Diff: Hx711.h

Revision:

1:197ef68ad6de

Parent:

0:5fa72cacd94b

Child:

2:f118f8c456a4

--- a/Hx711.h	Wed Jun 15 15:23:54 2016 +0000
+++ b/Hx711.h	Thu Jun 16 07:31:43 2016 +0000
@@ -1,11 +1,6 @@
 #ifndef _HX711_H_
 #define _HX711_H_
 
-#define LSBFIRST 0
-#define MSBFIRST 1
-#define LOW 0
-#define HIGH 1
-
 /**
  * Class for communication with the HX711 24-Bit Analog-to-Digital 
  * Converter (ADC) for Weigh Scales by AVIA Semiconductor.
@@ -14,7 +9,9 @@
  * It works with the FRDM K22F.
  */
 class Hx711 {
+
 public:
+
     /**
      * Create an Hx711 ADC object
      * @param pin_sck PinName of the clock pin (digital output)
@@ -33,11 +30,12 @@
     }
     
     /**
-     * Create an Hx711 ADC object with zero offset and scaling
+     * Create an Hx711 ADC object with zero offset and unit scaling
      * @param pin_sck PinName of the clock pin (digital output)
      * @param pin_dt PinName of the data pin (digital input)
      * @param gain channel selection is made by passing the appropriate gain: 
      *      128 or 64 for channel A, 32 for channel B
+     * TODO: constructor overloading is not allowed?
      */
     Hx711(PinName pin_sck, PinName pin_dt, uint8_t gain = 128) :
         sck_(pin_sck),
@@ -53,6 +51,8 @@
      * digital output pin DOUT is high. Serial clock input PD_SCK should be low. 
      * When DOUT goes to low, it indicates data is ready for retrieval.
      * @return true if dt_.read() == LOW
+     * TODO: this is not ideal; the programm will hang if the chip never
+     * becomes ready...
      */
     bool is_ready() {
         return dt_.read() == LOW;
@@ -136,12 +136,18 @@
     
 
 private:
+
+    static const uint8_t LSBFIRST = 0; // least significant bit first
+    static const uint8_t MSBFIRST = 1; // most significant bit first
+    static const uint8_t LOW      = 0; // digital low
+    static const uint8_t HIGH     = 1; // digital high
+
     DigitalOut sck_;    // clock line
     DigitalIn dt_;      // data line 
 
     uint8_t gain_;      // amplification factor at chip
-    int offset_;        // zet zero
-    float scale_;       // scale output
+    int offset_;        // offset chip value
+    float scale_;       // scale output after offset
 
     /**
      * Port of the Arduino shiftIn function; shifts a byte one bit at a time