Tasmota/tasmota/xsns_74_lmt01.ino

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/*
xns_74_lmt01.ino - Support for single wire LMT01 Temperature Sensor
Copyright (C) 2020 Theo Arends, Justifiably
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef USE_LMT01
/*********************************************************************************************\
* LMT01 - 0.5°C Accurate 2-Pin Digital Output Temperature Sensor With Pulse Count Interface
*
* Uses fragments of public domain code LMT01_Example.ino released by Texas Instruments, July 10th 2017.
* See https://training.ti.com/how-interface-lmt01-temperature-sensor-arduino
\*********************************************************************************************/
#define XSNS_74 74
#define LMT01_TIMEOUT 200 // ms timeout for a reading cycle
bool lmt01_initialized = false;
float lmt01_temperature = NAN;
void LMT01_Init(void) {
if (PinUsed(GPIO_LMT01)) {
pinMode(Pin(GPIO_LMT01), INPUT);
attachInterrupt(Pin(GPIO_LMT01), LMT01_countPulse, FALLING);
lmt01_initialized = true;
}
}
volatile int lmt01_pulseCount = 0;
void ICACHE_RAM_ATTR LMT01_countPulse(void) {
lmt01_pulseCount++;
}
void LMT01_GetTemperature(void) {
int pulses = 0;
pulses = LMT01_getPulses();
if (pulses >= 0) {
// simple linear conversion, datasheet has a look-up table alternative
// which is accurate over a wider temperature range
lmt01_temperature = ConvertTemp(0.0625 * pulses - 50);
} else {
lmt01_temperature = NAN; // Timeout
}
}
int LMT01_getPulses(void) {
int timeout = LMT01_TIMEOUT;
int hold = -1;
// complete current pulse cycle (50ms max)
while(lmt01_pulseCount != hold && --timeout > 0) {
hold = lmt01_pulseCount;
delay(1);
}
lmt01_pulseCount = 0;
// wait for start of next (54ms max)
while(lmt01_pulseCount == 0 && --timeout > 0) {
delay(1);
}
hold = -1;
// take this count (up to 50ms)
while(lmt01_pulseCount != hold && --timeout > 0) {
hold = lmt01_pulseCount;
delay(1);
}
// discard spurious low counts
if (timeout > 0 && hold >= 10) {
return hold;
}
return -1;
}
void LMT01_Show(bool Json) {
char temp[33];
dtostrfd(lmt01_temperature, Settings.flag2.temperature_resolution, temp);
if (Json) {
ResponseAppend_P(JSON_SNS_TEMP, "LMT01", temp);
#ifdef USE_DOMOTICZ
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if (0 == TasmotaGlobal.tele_period) {
DomoticzSensor(DZ_TEMP, temp);
}
#endif // USE_DOMOTICZ
#ifdef USE_KNX
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if (0 == TasmotaGlobal.tele_period) {
KnxSensor(KNX_TEMPERATURE, lmt01_temperature);
}
#endif // USE_KNX
#ifdef USE_WEBSERVER
} else {
WSContentSend_PD(HTTP_SNS_TEMP, "LMT01", temp, TempUnit());
#endif // USE_WEBSERVER
}
}
/*********************************************************************************************\
* Interface
\*********************************************************************************************/
bool Xsns74(uint8_t function)
{
bool result = false;
if (FUNC_INIT == function) {
LMT01_Init();
}
else if (lmt01_initialized) {
switch (function) {
case FUNC_EVERY_SECOND:
LMT01_GetTemperature();
break;
case FUNC_JSON_APPEND:
LMT01_Show(true);
break;
#ifdef USE_WEBSERVER
case FUNC_WEB_SENSOR:
LMT01_Show(false);
break;
#endif // USE_WEBSERVER
}
}
return result;
}
#endif // USE_LMT01