I am working with DS18b20 temperature sensor in STM32L073RZ board. DS18b20 works using one wire communication. I used one GPIO pin for communicate with DS18b20. i couldn't get the sensor reading. i have attached my code below. Thanks in advance.
static void DS18B20_Mode_OUT_PP(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Pin = BSP_DS18B20_PIN;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(BSP_DS18B20_PORT, &GPIO_InitStruct);
}
static void DS18B20_Mode_IN_NP(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.Pin = BSP_DS18B20_PIN;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(BSP_DS18B20_PORT, &GPIO_InitStruct);
}
static void DS18B20_Reset(void)
{
DS18B20_Mode_OUT_PP();
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, 0);
bsp_delay_us (480);
HAL_GPIO_WritePin(BSP_DS18B20_PORT, BSP_DS18B20_PIN, GPIO_PIN_SET);
bsp_delay_us(80);
}
static uint8_t DS18B20_Presence(void)
{
uint8_t pulse_time = 0;
DS18B20_Mode_IN_NP();
bsp_delay_us(60);
while (!(DS18B20_IN) && (pulse_time <100))
{
pulse_time++;
bsp_delay_us(1);
}
//bsp_delay_us(350);
if (pulse_time >= 99)
{
DS18B20_Mode_OUT_PP();
return 1;
}
else
{
//pulse_time = 0;
return 0;
}
}
uint8_t DS18B20_Init(void)
{
DS18B20_Reset();
return DS18B20_Presence();
}
static uint8_t DS18B20_ReadBit(void)
{
uint8_t dat;
DS18B20_Mode_OUT_PP();
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, 0);
bsp_delay_us(2);
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, SET);
DS18B20_Mode_IN_NP();
bsp_delay_us(8);
if (DS18B20_IN)
{
dat = 1;
count1=count1+1;
}
else
{
dat = 0;
count2=count2+1;
}
bsp_delay_us(60);
d=dat;
return dat;
}
static uint8_t DS18B20_ReadByte(void)
{
uint8_t i, j, dat = 0;
for(i = 0; i < 8; i++)
{
j = DS18B20_ReadBit();
dat = (dat) | (j << i);
}
n=dat;
return dat;
}
static void DS18B20_WriteByte(uint8_t dat)
{
uint8_t i ;//testb
DS18B20_Mode_OUT_PP(); // set as output
for (int i=0; i<8; i++)
{
if ((dat & (1<<i))!=0) // if the bit is high
{
// write 1
DS18B20_Mode_OUT_PP(); // set as output
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, 0); // pull the pin LOW
bsp_delay_us (5); // wait for 1 us
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, SET); // set as input
bsp_delay_us (60); // wait for 60 us
}
else // if the bit is low
{
count4 = count4+1;
DS18B20_Mode_OUT_PP();
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, 0); // pull the pin LOW
bsp_delay_us(60); // wait for 60 us
HAL_GPIO_WritePin (BSP_DS18B20_PORT, BSP_DS18B20_PIN, SET);
bsp_delay_us(5);
}
}
}
static void DS18B20_SkipRom(void)
{
DS18B20_WriteByte(0XCC); /* Skip ROM */
}
float DS18B20_GetTemp_SkipRom(void)
{
uint8_t tpmsb, tplsb;
float s_tem;
DS18B20_SkipRom();
DS18B20_WriteByte(0X44); /* Start conversion */
bsp_delay_us(75000);
DS18B20_Reset();
DS18B20_Presence();
DS18B20_SkipRom();
DS18B20_WriteByte(0XBE); /* read temperature value */
tplsb = DS18B20_ReadByte();
tpmsb = DS18B20_ReadByte();
s_tem = (tpmsb<<8)|tplsb;
s_tem = s_tem/16;
m=tplsb;
return s_tem;
}
void DS18B20_ReadId(uint8_t *ds18b20_id)
{
uint8_t uc;
DS18B20_WriteByte(0x33); //Read the serial number
for (uc = 0; uc < 8; uc++)
{
ds18b20_id[uc] = DS18B20_ReadByte();
}
}
void bsp_delay_us(uint16_t us)
{
__HAL_TIM_SET_COUNTER(&htim6, 0);
HAL_TIM_Base_Start(&htim6);
while (__HAL_TIM_GET_COUNTER(&htim6) != us);
HAL_TIM_Base_Stop(&htim6);
}
float ReadTemperature(void){
DS18B20_Init();
DS18B20_ReadId(ucDs18b20Id);
float value = 0;
float temp_val;
temp_val=DS18B20_GetTemp_SkipRom();
value+=temp_val;
count=count+1;
return value;
}
