Tasmota/tasmota/xsns_26_lm75ad.ino

/*
  xsns_26_lm75ad.ino - Support for I2C LM75AD Temperature Sensor

  Copyright (C) 2021  Andre Thomas and Theo Arends

  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_I2C
#ifdef USE_LM75AD

/*********************************************************************************************\
 * LM75AD - Temperature
 *
 * Docs at https://www.nxp.com/docs/en/data-sheet/LM75A.pdf
 *
 * I2C Address: 0x48 - 0x4F
\*********************************************************************************************/

#define XSNS_26                 26
#define XI2C_20                 20  // See I2CDEVICES.md

#define LM75AD_ADDRESS1					0x48
#define LM75AD_ADDRESS2					0x49
#define LM75AD_ADDRESS3					0x4A
#define LM75AD_ADDRESS4					0x4B
#define LM75AD_ADDRESS5					0x4C
#define LM75AD_ADDRESS6					0x4D
#define LM75AD_ADDRESS7					0x4E
#define LM75AD_ADDRESS8					0x4F

#define LM75_TEMP_REGISTER      0x00
#define LM75_CONF_REGISTER      0x01
#define LM75_THYST_REGISTER     0x02
#define LM75_TOS_REGISTER       0x03

bool lm75ad_type = false;
uint8_t lm75ad_address;
uint8_t lm75ad_addresses[] = { LM75AD_ADDRESS1, LM75AD_ADDRESS2, LM75AD_ADDRESS3, LM75AD_ADDRESS4, LM75AD_ADDRESS5, LM75AD_ADDRESS6, LM75AD_ADDRESS7, LM75AD_ADDRESS8 };

void LM75ADDetect(void)
{
  for (uint32_t i = 0; i < sizeof(lm75ad_addresses); i++) {
    lm75ad_address = lm75ad_addresses[i];
    if (I2cActive(lm75ad_address)) {
      continue; }
    if (!I2cSetDevice(lm75ad_address)) {
      continue; // do not make the next step without a confirmed device on the bus
    }
    uint16_t buffer;
    if (I2cValidRead16(&buffer, lm75ad_address, LM75_THYST_REGISTER)) {
      if (buffer == 0x4B00) {
        lm75ad_type = true;
        I2cSetActiveFound(lm75ad_address, "LM75AD");
        break;
      }
    }
  }
}

float LM75ADGetTemp(void)
{
  int16_t sign = 1;

  uint16_t t = I2cRead16(lm75ad_address, LM75_TEMP_REGISTER);
  if (t & 0x8000) { // we are getting a negative temperature value
    t = (~t) +0x20;
    sign = -1;
  }
  t = t >> 5; // shift value into place (5 LSB not used)
  return ConvertTemp(sign * t * 0.125);
}

void LM75ADShow(bool json)
{
  float t = LM75ADGetTemp();

  if (json) {
    ResponseAppend_P(JSON_SNS_F_TEMP, "LM75AD", Settings.flag2.temperature_resolution, &t);
#ifdef USE_DOMOTICZ
    if (0 == TasmotaGlobal.tele_period) DomoticzFloatSensor(DZ_TEMP, t);
#endif  // USE_DOMOTICZ
#ifdef USE_WEBSERVER
  } else {
    WSContentSend_Temp("LM75AD", t);
#endif  // USE_WEBSERVER
  }
}

/*********************************************************************************************\
 * Interface
\*********************************************************************************************/

bool Xsns26(uint8_t function)
{
  if (!I2cEnabled(XI2C_20)) { return false; }

  bool result = false;

  if (FUNC_INIT == function) {
    LM75ADDetect();
  }
  else if (lm75ad_type) {
    switch (function) {
      case FUNC_JSON_APPEND:
        LM75ADShow(1);
        break;
  #ifdef USE_WEBSERVER
      case FUNC_WEB_SENSOR:
        LM75ADShow(0);
        break;
  #endif  // USE_WEBSERVER
    }
  }
  return result;
}

#endif  // USE_LM75AD
#endif  // USE_I2C