Revision 8:e310e55a687b, committed 2019-02-13

Comitter:

phonemacro

Date:

Wed Feb 13 22:26:50 2019 +0000

Parent:

7:92004aaa3e4d

Commit message:

Correct logic for negative values.

Changed in this revision

diff -r 92004aaa3e4d -r e310e55a687b max31723.cpp
--- a/max31723.cpp	Tue Feb 12 22:58:59 2019 +0000
+++ b/max31723.cpp	Wed Feb 13 22:26:50 2019 +0000
@@ -37,6 +37,10 @@
         uint8_t lsb;
         uint8_t msb;
     };
+    struct {
+        uint16_t magnitude_bits:15;
+        uint16_t sign_bit:1;
+    };
     uint16_t uwrd;
     int16_t swrd;
 };
@@ -70,12 +74,14 @@
 
 float MAX31723::read_reg_as_temperature(uint8_t reg)
 {
-    max31723_raw_data raw;
+    max31723_raw_data tmp;
     float temperature;
     if (reg >= MAX31723_REG_TEMP_LSB && reg <= MAX31723_REG_MAX) {
-        read_reg(raw.lsb, reg);
-        read_reg(raw.msb, reg+1);
-        temperature = raw.swrd * MAX31723_CF_LSB;
+        read_reg(tmp.lsb, reg);
+        read_reg(tmp.msb, reg+1);
+        temperature = tmp.magnitude_bits * MAX31723_CF_LSB;
+        if (tmp.sign_bit)
+            temperature = -temperature;
         return temperature;
     } else {
         printf("Input read_registers_as_temperature is invalid, %d r\n",
@@ -129,8 +135,13 @@
 {
     int ret;
     max31723_raw_data raw;
+    raw.uwrd = 0;
+    if (temperature < 0) {
+        raw.sign_bit = 1;
+        temperature = -temperature;
+    }
     temperature /= MAX31723_CF_LSB;
-    raw.swrd = int16_t(temperature);
+    raw.magnitude_bits = uint16_t(temperature);
     ret = write_reg(raw.lsb, MAX31723_WRITE_MASK | MAX31723_REG_TRIP_LO_LSB);
     wait(.015);
     ret = write_reg(raw.msb, MAX31723_WRITE_MASK | MAX31723_REG_TRIP_LO_MSB);
@@ -142,8 +153,13 @@
 {
     int ret;
     max31723_raw_data raw;
+    raw.uwrd = 0;
+    if (temperature < 0) {
+        raw.sign_bit = 1;
+        temperature = -temperature;
+    }
     temperature /= MAX31723_CF_LSB;
-    raw.swrd = int16_t(temperature);
+    raw.magnitude_bits = uint16_t(temperature);
     ret = write_reg(raw.lsb, MAX31723_WRITE_MASK | MAX31723_REG_TRIP_HI_LSB);
     wait(.015);
     ret = write_reg(raw.msb, MAX31723_WRITE_MASK | MAX31723_REG_TRIP_HI_MSB);

diff -r 92004aaa3e4d -r e310e55a687b max31723.h
--- a/max31723.h	Tue Feb 12 22:58:59 2019 +0000
+++ b/max31723.h	Wed Feb 13 22:26:50 2019 +0000
@@ -1,5 +1,5 @@
 /*******************************************************************************
-* Copyright (C) 2018 Maxim Integrated Products, Inc., All Rights Reserved.
+* Copyright (C) 2019 Maxim Integrated Products, Inc., All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
@@ -78,7 +78,7 @@
 /**
  * @brief 9-bit to 12bit device temperature sensor with digital-to-analog converters (DACs)
  *        for the MAX31723.
- * @version 1.0000.0003
+ * @version 1.0000.0004
  *
  * @details The MAX31722/MAX31723 provides device temperature readings
  * for thermostats and thermometers. Communications may be either SPI or