Revision 4:ac75d4d62471, committed 2019-01-30

Comitter:

phonemacro

Date:

Wed Jan 30 02:13:05 2019 +0000

Parent:

3:f39791139435

Child:

5:8e70ec0923e2

Commit message:

correct calculations for signed temperatures

Changed in this revision

--- a/max31723.cpp	Mon Jan 28 00:39:50 2019 +0000
+++ b/max31723.cpp	Wed Jan 30 02:13:05 2019 +0000
@@ -37,7 +37,8 @@
         uint8_t lsb;
         uint8_t msb;
     };
-    uint16_t wrd;
+    uint16_t uwrd;
+    int16_t swrd;
 };
  
 MAX31723::MAX31723(SPI &spi, DigitalOut &ce_pin) : m_spi(spi), m_chip_enable(ce_pin)
@@ -47,20 +48,33 @@
  
 int MAX31723::write_reg(uint8_t val, uint8_t reg)
 {
-    m_chip_enable = 1;
-    m_spi.write(reg);
-    m_spi.write(val);
-    m_chip_enable = 0;
-    return MAX31723_NO_ERROR;
+    if (reg == (MAX31723_REG_CFG | MAX31723_WRITE_MASK) ||
+            (reg >= (MAX31723_REG_TRIP_HI_LSB | MAX31723_WRITE_MASK) &&
+            reg <= (MAX31723_REG_MAX | MAX31723_WRITE_MASK)) ) {
+        m_chip_enable = 1;
+        m_spi.write(reg);
+        m_spi.write(val);
+        m_chip_enable = 0;
+        return MAX31723_NO_ERROR;
+    } else {
+        printf("Input write_reg is invalid, 0x%02X \r\n", reg);
+        return MAX31723_ERROR;
+    }
 }
  
 int MAX31723::read_reg(uint8_t &val, uint8_t reg)
 {
-    m_chip_enable = 1;
-    m_spi.write(reg);
-    val = m_spi.write(0);
-    m_chip_enable = 0;
-    return MAX31723_NO_ERROR;
+    if (reg <= MAX31723_REG_MAX) {
+        m_chip_enable = 1;
+        wait(.001);
+        m_spi.write(reg);
+        val = m_spi.write(0);
+        m_chip_enable = 0;
+        return MAX31723_NO_ERROR;
+    } else {
+        printf("Input read_reg is invalid, 0x%02X \r\n", reg);
+        return MAX31723_ERROR;
+    }
 }
 
 int MAX31723::perform_one_shot(uint8_t resolution, uint8_t interrupt_mode)
@@ -103,8 +117,8 @@
     if (reg >= MAX31723_REG_TEMP_LSB && reg <= MAX31723_REG_MAX) {
         read_reg(raw.lsb, reg);
         read_reg(raw.msb, reg+1);
-        raw.wrd =  raw.wrd >> MAX31723_UNUSED_BITS;
-        temperature = raw.wrd * MAX31723_CF_LSB;
+        raw.swrd = raw.swrd >> MAX31723_UNUSED_BITS;
+        temperature = raw.swrd * MAX31723_CF_LSB;
         return temperature;
     } else {
         printf("Input read_registers_as_temperature is invalid, %d r\n",

--- a/max31723.h	Mon Jan 28 00:39:50 2019 +0000
+++ b/max31723.h	Wed Jan 30 02:13:05 2019 +0000
@@ -72,7 +72,7 @@
 
 #define MAX31723_NVRAM_WRITE_TIME_MSEC  0.015
 
-#define MAX31723_CF_LSB                 0.0625f
+#define MAX31723_CF_LSB                 0.0625
 #define MAX31723_UNUSED_BITS            4
 
 /**
@@ -111,6 +111,14 @@
     MAX31723(SPI &spi, DigitalOut &ce_pin); 
 
     /** 
+     * @brief Read a value from a register
+     * @param val - 8-bit value read from the register
+     * @param reg - register address
+     * @return 0 on success, negative number on failure
+     */
+    int read_reg(uint8_t &val, uint8_t reg);
+
+    /** 
      * @brief Write a value to a register
      * @param val - 8-bit value to write to the register
      * @param reg - register address
@@ -141,6 +149,12 @@
      */
     int perform_one_shot_comparator(uint8_t resolution);
 
+
+    /** 
+     * @brief Reads the configuration register
+     * @return value of the configuration register
+     */
+    uint8_t read_cfg();
     /** 
      * @brief Converts Celcius degrees to Fahrenheit
      * @param temp_c - the temperature in Celsius degrees
@@ -148,13 +162,6 @@
      */
     float celsius_to_fahrenheit(float temp_c);
 
-    /** 
-     * @brief Reads the configuration register
-     * @return value of the configuration register
-     */
-    uint8_t read_cfg();
-
-
     /************************************************************
      * @brief Default destructor for MAX31723 Class.  
      *
@@ -179,13 +186,6 @@
 
 
     private:
-    /** 
-     * @brief Read a value from a register
-     * @param val - 8-bit value read from the register
-     * @param reg - register address
-     * @return 0 on success, negative number on failure
-     */
-    int read_reg(uint8_t &val, uint8_t reg);
 
     /* SPI object */
     SPI &m_spi;