don't reset the sensor in the begin() func

Author: dizcza

README.md

@@ -12,13 +12,17 @@ See [sdpsensor-esp-arduino.ino](./sdpsensor-esp-arduino.ino).
 Serial output:
 
 ```
-[  1021][I][sdpsensor.cpp:86] initI2C(): I2C0 line initialized
-[  1021][I][sdpsensor.cpp:204] reset(): SDPSensor::reset ESP_OK
-[  1042][I][sdpsensor.cpp:157] begin(): Initialized SDP31 500Pa sensor (PID=0x03010188)
-[  1133][I][sdpsensor.cpp:169] begin(): SDP31 pressure scale: 60
-[  1133][I][sdpsensor.cpp:182] startContinuous(): SDPSensor::startContinuous ESP_OK
+[  1021][I][sdpsensor.cpp:95] initI2C(): I2C0 line initialized
+[  1021][I][sdpsensor.cpp:232] stopContinuous(): SDPSensor::stopContinuous ESP_OK
+[  1043][I][sdpsensor.cpp:182] begin(): Initialized SDP31 500Pa sensor (PID=0x03010188)
+[  1134][I][sdpsensor.cpp:200] begin(): SDP31 pressure scale: 60
+[  1134][I][sdpsensor.cpp:219] startContinuous(): SDPSensor::startContinuous ESP_OK
 
 [  2154][I][sdpsensor-esp-arduino.ino:32] loop(): raw pressure: 0, err code: ESP_OK
 ...
 ```
 
+### Resetting the sensor
+
+If the sensor was working in a continuous mode, prior to executing any I2C commands, it ought to be reset by calling either the `stopContinuous()` or `reset()` function. Note, however, that the `reset` commands are received by *all* I2C peripherals connected to the same I2C line (port), because it employs the `0x00` address, which is the I2C general call address.
+

sdpsensor-esp-arduino.ino

@@ -20,6 +20,7 @@ void setup() {
   Serial.begin(115200);
   delay(1000); // let serial console settle
   sdp.initI2C(19, 23);  // same as Wire.begin(19, 23)
+  sdp.stopContinuous();  // sdp.reset() is also possible
   sdp.begin();
   sdp.startContinuous();
 }

sdpsensor.cpp

@@ -106,8 +106,6 @@ void logInitFailed(esp_err_t err) {
 
 
 esp_err_t SDPSensor::begin() {
-	SDPSensor::reset();  // stop continuous mode
-
 	// commands to read product id
 	uint8_t cmd0[SDPSENSOR_I2C_CMD_LEN] = { 0x36, 0x7C };
 	uint8_t cmd1[SDPSENSOR_I2C_CMD_LEN] = { 0xE1, 0x02 };
@@ -213,8 +211,6 @@ uint16_t SDPSensor::getPressureScale() {
 
 
 esp_err_t SDPSensor::startContinuous() {
-    if (!initialized) return ESP_ERR_INVALID_STATE;
-
 	uint8_t cmd[SDPSENSOR_I2C_CMD_LEN] = { 0x36, 0x1E };
 	const TickType_t ticks_to_wait_long = pdMS_TO_TICKS(100);
 	esp_err_t err = i2c_master_write_to_device(i2c_port, i2c_addr, cmd,
@@ -228,8 +224,6 @@ esp_err_t SDPSensor::startContinuous() {
 
 
 esp_err_t SDPSensor::stopContinuous() {
-    if (!initialized) return ESP_ERR_INVALID_STATE;
-	
     uint8_t cmd[SDPSENSOR_I2C_CMD_LEN] = { 0x3F, 0xF9 };
 	const TickType_t ticks_to_wait_long = pdMS_TO_TICKS(100);
 	esp_err_t err = i2c_master_write_to_device(i2c_port, i2c_addr, cmd,

sdpsensor.h

@@ -46,10 +46,12 @@ class SDPSensor {
         /**
          * Initialize an SDP sensor.
          *
-         * Firstly, it resets the sensor prior to executing any I2C commands.
-         * Then it reads and saves the sensor serial number and diff pressure scale.
-         * The returned error code other than ESP_OK (0) means that the sensor has
-         * not been properly initialized.
+         * You may need to call `stopContinuous()` or `reset()` function
+         * prior to initializing the sensor, if previously it was working in
+         * a continuous mode.
+         * The product ID and the diff pressure scale are read and saved here.
+         * The returned error code other than ESP_OK (0) means that the sensor
+         * has not been properly initialized.
          *
          * @returns the error code (defined in esp_err.h)
          */