Y SI
library for SHT25 humidity and temperature sensor https://www.sensirion.com/products/humidity-sensor/
Revision 9:382955a266cb, committed 2021-10-06
- Comitter:
- YSI
- Date:
- Wed Oct 06 13:41:00 2021 +0000
- Parent:
- 8:bb3dbc86a180
- Child:
- 10:18e6cd816998
- Commit message:
- Add wait function compatible with mbed2.0, mbed5.0 and mbed6.0 and more.; Default wait for request is typical value and up to maximum value if necessary/
Changed in this revision
| lib_SHT25.cpp | Show annotated file Show diff for this revision Revisions of this file |
| lib_SHT25.h | Show annotated file Show diff for this revision Revisions of this file |
--- a/lib_SHT25.cpp Wed Sep 22 13:26:04 2021 +0000
+++ b/lib_SHT25.cpp Wed Oct 06 13:41:00 2021 +0000
@@ -9,22 +9,19 @@
* Example:
* @code
* #include "lib_SHT25.h"
-*
-* Serial pc(USBTX, USBRX);
+*
* SHT25 sensor(I2C_SDA, I2C_SCL);
*
* int main()
* {
-* float temperature, humidity;
* while(1)
* {
-* temperature = sensor.getTemperature();
-* humidity = sensor.getTemperature();
-* pc.printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
+* sensor.waitSafeHeat();
+* float temperature = sensor.getTemperature(), humidity = sensor.getHumidity();
+* printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
* sensor.waitSafeHeat();
* sensor.getData(&temperature, &humidity);
-* pc.printf("\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
-* sensor.waitSafeHeat();
+* printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
* }
* }
* @endcode
@@ -36,7 +33,7 @@
SHT25::SHT25(PinName sda, PinName scl, enum_sht_prec precision, int frequency) : _i2c(sda, scl)
{
- _i2c.frequency((frequency<=SHT_I2C_FREQUENCY)?frequency:SHT_I2C_FREQUENCY);
+ _i2c.frequency((frequency<=400e3)?frequency:400e3);
setPrecision(precision);
_temperature = _humidity = NAN;
_selfHeatTemperature = _selfHeatHumidity = false;
@@ -46,70 +43,72 @@
void SHT25::getData(float *tempC, float *relHumidity)
{
+ if(_selfHeatTemperature && _selfHeatHumidity) readData();
*tempC = _temperature;
*relHumidity = _humidity;
- if(_selfHeatTemperature && _selfHeatHumidity)
- readData(tempC, relHumidity);
}
-void SHT25::readData(float *tempC, float *relHumidity)
+void SHT25::readData(void)
{
- *tempC = _temperature = readTemperature();
- *relHumidity = _humidity = readHumidity();
+ _temperature = readTemperature();
+ _humidity = readHumidity();
}
float SHT25::getTemperature(void)
{
- if(_selfHeatTemperature)
- _temperature = readTemperature();
+ if(_selfHeatTemperature) _temperature = readTemperature();
return _temperature;
}
-float SHT25::readTemperature(void) // if I2C Freezing go down PullUp resistor to 1K or slow frequency
+float SHT25::readTemperature(void) // if I2C Freezing go down PullUp resistor to 2K or slow frequency
{
- char cmd[1] = {SHT_TRIG_TEMP_NHOLD}, rx[3] = {0xFF, 0xFF, 0xFF};
- if(!_i2c.write(SHT_I2C_ADDR_WRITE, cmd, 1, false))
+ char cmd[] = {SHT_TRIG_TEMP_NHOLD}, rx[] = {0xFF, 0xFF, 0xFF};
+ _selfHeatTemperature = false;
+ _t.attach(callback(this, &SHT25::keepSafeTemperature), SHT_SELF_HEATING);
+ if(!_i2c.write(SHT_I2C_ADDR, cmd, 1))
{
- wait_us(SHT_TEMP_MEASURE);
- _i2c.read(SHT_I2C_ADDR_READ, rx, 3, false);
- _selfHeatTemperature = false;
- _t.attach(callback(this, &SHT25::keepSafeTemperature), SHT_SELF_HEATING);
- return -46.85f + 175.72f * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0f);
+ SHT_WAIT(66);
+ int ack = _i2c.read(SHT_I2C_ADDR, rx, 3);
+ if(ack)
+ {
+ SHT_WAIT(19);
+ ack = _i2c.read(SHT_I2C_ADDR, rx, 3);
+ }
+ return ack?NAN:-46.85f + 175.72f * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0f);
}
return NAN;
}
float SHT25::getHumidity(void)
{
- if(_selfHeatHumidity)
- _humidity = readHumidity();
+ if(_selfHeatHumidity) _humidity = readHumidity();
return _humidity;
}
-float SHT25::readHumidity(void) // if I2C Freezing go down PullUp resistor to 1K or slow frequency
+float SHT25::readHumidity(void) // if I2C Freezing go down PullUp resistor to 2K or slow frequency
{
