Canberk Sönmez
/
SHT21
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Revision 1:f4a1942b4486, committed 2017-09-13
- Comitter:
- odtulumbedder
- Date:
- Wed Sep 13 13:36:04 2017 +0000
- Parent:
- 0:062188c0bb61
- Commit message:
- file order fixed.
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/SHT21.cpp Wed Sep 13 13:36:04 2017 +0000
@@ -0,0 +1,102 @@
+#include "SHT21.hpp"
+
+const uint16_t SHT21::POLYNOMIAL = 0x131;
+
+SHT21::SHT21(PinName sda, PinName scl, char addr) :
+ addr_(addr),
+ pi2c_(new I2C(sda, scl)),
+ i2c_(*pi2c_) {
+}
+
+SHT21::SHT21(I2C &i2c, char addr) :
+ addr_(addr),
+ pi2c_(NULL),
+ i2c_(i2c) {
+}
+
+float SHT21::temperature() {
+ uint16_t r = readRaw(TRIGGER_T_MEASUREMENT_HM);
+ r &= ~0x0003;
+ return (-46.85 + 175.72/65536 * (float) r);
+}
+
+float SHT21::humidity() {
+ uint16_t r = readRaw(TRIGGER_RH_MEASUREMENT_HM);
+ r &= ~0x0003;
+ return (-6.0 + 125.0/65536 * (float) r);
+}
+
+void SHT21::reset() {
+ uint8_t pcmd [] = { SOFT_RESET };
+ i2c_.write(addr_, (const char *) pcmd, 1);
+ wait_ms(15);
+}
+
+void SHT21::serialNumber(uint8_t *serialNumber) {
+ uint8_t data[8];
+ uint8_t pcmd0[2] = { 0xFA, 0x0F };
+ uint8_t pcmd1[2] = { 0xFC, 0xC9 };
+ uint8_t i = 0;
+ i2c_.write(addr_, (const char *) pcmd0, 2);
+ i2c_.read(addr_, (char *) data, 8);
+
+ serialNumber[5] = data[i++];
+ i++;
+ serialNumber[4] = data[i++];
+ i++;
+ serialNumber[3] = data[i++];
+ i++;
+ serialNumber[2] = data[i++];
+ i = 0;
+
+ i2c_.write(addr_, (const char *) pcmd1, 2);
+ i2c_.read(addr_, (char *) data, 6);
+
+ serialNumber[1] = data[i++];
+ serialNumber[0] = data[i++];
+ i++;
+ serialNumber[7] = data[i++];
+ serialNumber[8] = data[i++];
+ i = 0;
+}
+
+SHT21::~SHT21() {
+ if (pi2c_) delete pi2c_;
+}
+
+uint16_t SHT21::readRaw(uint8_t cmd) {
+ uint8_t checksum;
+ uint8_t data[2];
+ uint16_t result;
+
+ uint8_t pcmd [] = { cmd };
+
+ i2c_.write(addr_, (const char *) pcmd, 1);
+ i2c_.read(addr_, (char *) data, 2);
+ i2c_.read(addr_, (char *) &checksum, 1);
+
+ result = data[0] << 8;
+ result += data[1];
+
+ if (crcChecksum(data, 2, checksum)) {
+ reset();
+ return 1;
+ }
+ return result;
+}
+
+bool SHT21::crcChecksum(const uint8_t *data, uint8_t sz, uint8_t checksum) {
+ uint8_t crc = 0;
+
+ for (uint8_t i = 0; i < sz; ++i) {
+ crc ^= data[i];
+ for (uint8_t j /* bit index */ = 8; j > 0; --j) {
+ if (crc & 0x80)
+ crc = (crc << 1) ^ POLYNOMIAL;
+ else
+ crc = (crc << 1);
+ }
+ }
+
+ return crc == checksum;
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/SHT21.hpp Wed Sep 13 13:36:04 2017 +0000
@@ -0,0 +1,39 @@
+#ifndef SHT21_HPP_INCLUDED
+#define SHT21_HPP_INCLUDED
+
+#include "mbed.h"
+
+class SHT21 {
+public:
+ SHT21(PinName sda, PinName scl, char addr = (0x40 << 1));
+ SHT21(I2C &i2c, char addr = (0x40 << 1));
+
+ float temperature();
+ float humidity();
+
+ void reset();
+ void serialNumber(uint8_t *serialNumber);
+
+ ~SHT21();
+private:
+ enum commands {
+ TRIGGER_T_MEASUREMENT_HM = 0xE3,
+ TRIGGER_RH_MEASUREMENT_HM = 0xE5,
+ TRIGGER_T_MEASUREMENT_NHM = 0xF3,
+ TRIGGER_RH_MEASUREMENT_NHM = 0xF5,
+ USER_REGISTER_W = 0xE6,
+ USER_REGISTER_R = 0xE7,
+ SOFT_RESET = 0xFE
+ };
+
+ static const uint16_t POLYNOMIAL;
+
+ char addr_;
+ I2C *pi2c_;
+ I2C &i2c_;
+
+ uint16_t readRaw(uint8_t cmd);
+ static bool crcChecksum(const uint8_t *data, uint8_t sz, uint8_t checksum);
+};
+
+#endif // SHT21_HPP_INCLUDED
--- a/main.cpp Thu Aug 10 13:25:37 2017 +0000
+++ b/main.cpp Wed Sep 13 13:36:04 2017 +0000
@@ -1,143 +1,5 @@
#include "mbed.h"
-
-/**
- * A simple library for SHT21 humidity and temperature sensor.
