Hi,
I am new to the STM32 and the Standard Peripheral library, so it’s quite likely the mistake I am making in getting I2C to work is simple, but I can’t see it.
I am using a ET-STM32 Stamp (bare metal) board with STM32F103RE6 CPU. I have connected PB6,7 (I2C1) to a LIS3LV02DQ 3-axis accelerometer, which has an I2C interface. I am using CrossWorks 2.0 and the STM32 Standard Peripheral Library V3.1.2.
The code below runs to the point in the first call to I2C_LIS3L_Write (from I2C_LIS3L_Init) where it checks for the EV5 event after I2C_GenerateSTART. This test always fails, the only flag set in the I2C_SR1/2 registers is BUSY. At that same point both the SDA line is low and SCL is high, I don’t see a clock signal on the DSO at all.
The datasheet for the LIS3LV02DQ says it incorporates pull-up resistors for SDA/SCL, which makes it seem odd that SDA is low?
I would welcome any hints on what I am doing wrong.
Thanks
Peter
/* Includes ------------ --------- --------- --------- --------- --------- -*/
#include "stm32f10x.h"
/* Defines for the GPIO pins used for the I2C communication */
#define I2C_LIS3L I2C1
#define I2C_LIS3L_CLK RCC_APB1Periph_ I2C1
#define I2C_LIS3L_GPIO GPIOB
#define I2C_LIS3L_GPIO_ CLK RCC_APB2Periph_ GPIOB
#define I2C_LIS3L_SCL GPIO_Pin_6
#define I2C_LIS3L_SDA GPIO_Pin_7
/* Define a structure for the 16bit Acceleration data */
typedef struct {
uint16_t X_Accel;
uint16_t Y_Accel;
uint16_t Z_Accel;
} LIS3L_AccelTypeDef;
// Physical Device Address - Factory Assigned to 0x3A for LIS3LV02DQ
#define LIS3L_SLAVE_ ADDR 0x3A
// The Who Am I register contains the physical device address
#define LIS3L_WHO_AM_ I 0x0F
// Define the Initialisation code as per the data sheet
#define LIS3L_INIT_CODE 0xC7
// Set CTRL_REG1 to Run Mode, 640Hz data rate and X,Y,Z enabled
#define LIS3L_RUN_CODE 0xE7
// Control registers
#define LIS3L_CTRL_REG1 0x20
#define LIS3L_CTRL_REG2 0x21
// Output data
// X axis acceleration data LSB
#define LIS3L_OUTX_L 0x28
// X axis acceleration data MSB
#define LIS3L_OUTX_H 0x29
// Y axis acceleration data LSB
#define LIS3L_OUTY_L 0x2A
// Y axis acceleration data MSB
#define LIS3L_OUTY_H 0x2B
// Z axis acceleration data LSB
#define LIS3L_OUTZ_L 0x2C
// Z axis acceleration data MSB
#define LIS3L_OUTZ_H 0x2D
/* Function Definitions ------------ --------- --------- --------- --------- ------- */
void I2C_LIS3L_Init( void);
uint8_t I2C_LIS3L_ReadByte( uint8_t ReadAddr);
void I2C_LIS3L_ReadAccel (uint8_t ReadAddr, LIS3L_AccelTypeDef* LIS3L_AccelStruct) ;
void I2C_LIS3L_Write( uint8_t WriteAddr, uint8_t DataByte);
/**
************ ********* ********* ********* ********* ********* ********* ********* ***
* @file lis3l_i2c.c
* @author Peter Lanius
* @version V0.10
* @date 09/12/2009
* @brief This file provides functions to operate the LIS3LV02DQ 3-axis
accelerometer in I2C bus mode.
************ ********* ********* ********* ********* ********* ********* ********* ***
* @copy
*/
/* Includes ------------ --------- --------- --------- --------- --------- -*/
#include "lis3l_i2c.h"
#include "stm32f10x_i2c. h"
/* Private typedef ------------ --------- --------- --------- --------- --------- -*/
/* Private define ------------ --------- --------- --------- --------- --------- -*/
#define I2C_Speed 100000 // 100kHz bus speed (up to 400kHz is ok)
#define I2C_SLAVE_ADDRESS7 0xA0 // I2C own address if in slave mode
/* Private macro ------------ --------- --------- --------- --------- --------- -*/
/* Private variables ------------ --------- --------- --------- --------- --------- */
/* Private function prototypes ------------ --------- --------- --------- --------* /
void GPIO_Configuration( void);
void I2C_Configuration( void);
/* Private functions ------------ --------- --------- --------- --------- --------- */
/**
* @brief Configure the used I/O ports pin
* @param None
* @retval None
*/
void GPIO_Configuration( void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Configure I2C_LIS3L pins: SCL and SDA */
GPIO_InitStructure. GPIO_Pin = I2C_LIS3L_SCL | I2C_LIS3L_SDA;
GPIO_InitStructure. GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure. GPIO_Mode = GPIO_Mode_AF_ OD;
GPIO_Init(I2C_ LIS3L_GPIO, &GPIO_InitStructure );
}
/**
* @brief I2C Configuration
* @param None
* @retval None
*/
void I2C_Configuration( void)
{
I2C_InitTypeDef I2C_InitStructure;
/* I2C configuration */
I2C_InitStructure. I2C_Mode = I2C_Mode_I2C;
I2C_InitStructure. I2C_DutyCycle = I2C_DutyCycle_ 2;
I2C_InitStructure. I2C_OwnAddress1 = I2C_SLAVE_ADDRESS7;
I2C_InitStructure. I2C_Ack = I2C_Ack_Enable;
I2C_InitStructure. I2C_Acknowledged Address = I2C_AcknowledgedAdd ress_7bit;
I2C_InitStructure. I2C_ClockSpeed = I2C_Speed;
/* I2C Peripheral Enable */
I2C_Cmd(I2C_ LIS3L, ENABLE);
/* Apply I2C configuration after enabling it */
I2C_Init(I2C_ LIS3L, &I2C_InitStructure) ;
}
/**
* @brief Initializes peripherals used by the I2C LIS3L driver.
