Tasmota/sonoff/xsns_22_sr04.ino

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/*
xsns_22_sr04.ino - SR04 ultrasonic sensor support for Sonoff-Tasmota
Copyright (C) 2018 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 max(a,b) ((a)>(b)?(a):(b))
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#define min(a,b) ((a)<(b)?(a):(b))
uint8_t sr04_echo_pin = 0;
uint8_t sr04_trig_pin = 0;
/*********************************************************************************************\
* Embedded stripped and tuned NewPing library from Tim Eckel - teckel@leethost.com
* https://bitbucket.org/teckel12/arduino-new-ping
\*********************************************************************************************/
#define US_ROUNDTRIP_CM 58 // Microseconds (uS) it takes sound to travel round-trip 1cm (2cm total), uses integer to save compiled code space. Default: 58
#define US_ROUNDTRIP_IN 148 // Microseconds (uS) it takes sound to travel round-trip 1 inch (2 inches total), uses integer to save compiled code space. Default: 148
#define PING_MEDIAN_DELAY 29000
#define MAX_SENSOR_DISTANCE 500
#define PING_OVERHEAD 5
// Conversion from uS to distance (round result to nearest cm or inch).
#define EchoConvert(echoTime, conversionFactor) (max(((unsigned int)echoTime + conversionFactor / 2) / conversionFactor, (echoTime ? 1 : 0)))
/********************************************************************************************/
void Sr04Init()
{
sr04_echo_pin = pin[GPIO_SR04_ECHO];
sr04_trig_pin = pin[GPIO_SR04_TRIG];
pinMode(sr04_trig_pin, OUTPUT);
pinMode(sr04_echo_pin, INPUT_PULLUP);
}
boolean Sr04Read(uint16_t *distance)
{
uint16_t duration = 0;
*distance = 0;
/* Send ping and get delay */
duration = Sr04GetSamples(9, 250);
/* Calculate the distance (in cm) based on the speed of sound. */
*distance = EchoConvert(duration, US_ROUNDTRIP_CM);
return 1;
}
uint16_t Sr04Ping(uint16_t max_cm_distance)
{
uint16_t duration = 0;
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uint16_t maxEchoTime;
maxEchoTime = min(max_cm_distance + 1, (uint16_t) MAX_SENSOR_DISTANCE + 1) * US_ROUNDTRIP_CM;
/* The following trigPin/echoPin cycle is used to determine the
distance of the nearest object by bouncing soundwaves off of it. */
digitalWrite(sr04_trig_pin, LOW);
delayMicroseconds(2);
digitalWrite(sr04_trig_pin, HIGH);
delayMicroseconds(10);
digitalWrite(sr04_trig_pin, LOW);
/* Wait for the echo */
duration = pulseIn(sr04_echo_pin, HIGH, 26000) - PING_OVERHEAD;
return (duration > maxEchoTime) ? 0 : duration;
}
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uint16_t Sr04GetSamples(uint8_t it, uint16_t max_cm_distance)
{
uint16_t uS[it];
uint16_t last;
uint8_t j;
uint8_t i = 0;
uint16_t t;
uS[0] = 0;
while (i < it) {
t = micros();
last = Sr04Ping(max_cm_distance);
if (last != 0) {
if (i > 0) {
for (j = i; j > 0 && uS[j - 1] < last; j--) {
uS[j] = uS[j - 1];
}
} else {
j = 0;
}
uS[j] = last;
i++;
} else {
it--;
}
if (i < it && micros() - t < PING_MEDIAN_DELAY) {
delay((PING_MEDIAN_DELAY + t - micros()) / 1000);
}
}
return (uS[1]); // Return the ping distance from the 2nd highest reading
}
#ifdef USE_WEBSERVER
const char HTTP_SNS_DISTANCE[] PROGMEM =
"%s{s}SR04 " D_DISTANCE "{m}%d" D_UNIT_CENTIMETER "{e}"; // {s} = <tr><th>, {m} = </th><td>, {e} = </td></tr>
#endif // USE_WEBSERVER
void Sr04Show(boolean json)
{
uint16_t distance;
if (Sr04Read(&distance)) { // Check if read failed
if(json) {
snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"SR04\":{\"" D_JSON_DISTANCE "\":%d}"), mqtt_data, distance);
#ifdef USE_WEBSERVER
} else {
snprintf_P(mqtt_data, sizeof(mqtt_data), HTTP_SNS_DISTANCE, mqtt_data, distance);
#endif // USE_WEBSERVER
}
}
}
/*********************************************************************************************\
* Interface
\*********************************************************************************************/
#define XSNS_22
boolean Xsns22(byte function)
{
boolean result = false;
if ((pin[GPIO_SR04_ECHO] < 99) && (pin[GPIO_SR04_TRIG] < 99)) {
switch (function) {
case FUNC_INIT:
Sr04Init();
break;
case FUNC_JSON_APPEND:
Sr04Show(1);
break;
#ifdef USE_WEBSERVER
case FUNC_WEB_APPEND:
Sr04Show(0);
break;
#endif // USE_WEBSERVER
}
}
return result;
}
#endif // USE_SR04