT Flag set.
while (!(TWCR & (1 << TWINT)));
return TWDR;
}
//read byte with NACK
uint8_t TWIReadNACK()
{
TWCR = (1 << TWINT) | (1 << TWEN);
//Wait for TWINT Flag set.
while (!(TWCR & (1 << TWINT)));
return TWDR;
}
// Check status
uint8_t TWIReadStatus() {
uint8_t status;
status = TWSR & 0xF8;
return status;
}
// Read byte
int16_t ReadByte(uint8_t DEVADDR, uint8_t regAddress) {
//send start
TWIStart(); // ST
TWIWrite((DEVADDR << 1) | 0); // SAD+W (Slave address) + Write bit
TWIWrite(regAddress); // Register adddress (SUB)
//send repeated start
TWIStart(); // SR
TWIWrite((DEVADDR << 1) | 1); // SAD + R
int16_t data = TWIReadNACK(); // NMAK
TWIStop(); // SP
return data;
}
// Writes one byte
void writeByte(uint8_t DEVADDR, uint8_t regAddress, uint8_t data) {
TWIStart(); // Starts
TWIWrite((DEVADDR << 1) | 0); // SAD+W (Slave address) + Write bit
TWIWrite(regAddress); // Register adddress (SUB)
TWIWrite(data); // Data to write
TWIStop(); // Stops I2C
}
int main(void)
{
// init serial port
uart_init();
// Serial port
FILE uart_stream;
uart_stream.put = uart_putchar;
uart_stream.get = uart_getchar;
uart_stream.flags = _FDEV_SETUP_RW;
uart_read();
TWISetup();
writeByte(IMU_ADDR,CTRL9_XL, 0b00111000); // X Y Z access enabled
writeByte(IMU_ADDR,CTRL1_XL, 0b01100000); // Acc = 416Hz (High-Performance mode) : ODR_XL [3:0] 0110
writeByte(IMU_ADDR,INT1_CTRL, 0b00000001); // Acc Data Ready interrupt on INT1
uint8_t out_x_a; // Accelerometer output
uint8_t STATUS;
uint8_t MASK = 0b00000001;
printf_P(PSTR("Reading Acc:\r\n")); // "#" Means end of line, "*" is where line begins
while (1) {
STATUS = ReadByte(IMU_ADDR, STATUS_REG);
uint8_t STATUS_LSB = STATUS & MASK; // Get the last bit status
if (STATUS_LSB) // Read LSB
{
printf_P(PSTR("Output Acc")); // "#" Means end of line, "*" is where line begins
out_x_a = ReadByte(IMU_ADDR, OUTX_L_XL);
printf_P(PSTR(": %d\r\n"), out_x_a); // "#" Means end of line, "*" is where line begins
}
else {
}
}
return 0;
}
According to the dasheet settng the registers is the only thing needed to power on accelerometer
Then it says something about using the STATUS register to expect new data, which I am using too.
So basically I am doing everything I should be doing according to the datasheet... The i2c code I am using should work well on the atmega328p, it's the one I've been using for a while for another IMU... Anyone have worked with the LSM6DSD33? Thanks!
