Tasmota/tasmota/xsns_22_sr04.ino

/*
  xsns_22_sr04.ino - SR04 ultrasonic sensor support for Tasmota

  Copyright (C) 2021  Nuno Ferreira 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_SR04
/*********************************************************************************************\
 * HC-SR04, HC-SR04+, JSN-SR04T - Ultrasonic distance sensor
 *
 * Code for SR04 family of ultrasonic distance sensors
 * References:
 * - https://www.dfrobot.com/wiki/index.php/Weather-proof_Ultrasonic_Sensor_SKU_:_SEN0207
\*********************************************************************************************/

#define XSNS_22                   22

#ifndef SR04_MAX_SENSOR_DISTANCE
#define SR04_MAX_SENSOR_DISTANCE  500
#endif

#include <NewPing.h>
#include <TasmotaSerial.h>

struct {
  uint8_t type;
  real64_t distance;
} SR04;

NewPing* sonar = nullptr;
TasmotaSerial* sonar_serial = nullptr;

uint16_t Sr04TMiddleValue(uint16_t first, uint16_t second, uint16_t third) {
  uint16_t ret = first;
  if (first > second) {
    first = second;
    second = ret;
  }

  if (third < first) {
    return first;
  } else if (third > second) {
    return second;
  } else {
    return third;
  }
}

uint16_t Sr04TMode2Distance(void) {
  sonar_serial->setTimeout(300);
  const char startByte = 0xff;

  if (!sonar_serial->find(startByte)) {
      //DEBUG_SENSOR_LOG(PSTR("SR4: No start byte"));
      return NO_ECHO;
  }

  delay(5);

  uint8_t crc = sonar_serial->read();
  //read high byte
  uint16_t distance = ((uint16_t)crc) << 8;

  //read low byte
  distance += sonar_serial->read();
  crc += distance & 0x00ff;
  crc += 0x00FF;

  //check crc sum
  if (crc != sonar_serial->read()) {
    AddLog(LOG_LEVEL_ERROR,PSTR("SR4: Reading CRC error."));
    return NO_ECHO;
  }
  //DEBUG_SENSOR_LOG(PSTR("SR4: Distance: %d"), distance);
  return distance;
}

uint16_t Sr04TMode3Distance() {
  sonar_serial->write(0x55);
  sonar_serial->flush();

  return Sr04TMode2Distance();
}

void Sr04TReading(void) {
  switch (SR04.type) {
    case 3:
      SR04.distance = (real64_t)(Sr04TMiddleValue(Sr04TMode3Distance(), Sr04TMode3Distance(), Sr04TMode3Distance())) / 10; //convert to cm
      break;
    case 2:
      //empty input buffer first
      while(sonar_serial->available()) sonar_serial->read();
      SR04.distance = (real64_t)(Sr04TMiddleValue(Sr04TMode2Distance(), Sr04TMode2Distance(), Sr04TMode2Distance())) / 10;
      break;
    case 1:
      SR04.distance = (real64_t)(sonar->ping_median(5))/ US_ROUNDTRIP_CM;
      break;
    default:
      SR04.distance = NO_ECHO;
  }

  return;
}

/*********************************************************************************************/

void Sr04TModeDetect(void) {
  if (!PinUsed(GPIO_SR04_ECHO)) { return; }

  int sr04_echo_pin = Pin(GPIO_SR04_ECHO);
  int sr04_trig_pin = (PinUsed(GPIO_SR04_TRIG)) ? Pin(GPIO_SR04_TRIG) : Pin(GPIO_SR04_ECHO);   // if GPIO_SR04_TRIG is not configured use single PIN mode with GPIO_SR04_ECHO only
  sonar_serial = new TasmotaSerial(sr04_echo_pin, sr04_trig_pin, 1);

  if (sonar_serial->begin(9600)) {
    DEBUG_SENSOR_LOG(PSTR("SR4: Detect mode"));

    if (PinUsed(GPIO_SR04_TRIG)) {
      SR04.type = (Sr04TMiddleValue(Sr04TMode3Distance(), Sr04TMode3Distance(), Sr04TMode3Distance()) != NO_ECHO) ? 3 : 1;
    } else {
      SR04.type = 2;
    }
  } else {
    SR04.type = 1;
  }

  if (SR04.type < 2) {
    delete sonar_serial;
    sonar_serial = nullptr;
    if (! PinUsed(GPIO_SR04_TRIG)) {
      sr04_trig_pin = Pin(GPIO_SR04_ECHO);  // if GPIO_SR04_TRIG is not configured use single PIN mode with GPIO_SR04_ECHO only
    }
    sonar = new NewPing(sr04_trig_pin, sr04_echo_pin, SR04_MAX_SENSOR_DISTANCE);
  } else {
    if (sonar_serial->hardwareSerial()) {
      ClaimSerial();
    }
  }

  AddLog(LOG_LEVEL_INFO,PSTR("SR4: Mode %d"), SR04.type);
}

void Sr04Show(bool json) {
  if (SR04.distance != 0) {                // Check if read failed
    char distance_chr[33];
    dtostrfd(SR04.distance, 3, distance_chr);

    if(json) {
      ResponseAppend_P(PSTR(",\"SR04\":{\"" D_JSON_DISTANCE "\":%s}"), distance_chr);
#ifdef USE_DOMOTICZ
      if (0 == TasmotaGlobal.tele_period) {
        DomoticzSensor(DZ_COUNT, distance_chr);  // Send distance as Domoticz Counter value
      }
#endif  // USE_DOMOTICZ
#ifdef USE_WEBSERVER
    } else {
      WSContentSend_PD(HTTP_SNS_DISTANCE_CM, "SR04", distance_chr);
#endif  // USE_WEBSERVER
    }
  }
}

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

bool Xsns22(uint8_t function) {
  bool result = false;

  if (FUNC_INIT == function) {
    Sr04TModeDetect();
  }
  else if (SR04.type) {
    switch (function) {
      case FUNC_EVERY_SECOND:
        Sr04TReading();
        result = true;
        break;
      case FUNC_JSON_APPEND:
        Sr04Show(1);
        break;
#ifdef USE_WEBSERVER
      case FUNC_WEB_SENSOR:
        Sr04Show(0);
        break;
#endif  // USE_WEBSERVER
    }
  }
  return result;
}

#endif  // USE_SR04