* @param None
* @retval None
*/
#define TxBuffer1Size (countof(TxBuffer1) - 1)
#define TxBuffer2Size (countof(TxBuffer2) - 1)
/* Private macro ------------ --------- --------- --------- --------- --------- -*/
#define countof(a) (sizeof(a) / sizeof(*(a)) )
void I2C_LIS3L_Init( )
{
uint8_t TxBuffer1[] = "\n\rLIS3LV02DQ Initialisation OK.\n\r";
uint8_t TxBuffer2[] = "\n\rLIS3LV02DQ Initialisation FAILED.\n\r" ;
uint8_t TxCounter = 0;
uint8_t lis3l_addr = 0;
/* I2C Periph clock enable */
RCC_APB1PeriphClock Cmd(I2C_LIS3L_ CLK, ENABLE);
/* GPIO Periph clock enable */
RCC_APB2PeriphClock Cmd(I2C_LIS3L_ GPIO_CLK, ENABLE);
/* GPIO configuration */
GPIO_Configuration( );
/* I2C configuration */
I2C_Configuration( );
/* Initialise the device as per data sheet */
I2C_LIS3L_Write( LIS3L_CTRL_ REG1, LIS3L_INIT_CODE) ;
I2C_LIS3L_Write( LIS3L_CTRL_ REG2, 0x00);
/* check everything is ok by reading whoami register */
lis3l_addr = I2C_LIS3L_ReadByte( LIS3L_WHO_ AM_I);
if(lis3l_addr == LIS3L_SLAVE_ ADDR) {
/* Match - Send the relevant message */
while(TxCounter+ + < TxBuffer1Size)
{
USART_SendData( USART1, TxBuffer1[TxCounter -1]);
while(USART_ GetFlagStatus( USART1, USART_FLAG_TXE) == RESET);
}
}
else {
/* Mismatch - Send the relevant message */
while(TxCounter+ + < TxBuffer2Size)
{
USART_SendData( USART1, TxBuffer2[TxCounter -1]);
while(USART_ GetFlagStatus( USART1, USART_FLAG_TXE) == RESET);
}
}
/* Set the data rate to the desired rate */
I2C_LIS3L_Write( LIS3L_CTRL_ REG1, LIS3L_RUN_CODE) ;
}
/**
* @brief Write a byte to the specified register of the LIS3L sensor
* @param WriteAddr : 8bit write address of the LIS3L register
* @param DataByte : byte to write to the specified register
* @retval none
*/
void I2C_LIS3L_Write( uint8_t WriteAddr, uint8_t DataByte)
{
/* Send STRAT condition */
I2C_GenerateSTART( I2C_LIS3L, ENABLE);
/* Test on EV5 and clear it */
while(!I2C_CheckEve nt(I2C_LIS3L, I2C_EVENT_MASTER_ MODE_SELECT) );
/* Send LIS3L address for write */
I2C_Send7bitAddress (I2C_LIS3L, LIS3L_SLAVE_ ADDR, I2C_Direction_ Transmitter) ;
/* Test on EV6 and clear it */
while(!I2C_CheckEve nt(I2C_LIS3L, I2C_EVENT_MASTER_ TRANSMITTER_ MODE_SELECTED) );
/* Send the LIS3L's internal register address to write to */
I2C_SendData( I2C_LIS3L, WriteAddr);
/* Test on EV8 and clear it */
while(!I2C_CheckEve nt(I2C_LIS3L, I2C_EVENT_MASTER_ BYTE_TRANSMITTED ));
/* Send the byte to be written */
I2C_SendData( I2C_LIS3L, DataByte);
/* Test on EV8 and clear it */
while(!I2C_CheckEve nt(I2C_LIS3L, I2C_EVENT_MASTER_ BYTE_TRANSMITTED ));
/* Send STOP condition */
I2C_GenerateSTOP( I2C_LIS3L, ENABLE);
}