- * Based on the Arduino library.
- */
-
-class SHT21 {
-public:
- SHT21(PinName sda, PinName scl, char addr = (0x40 << 1));
- SHT21(I2C &i2c, char addr = (0x40 << 1));
-
- float temperature();
- float humidity();
-
- void reset();
- void serialNumber(uint8_t *serialNumber);
-
- ~SHT21();
-private:
- enum commands {
- TRIGGER_T_MEASUREMENT_HM = 0xE3,
- TRIGGER_RH_MEASUREMENT_HM = 0xE5,
- TRIGGER_T_MEASUREMENT_NHM = 0xF3,
- TRIGGER_RH_MEASUREMENT_NHM = 0xF5,
- USER_REGISTER_W = 0xE6,
- USER_REGISTER_R = 0xE7,
- SOFT_RESET = 0xFE
- };
-
- static const uint16_t POLYNOMIAL;
-
- char addr_;
- I2C *pi2c_;
- I2C &i2c_;
-
- uint16_t readRaw(uint8_t cmd);
- static bool crcChecksum(const uint8_t *data, uint8_t sz, uint8_t checksum);
-};
-
-const uint16_t SHT21::POLYNOMIAL = 0x131;
-
-SHT21::SHT21(PinName sda, PinName scl, char addr) :
- addr_(addr),
- pi2c_(new I2C(sda, scl)),
- i2c_(*pi2c_) {
-}
-
-SHT21::SHT21(I2C &i2c, char addr) :
- addr_(addr),
- pi2c_(NULL),
- i2c_(i2c) {
-}
-
-float SHT21::temperature() {
- uint16_t r = readRaw(TRIGGER_T_MEASUREMENT_HM);
- r &= ~0x0003;
- return (-46.85 + 175.72/65536 * (float) r);
-}
-
-float SHT21::humidity() {
- uint16_t r = readRaw(TRIGGER_RH_MEASUREMENT_HM);
- r &= ~0x0003;
- return (-6.0 + 125.0/65536 * (float) r);
-}
-
-void SHT21::reset() {
- uint8_t pcmd [] = { SOFT_RESET };
- i2c_.write(addr_, (const char *) pcmd, 1);
- wait_ms(15);
-}
-
-void SHT21::serialNumber(uint8_t *serialNumber) {
- uint8_t data[8];
- uint8_t pcmd0[2] = { 0xFA, 0x0F };
- uint8_t pcmd1[2] = { 0xFC, 0xC9 };
- uint8_t i = 0;
- i2c_.write(addr_, (const char *) pcmd0, 2);
- i2c_.read(addr_, (char *) data, 8);
-
- serialNumber[5] = data[i++];
- i++;
- serialNumber[4] = data[i++];
- i++;
- serialNumber[3] = data[i++];
- i++;
- serialNumber[2] = data[i++];
- i = 0;
-
- i2c_.write(addr_, (const char *) pcmd1, 2);
- i2c_.read(addr_, (char *) data, 6);
-
- serialNumber[1] = data[i++];
- serialNumber[0] = data[i++];
- i++;
- serialNumber[7] = data[i++];
- serialNumber[8] = data[i++];
- i = 0;
-}
-
-SHT21::~SHT21() {
- if (pi2c_) delete pi2c_;
-}
-
-uint16_t SHT21::readRaw(uint8_t cmd) {
- uint8_t checksum;
- uint8_t data[2];
- uint16_t result;
-
- uint8_t pcmd [] = { cmd };
-
- i2c_.write(addr_, (const char *) pcmd, 1);
- i2c_.read(addr_, (char *) data, 2);
- i2c_.read(addr_, (char *) &checksum, 1);
-
- result = data[0] << 8;
- result += data[1];
-
- if (crcChecksum(data, 2, checksum)) {
- reset();
- return 1;
- }
- return result;
-}
-
-bool SHT21::crcChecksum(const uint8_t *data, uint8_t sz, uint8_t checksum) {
- uint8_t crc = 0;
-
- for (uint8_t i = 0; i < sz; ++i) {
- crc ^= data[i];
- for (uint8_t j /* bit index */ = 8; j > 0; --j) {
- if (crc & 0x80)
- crc = (crc << 1) ^ POLYNOMIAL;
- else
- crc = (crc << 1);
- }
- }
-
- return crc == checksum;
-}
+#include "SHT21.hpp"
SHT21 sht21(PB_9 /* I2C_SDA */, PB_8 /* I2C_SCL */);
Serial pc(USBTX, USBRX);