//----------------------------------------------------------------------------------
u8 s_measure(u16 *p_value, u16 *p_checksum, u8 mode)
//----------------------------------------------------------------------------------
// makes a measurement (humidity/temperature) with checksum
{
unsigned short error=0;
// unsigned int i;
u16 sht11_msb, sht11_lsb;
s_transstart(); //transmission start
switch(mode){ //send command to sensor
case TEMP : error+=s_write_byte(MEASURE_TEMP); break;
case HUMI : error+=s_write_byte(MEASURE_HUMI); break;
default : break;
}
if(error != 0){return error;}
/* Enable External_Interrupt1 of SHT11. */
MAKE_I2CDATA_INPUT();
//SHT11_INTERRUPT_ENABLE();
while(1){ sht11_delay(500); if(READ_I2CDATA_PIN() == 0) break; }
MAKE_I2CDATA_INPUT();
sht11_msb = s_read_byte(ACK); //read the first byte (MSB)
sht11_lsb = s_read_byte(ACK); //read the second byte (LSB)
*p_value = (sht11_msb * 256) + sht11_lsb;
*p_checksum =s_read_byte(noACK); //read checksum
acq_complete = false;
return error;
}
bool sht11_write(SHT11_t *structure, unsigned char cmd, unsigned char *status_reg) {
/*
* If flag busy is true, signify that a command has been already send
* and now we will wait to read data.
* If flag busy is true will return true, to return signal that the command is send
* and now we will wait for response.
*/
if(structure->busy) return true;
/*
* This is the single case that this function run forward.
* This will go on only if a is called for first time, response is read
* nack is received or timeout is occurred.
* Now will set the timeout in millisecond and send the command.
*/
timer_interval(&structure->Timeout_Timer, 500);
structure->busy = true;
gpio_function_set(structure->Scl, GPIO_OUT_OPEN_DRAIN);
gpio_function_set(structure->Sda, GPIO_OUT_OPEN_DRAIN);
/* Send transmission start.
* ___ ___
* data = \_____/
* ___ ___
* clk = _/ \_/ \__
*/
gpio_out(structure->Scl, 0);
sht11_delay(structure);
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Sda, 0);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Sda, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
/*
* Send command.
*/
unsigned char data_cnt = 0;
unsigned char _cmd = cmd;
for(; data_cnt < 8; data_cnt++) {
if(_cmd & 0x80)
gpio_out(structure->Sda, 1);
else
gpio_out(structure->Sda, 0);
sht11_delay(structure);
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
if(data_cnt == 7) {
gpio_out(structure->Sda, 1);
gpio_function_set(structure->Sda, GPIO_IN_PULL_UP);
}
sht11_delay(structure);
_cmd = _cmd << 1;
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
signed int ack = gpio_in(structure->Sda);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
if(ack) {
structure->busy = false;
return false;
}
structure->reg_inst = cmd;
if(cmd == SHT11_WRITE_STATUS_REG) {
/*
* Write status register
*/
gpio_function_set(structure->Sda, GPIO_OUT_OPEN_DRAIN);
unsigned char st_reg = *status_reg;
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
if(st_reg & 0x80)
gpio_out(structure->Sda, 1);
else
gpio_out(structure->Sda, 0);
sht11_delay(structure);
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
if(data_cnt == 7) {
gpio_out(structure->Sda, 1);
gpio_function_set(structure->Sda, GPIO_IN_PULL_UP);
}
sht11_delay(structure);
st_reg = st_reg << 1;
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
signed int ack = gpio_in(structure->Sda);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
if(ack) {
structure->busy = false;
return false;
}
structure->busy = false;
} else if(cmd == SHT11_READ_STATUS_REG) {
/*
* Read status register.
*/
unsigned char st_reg = 0;
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
st_reg = st_reg << 1;
gpio_out(structure->Scl, 1);
sht11_delay(structure);
if(gpio_in(structure->Sda))
st_reg |= 1;
gpio_out(structure->Scl, 0);
if(data_cnt == 7) {
gpio_function_set(structure->Sda, GPIO_OUT_OPEN_DRAIN);
gpio_out(structure->Sda, 0);
}
sht11_delay(structure);
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
gpio_function_set(structure->Sda, GPIO_IN_PULL_UP);
sht11_delay(structure);
*status_reg = st_reg;
/*
* Read checksum.
*/
unsigned char chk = 0;
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
chk = chk << 1;
gpio_out(structure->Scl, 1);
sht11_delay(structure);
if(gpio_in(structure->Sda))
chk |= 1;
gpio_out(structure->Scl, 0);
sht11_delay(structure);
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
structure->busy = false;
}
return true;
}
bool sht11_read(SHT11_t *structure) {
/*
* Check if sht11 is not responding.
* If sht11 will not respond until timeout will occurred,
* the busy flag will be set as false to permit to sht11_write function
* to send another command.
*/
if(timer_tick(&structure->Timeout_Timer)) {
structure->busy = false;
return false;
}
/*
* If busy flag is not busy this function will don't have anything to read from sh11.
*/
if(!structure->busy) return false;
/*
* If flag busy is true w will wait to read data.
* Now will wait the sda pin to be '0', that signify data ready to be read.
* If sda pin is '1' will return false, this signify that the sht11 is busy.
*/
if(gpio_in(structure->Sda)) return false;
/*
* Now the data is available on the buss.
* Will start to read data and return true, this is the single case that
* this function return true.
*/
unsigned char data_cnt;
sht11_delay(structure);
unsigned short data = 0;
/*
* Read MSB data
*/
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
data = data << 1;
gpio_out(structure->Scl, 1);
sht11_delay(structure);
if(gpio_in(structure->Sda))
data |= 1;
gpio_out(structure->Scl, 0);
if(data_cnt == 7) {
gpio_function_set(structure->Sda, GPIO_OUT_OPEN_DRAIN);
gpio_out(structure->Sda, 0);
}
sht11_delay(structure);
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
gpio_function_set(structure->Sda, GPIO_IN_PULL_UP);
sht11_delay(structure);
/*
* Read LSB data.
*/
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
data = data << 1;
gpio_out(structure->Scl, 1);
sht11_delay(structure);
if(gpio_in(structure->Sda))
data |= 1;
gpio_out(structure->Scl, 0);
if(data_cnt == 7) {
gpio_function_set(structure->Sda, GPIO_OUT_OPEN_DRAIN);
gpio_out(structure->Sda, 0);
}
sht11_delay(structure);
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
gpio_function_set(structure->Sda, GPIO_IN_PULL_UP);
sht11_delay(structure);
/*
* Read checksum.
*/
unsigned char chk = 0;
for(data_cnt = 0; data_cnt < 8; data_cnt++) {
chk = chk << 1;
gpio_out(structure->Scl, 1);
sht11_delay(structure);
if(gpio_in(structure->Sda))
chk |= 1;
gpio_out(structure->Scl, 0);
sht11_delay(structure);
}
gpio_out(structure->Scl, 1);
sht11_delay(structure);
gpio_out(structure->Scl, 0);
sht11_delay(structure);
structure->busy = false;
if(structure->reg_inst == SHT11_START_MEASURE_TEMPERATURE) {
structure->temperature = structure->vdd_comp + 0.01 * (float)data;
} else if(structure->reg_inst == SHT11_START_MEASURE_HUMIDITY) {
structure->humidity = -4 + 0.0405 * (float)data + -0.0000028 * ((float)data * (float)data);
}
return true;
}
