Productize / PCT2075

Driver for the NXP PCT2075 digital temperature sensor and thermal watchdog

NXP PCT2075 temperature sensor driver for mbed

This library is a driver for the [NXP PCT2075](http://www.nxp.com/products/sensors/i2c-temperature-voltage-monitors/ic-bus-fm-plus-1-degree-c-accuracy-digital-temperature-sensor-and-thermal-watchdog:PCT2075). It only handles the I2C communication with the sensor, it does not handle the OS interrupt line. The [mbed InterruptIn](https://developer.mbed.org/handbook/InterruptIn) library can be used for this.

example usage

#include <mbed.h>
#include <PCT2075.h>
 
Serial s(USBTX, USBRX); // tx, rx
 
InterruptIn TempPinInt(PC4);
LowPowerTicker ticker;
 
static volatile bool temp_int = false;
static volatile bool tick_int = false;
 
int main( void )
{
    TempPinInt.mode(PullUp);
 
    PCT2075::Configuration config = {
        PCT2075::OS_FAULT_QUE_1,
        PCT2075::OS_ACTIVE_LOW,
        PCT2075::OS_MODE_INTERRUPT,
        PCT2075::DEVICE_MODE_SHUTDOWN
    };
    temp_sensor.set_configuration(config);
    temp_sensor.set_idle_time(PCT2075::TIDLE_MAX);
    
    temp_sensor.set_hyst_temperature(2000);
    temp_sensor.set_os_temperature(2500);
    
    TempPinInt.fall(&on_fall);
    ticker.attach(&tick, 2.0);
 
    while(true) {
        sleep(); // wait to be woken up by ticker or temp sensor
 
        if (tick_int) {
            s.printf("Tick\r\n");
            config.device_mode = PCT2075::DEVICE_MODE_NORMAL;
            temp_sensor.set_configuration(config);
            tick_int = false;
        }
 
        if (temp_int) {
            config.device_mode = PCT2075::DEVICE_MODE_SHUTDOWN;
            temp_sensor.set_configuration(config);
            uint16_t t = temp_sensor.read_temperature();
            s.printf("Temperature: %d\r\n", t);
            temp_int = false;
        }
    }
}

Diff: PCT2075.h

Revision:
1:a2b7889eb4e9
diff -r 396665cc3ea0 -r a2b7889eb4e9 PCT2075.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCT2075.h	Fri Sep 23 15:38:34 2016 +0200
@@ -0,0 +1,109 @@
+#ifndef _pct2075_h_
+#define _pct2075_h_
+
+#include "mbed.h"
+
+class PCT2075 {
+  private:
+    I2C     &i2c;
+    uint8_t  address_write;
+    uint8_t  address_read;
+
+  public:
+    static const int16_t  TEMP_MAX  = 12500; // centi-°C
+    static const int16_t  TEMP_MIN  = -5500; // centi-°C
+    static const uint16_t TIDLE_MAX =  3100; // ms
+    static const uint16_t TIDLE_MIN =   100; // ms
+
+    // Fault queue is defined as the number of faults that must occur
+    // consecutively to activate the OS output. It is provided to avoid false
+    // tripping due to noise. Because faults are determined at the end of data
+    // conversions, fault queue is also defined as the number of consecutive
+    // conversions returning a temperature trip.
+    enum OSFaultQue {
+        OS_FAULT_QUE_1 = 0,
+        OS_FAULT_QUE_2 = 1,
+        OS_FAULT_QUE_4 = 2,
+        OS_FAULT_QUE_6 = 3
+    };
+
+    enum OSPolarity {
+        OS_ACTIVE_LOW  = 0,
+        OS_ACTIVE_HIGH = 1
+    };
+
+    enum OSMode {
+        OS_MODE_COMP      = 0,
+        OS_MODE_INTERRUPT = 1
+    };
+
+    // In shutdown mode, the PCT2075 draws a small current of <1.0 µA and the
+    // power dissipation is minimized; the temperature conversion stops, but the
+    // I2C-bus interface remains active and register write/read operation can be
+    // performed. When the shutdown is set, the OS output will be unchanged in
+    // comparator mode and reset in interrupt mode.
+    enum DeviceMode {
+        DEVICE_MODE_NORMAL   = 0,
+        DEVICE_MODE_SHUTDOWN = 1
+    };
+
+    struct Configuration {
+         OSFaultQue os_fault_que;
+         OSPolarity os_polarity;
+         OSMode     os_mode;
+         DeviceMode device_mode;
+    };
+
+    PCT2075 (I2C &i2c_obj, uint8_t address = 0x48);
+
+    ~PCT2075();
+    int16_t PCT2075_os_temp;
+    int16_t PCT2075_hyst_temp;
+    uint8_t PCT2075_temp_idle_cycle;
+
+    Configuration get_configuration();
+    void set_configuration(Configuration& config);
+
+    // Shorthand functions for changing one parameter of the configuration
+    // without changing the other parameters.
+    // Note: When changing multiple parameters it is more efficient to batch
+    // them using set_configuration.
+    void set_os_fault_queue(OSFaultQue fault_que);
+    void set_os_polarity(OSPolarity polarity);
+    void set_os_mode(OSMode mode);
+    void set_device_mode(DeviceMode mode);
+    void shutdown_mode();
+    void normal_mode();
+
+    // Returns the temperature in centi-degrees C,
+    // resolution of .125 degrees, rounded down to .1 degrees
+    int16_t read_temperature();
+
+    // Get the OS temperature in centi-degrees C,
+    // rounded to .5 degrees C
+    int16_t get_os_temperature();
+    // Set the OS temperature in centi-degrees C,
+    // rounded to .5 degrees C
+    void set_os_temperature(int16_t temperature);
+
+    // Get the hysteresis temperature in centi-degrees C,
+    // rounded to .5 degrees C
+    int16_t get_hyst_temperature();
+    // Set the hysteresis temperature in centi-degrees C,
+    // rounded to .5 degrees C
+    void set_hyst_temperature(int16_t temperature);
+
+    // Get idle time in ms, resolution of 100ms (deci-seconds)
+    uint16_t get_idle_time();
+    // Set idle time in ms, rounded down to 100ms (deci-seconds)
+    // In normal operation mode, the temp-to-digital conversion is executed
+    // every 100 ms or other programmed value and the Temp register is updated
+    // at the end of each conversion. During each ‘conversion period’ (Tconv) of
+    // about 100 ms, the device takes only about 28 ms, called ‘temperature
+    // conversion time’ (tconv(T)), to complete a temperature-to-data conversion
+    // and then becomes idle for the time remaining in the period. This feature
+    // is implemented to significantly reduce the device power dissipation.
+    void set_idle_time(uint16_t time);
+};
+
+#endif // _PCT2075_H_