- char cmd[1] = {SHT_TRIG_RH_NHOLD}, rx[3] = {0xFF, 0xFF, 0xFF};
- if(!_i2c.write(SHT_I2C_ADDR_WRITE, cmd, 1, false))
+ char cmd[] = {SHT_TRIG_RH_NHOLD}, rx[] = {0xFF, 0xFF, 0xFF};
+ _selfHeatHumidity = false;
+ _h.attach(callback(this, &SHT25::keepSafeHumidity), SHT_SELF_HEATING);
+ if(!_i2c.write(SHT_I2C_ADDR, cmd, 1))
{
- wait_us(SHT_HUM_MEASURE);
- _i2c.read(SHT_I2C_ADDR_READ, rx, 3, false);
- _selfHeatHumidity = false;
- _h.attach(callback(this, &SHT25::keepSafeHumidity), SHT_SELF_HEATING);
- return -6.0f + 125.0f * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0f);
+ SHT_WAIT(29);
+ int ack = _i2c.read(SHT_I2C_ADDR, rx, 3);
+ return ack?NAN:-6.0f + 125.0f * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0f);
}
return NAN;
}
bool SHT25::setPrecision(const enum_sht_prec precision)
{
- char cmd[2] = {SHT_WRITE_REG_USER, precision};
- return !_i2c.write(SHT_I2C_ADDR_WRITE, cmd, 2, false);
+ char cmd[] = {SHT_WRITE_REG_USER, precision};
+ return !_i2c.write(SHT_I2C_ADDR, cmd, 2, false);
}
bool SHT25::softReset()
{
- char cmd[1] = {SHT_SOFT_RESET};
- return !_i2c.write(SHT_I2C_ADDR_WRITE, cmd, 1, false);
+ char cmd[] = {SHT_SOFT_RESET};
+ return !_i2c.write(SHT_I2C_ADDR, cmd, 1, false);
}
void SHT25::waitSafeHeat(void)
--- a/lib_SHT25.h Wed Sep 22 13:26:04 2021 +0000
+++ b/lib_SHT25.h Wed Oct 06 13:41:00 2021 +0000
@@ -9,22 +9,19 @@
* Example:
* @code
* #include "lib_SHT25.h"
-*
-* Serial pc(USBTX, USBRX);
+*
* SHT25 sensor(I2C_SDA, I2C_SCL);
*
* int main()
* {
-* float temperature, humidity;
* while(1)
* {
-* temperature = sensor.getTemperature();
-* humidity = sensor.getTemperature();
-* pc.printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
+* sensor.waitSafeHeat();
+* float temperature = sensor.getTemperature(), humidity = sensor.getHumidity();
+* printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
* sensor.waitSafeHeat();
* sensor.getData(&temperature, &humidity);
-* pc.printf("\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
-* sensor.waitSafeHeat();
+* printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
* }
* }
* @endcode
@@ -37,9 +34,8 @@
#include "mbed.h"
-#define SHT_I2C_FREQUENCY 400e3 //Sensor I2C Frequency max 400KHz
-#define SHT_I2C_ADDR_WRITE 0x80 //Sensor I2C address write
-#define SHT_I2C_ADDR_READ 0x81 //Sensor I2C address read
+#define SHT_I2C_FREQUENCY 100e3 //Sensor I2C Frequency max 400KHz
+#define SHT_I2C_ADDR 0x80 //Sensor I2C address
#define SHT_TRIG_TEMP_HOLD 0xE3 //Trigger Temp with hold master
#define SHT_TRIG_RH_HOLD 0xE5 //Trigger RH with hold master
#define SHT_TRIG_TEMP_NHOLD 0xF3 //Trigger Temp with no hold master
@@ -47,12 +43,12 @@
#define SHT_WRITE_REG_USER 0xE6 //Write to user register
#define SHT_READ_REG_USER 0xE7 //Read from user register
#define SHT_SOFT_RESET 0xFE //Soft reset the sensor
-#define SHT_TEMP_MEASURE 85e3 //Waiting to measure T on 14bit
-#define SHT_HUM_MEASURE 29e3 //Waiting to measure H on 12bit
#if MBED_MAJOR_VERSION > 5
-#define SHT_SELF_HEATING 1s //Keep self heating
+#define SHT_SELF_HEATING 2s //Keep self heating
+#define SHT_WAIT(ms) (thread_sleep_for(ms))
#else
#define SHT_SELF_HEATING 0x01 //Keep self heating
+#define SHT_WAIT(ms) (wait_us(1000*ms))
#endif
@@ -71,7 +67,7 @@
* @param sda I2C pin
* @param scl I2C pin
* @param precision SHT25 precision for humidity(default 12 bits) and temperature(default 14 bits)
- * @param frequency I2C frequency, default and maximum 400KHz
+ * @param frequency I2C frequency, default 100KHz and maximum 400KHz
*/
SHT25(PinName sda, PinName scl, enum_sht_prec precision = SHT_PREC_RH12T14, int frequency = SHT_I2C_FREQUENCY);
@@ -121,14 +117,13 @@
I2C _i2c;
Timeout _t, _h;
private:
- void readData(float *, float *);
+ void readData(void);
float readTemperature(void);
float readHumidity(void);
void keepSafeTemperature(void);
void keepSafeHumidity(void);
float _temperature, _humidity;
bool _selfHeatTemperature, _selfHeatHumidity;
- char _rxT[3];
};
#endif
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