open-ameba/RTL00_SDKV35a/example_sources/i2c-shtc1/src/main.c

#include "device.h"
#include "PinNames.h"

#include "basic_types.h"
#include "diag.h" 
#include "osdep_api.h"

#include "i2c_api.h"
#include "pinmap.h"
#include "rtl_lib.h"

#define NO_ERROR        0x00
#define ACK_ERROR       0x01
#define CHECKSUM_ERROR  0x02
#define NULL_ERROR      0x03

#define MBED_I2C_MTR_SDA    PD_4
#define MBED_I2C_MTR_SCL    PD_5

#define MBED_I2C_SLAVE_ADDR0    0x70
#define POLYNOMIAL 0x131 // P(x) = x^8 + x^5 + x^4 + 1 = 100110001


#define MBED_I2C_BUS_CLK        100000  //hz
#define I2C_DATA_MAX_LENGTH     16

uint8_t i2cdata_write[I2C_DATA_MAX_LENGTH];
uint8_t i2cdata_read[I2C_DATA_MAX_LENGTH];
int i2cdata_read_pos;

volatile i2c_t   i2cmaster;


// Sensor Commands
#define READ_ID              0xEFC8 // command: read ID register
#define SOFT_RESET           0x805D // soft resetSample Code for SHTC1
#define MEAS_T_RH_POLLING    0x7866 // meas. read T first, clock stretching disabled
#define MEAS_T_RH_CLOCKSTR   0x7CA2 // meas. read T first, clock stretching enabled
#define MEAS_RH_T_POLLING    0x58E0 // meas. read RH first, clock stretching disabled
#define MEAS_RH_T_CLOCKSTR   0x5C24 // meas. read RH first, clock stretching enabled


static int SHTC1_GetID(uint16_t *id);
static void SHTC1_WriteCommand(uint16_t cmd);
static int SHTC1_Read2BytesAndCrc(uint16_t *data);
static int SHTC1_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum);
static float SHTC1_CalcTemperature(uint16_t rawValue);
static float SHTC1_CalcHumidity(uint16_t rawValue);


int SHTC1_Init(uint16_t *pID)
{
  int error = NO_ERROR;

  DiagPrintf("SHTC1_Init \r\n");

  i2c_init((i2c_t*)&i2cmaster, MBED_I2C_MTR_SDA ,MBED_I2C_MTR_SCL);
  i2c_frequency((i2c_t*)&i2cmaster,MBED_I2C_BUS_CLK);
 
  if (pID == NULL ) return NULL_ERROR;

  
  error = SHTC1_GetID(pID);
  return error;
}

static int SHTC1_GetID(uint16_t *id)
{
  int error = NO_ERROR;
  uint8_t bytes[2];
  uint8_t checksum;

  SHTC1_WriteCommand(READ_ID);  

  i2c_read((i2c_t*)&i2cmaster, MBED_I2C_SLAVE_ADDR0, (char*)&i2cdata_read[0], 3, 1);
  i2cdata_read_pos = 0;
  error = SHTC1_Read2BytesAndCrc(id);

  return error;
}

static int SHTC1_Read2BytesAndCrc(uint16_t *data)
{
  int error;
  int readed;
  uint8_t bytes[2];
  uint8_t checksum;


  
  bytes[0] = i2cdata_read[i2cdata_read_pos++];
  bytes[1] = i2cdata_read[i2cdata_read_pos++];
  checksum = i2cdata_read[i2cdata_read_pos++];

  error = SHTC1_CheckCrc(bytes, 2, checksum);
  *data = (bytes[0] << 8) | bytes[1];  
  
  return error;
}

static int SHTC1_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum)
{
   uint8_t bit; // bit mask
   uint8_t crc = 0xFF; // calculated checksum
   uint8_t byteCtr; // byte counter

   // calculates 8-Bit checksum with given polynomial
   for(byteCtr = 0; byteCtr < nbrOfBytes; byteCtr++)
   {
     crc ^= (data[byteCtr]);
     for(bit = 8; bit > 0; --bit)
     {
       if(crc & 0x80) crc = (crc << 1) ^ POLYNOMIAL;
       else crc = (crc << 1);
     }
  }

   // verify checksum
   if(crc != checksum) return CHECKSUM_ERROR;
   else return NO_ERROR;
}


static void SHTC1_WriteCommand(uint16_t cmd)
{
	int writebytes; 

	i2cdata_write[0] = (uint8_t)(cmd >>8);
	i2cdata_write[1] = (uint8_t)(cmd&0xFF);
  	i2c_write((i2c_t*)&i2cmaster, MBED_I2C_SLAVE_ADDR0, &i2cdata_write[0], 2, 1);
}  

static float SHTC1_CalcTemperature(uint16_t rawValue)
{
  return 175.0 * (float)rawValue / 65536.0 - 45.0;
}

static float SHTC1_CalcHumidity(uint16_t rawValue)
{
  return 100.0 * (float)rawValue / 65536.0;
} 

int SHTC1_GetTempAndHumi(float *temp, float *humi)
{
  int error;
  uint16_t rawValueTemp;
  uint16_t rawValueHumi;
  
  SHTC1_WriteCommand(MEAS_T_RH_CLOCKSTR);  

  //Wire1.requestFrom(I2C_ADR_SHTC1, 6);   
  i2c_read((i2c_t*)&i2cmaster, MBED_I2C_SLAVE_ADDR0, (char*)&i2cdata_read[0], 6, 1);
  i2cdata_read_pos = 0;
  error = NO_ERROR;
  error |= SHTC1_Read2BytesAndCrc(&rawValueTemp);
  error |= SHTC1_Read2BytesAndCrc(&rawValueHumi);

  //diag_printf("raw temp=0x%x, raw humidity=0x%x, error=%d\n", 
  //          rawValueTemp, rawValueHumi, error);
 
  if ( error == NO_ERROR ) {
    *temp = SHTC1_CalcTemperature(rawValueTemp);
    *humi = SHTC1_CalcHumidity(rawValueHumi);
  }
  
  return error;
}


void main(void)
{
    gpio_t gpio_led;
	int led_status;
	int i2clocalcnt;
	int error;
	uint16_t shtc1_id;
	
	float temperature = 1.123f;
	float humidity = 2.456f;


    DBG_8195A("sleep 10 sec. to wait for UART console\n");
	RtlMsleepOS(10000);
	

    DBG_8195A("start i2c example - SHTC1\n");

		
	error = SHTC1_Init(&shtc1_id);
	if ( error == NO_ERROR ) {
	  DiagPrintf("SHTC1 init ok, id=0x%x\r\n", shtc1_id);
	} else {
	  DiagPrintf("SHTC1 init FAILED! \r\n");
	  for(;;);
	}
	
	
	while(1){
		error = SHTC1_GetTempAndHumi(&temperature, &humidity);
		
		rtl_printf("temp=%f, humidity=%f, error=%d\n", 
				  temperature, humidity, error);
		
		RtlMsleepOS(1000);

	}
}