Tasmota/tasmota/xsns_88_am2320.ino

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/*
xsns_88_am2320.ino - Tasmota driver for I2C AM2320 Temp/Hum Sensor
Copyright (C) 2019 Lars Wessels
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_AM2320
/*********************************************************************************************\
* AM2320 - Digital Temperature and Humidity Sensor
* https://akizukidenshi.com/download/ds/aosong/AM2320.pdf
*
* based on https://github.com/hibikiledo/AM2320 from Ratthanan Nalintasnai
* and https://github.com/adafruit/Adafruit_AM2320 from Limor Fried (Adafruit Industries)
* and https://github.com/nightphobos/tasmota-am2320-i2c-driver as adaptation code to Tamota
\*********************************************************************************************/
#define XSNS_92 92
#define XI2C_92 92 // See I2CDEVICES.md
#define AM2320_ADDR 0x5C // use 7bit address: 0xB8 >> 1
#define INIT_MAX_RETRIES 5
char AM2320_types[] = "AM2320";
uint8_t am2320_found = 0;
struct AM2320_Readings {
uint8_t valid = 0;
float t = NAN;
float h = NAN;
} AM2320;
bool Am2320Init(void)
{
// wake AM2320 up, goes to sleep to not warm up and affect the humidity sensor
Wire.beginTransmission(AM2320_ADDR);
Wire.write(0x02);
Wire.endTransmission();
delay(1);
Wire.beginTransmission(AM2320_ADDR); // start transmission
Wire.write(0x03); // read register data (function code)
Wire.write(0x00); // start address (0x00 = Temp, 0x02 = Humidity)
Wire.write(0x04); // read 4 bytes (2 byte temperature + 2 byte humidity)
if (Wire.endTransmission(1) != 0) {
return false;
}
return true;
}
unsigned int crc16(byte *ptr, byte length)
{
unsigned int crc = 0xFFFF;
while(length--) {
crc ^= *ptr++;
for(uint8_t i = 0; i < 8; i++) {
if ((crc & 0x01) != 0) {
crc >>= 1;
crc ^= 0xA001;
} else {
crc >>= 1;
}
}
}
return crc;
}
bool Am2320Read(void)
{
byte buf[8];
if (AM2320.valid > 0) { AM2320.valid--; }
if (!Am2320Init()) { return false; }
delayMicroseconds(1600); // >=1.5ms
Wire.requestFrom(AM2320_ADDR, 8); // request all data
if (Wire.available() != 8) { return false; }
// read 8 bytes: preamble(2) + data(2) + crc(2)
memset(buf, 0, 8);
for (uint8_t i = 0; i < 8; i++) {
buf[i] = Wire.read();
}
if (buf[0] != 0x03) { return false; } // must be 0x03 function code reply
if (buf[1] != 4) { return false; } // must be 4 bytes reply
// verify checksum
unsigned int receivedCrc = (buf[7] << 8) | buf[6]; // pack high and low byte together
if (receivedCrc == crc16(buf, 6)) { // preamble + data
int temperature = ((buf[4] & 0x7F) << 8) | buf[5];
AM2320.t = temperature / 10.0;
// check for negative temp reading
AM2320.t = ((buf[4] & 0x80) >> 7) == 1 ? AM2320.t * (-1) : AM2320.t;
int humidity = (buf[2] << 8) | buf[3];
AM2320.h = humidity / 10.0;
AM2320.valid = SENSOR_MAX_MISS; // reset error counter
return true;
} else {
AddLog(LOG_LEVEL_ERROR, PSTR(D_LOG_I2C "Am2320Read() checksum failed"));
return false;
}
}
void Am2320Detect(void)
{
if (Am2320Init()) {
if (!am2320_found) {
AddLog(LOG_LEVEL_INFO, S_LOG_I2C_FOUND_AT, AM2320_types, AM2320_ADDR);
} else {
AddLog(LOG_LEVEL_DEBUG, S_LOG_I2C_FOUND_AT, AM2320_types, AM2320_ADDR);
}
am2320_found = 3;
} else {
if (am2320_found) { am2320_found--; }
}
}
void Am2320EverySecond(void)
{
// if (!(uptime%10)) {
// Am2320Detect(); // look for sensor every 10 seconds, after three misses it's set to not found
// } else if (uptime & 1 && am2320_found) { // read from sensor every 2 seconds
if (TasmotaGlobal.uptime &1) {
if (!Am2320Read()) {
AddLogMissed(AM2320_types, AM2320.valid);
}
// }
}
}
void Am2320Show(bool json)
{
if (!am2320_found) { return; } // no sensor, no show :(
float t, h, dewpoint;
if (AM2320.valid) {
t = ConvertTemp(AM2320.t);
h = ConvertHumidity(AM2320.h);
dewpoint = CalcTempHumToDew(AM2320.t, AM2320.h);
} else {
t = -1;
h = -1;
dewpoint = -1;
}
if (json) {
ResponseAppend_P(PSTR(",\"%s\":{\"" D_JSON_TEMPERATURE "\":%f,\"" D_JSON_HUMIDITY "\":%f,\"" D_JSON_DEWPOINT "\":%f}"),AM2320_types,t,h,dewpoint);
#ifdef USE_DOMOTICZ
if (0 == Settings->tele_period) {
DomoticzTempHumPressureSensor(t, h);
}
#endif // USE_DOMOTICZ
#ifdef USE_KNX
if (0 == Settings->tele_period) {
KnxSensor(KNX_TEMPERATURE, t);
KnxSensor(KNX_HUMIDITY, h);
}
#endif // USE_KNX
#ifdef USE_WEBSERVER
} else {
WSContentSend_THD(AM2320_types, t, h);
#endif // USE_WEBSERVER
}
}
/*********************************************************************************************\
* Interface
\*********************************************************************************************/
bool Xsns92(uint8_t function)
{
if (!I2cEnabled(XI2C_92)) { return false; }
boolean result = false;
if (FUNC_INIT == function) {
Am2320Detect();
}
else if (am2320_found) {
switch (function) {
case FUNC_EVERY_SECOND:
Am2320EverySecond();
break;
case FUNC_JSON_APPEND:
Am2320Show(1);
break;
#ifdef USE_WEBSERVER
case FUNC_WEB_SENSOR:
Am2320Show(0);
break;
#endif // USE_WEBSERVER
}
}
return result;
}
#endif // USE_AM2320
#endif // USE_I2C