Diff: Hx711.h

Revision:

0:5fa72cacd94b

Child:

1:197ef68ad6de

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Hx711.h	Wed Jun 15 15:23:54 2016 +0000
@@ -0,0 +1,154 @@
+#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.
+ * This library is a port of the Arduino library at 
+ * https://github.com/bogde/HX711
+ * It works with the FRDM K22F.
+ */
+class Hx711 {
+public:
+    /**
+     * Create an Hx711 ADC object
+     * @param pin_sck PinName of the clock pin (digital output)
+     * @param pin_dt PinName of the data pin (digital input)
+     * @param offset offset for sensor values
+     * @param scale scale factor to obtain real values
+     * @param gain channel selection is made by passing the appropriate gain: 
+     *      128 or 64 for channel A, 32 for channel B
+     */
+    Hx711(PinName pin_sck, PinName pin_dt, int offset, float scale, uint8_t gain = 128) :
+        sck_(pin_sck),
+        dt_(pin_dt) {
+        set_offset(offset);
+        set_scale(scale);
+        set_gain(gain);
+    }
+    
+    /**
+     * Create an Hx711 ADC object with zero offset and 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
+     */
+    Hx711(PinName pin_sck, PinName pin_dt, uint8_t gain = 128) :
+        sck_(pin_sck),
+        dt_(pin_dt) {
+        set_offset(0);
+        set_scale(1.0f);
+        set_gain(gain);
+    }
+
+    /**
+     * Check if the sensor is ready
+     * from the datasheet: When output data is not ready for retrieval, 
+     * 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
+     */
+    bool is_ready() {
+        return dt_.read() == LOW;
+    }
+    
+    /**
+     * Waits for the chip to be ready and returns a raw int reading
+     * @return int sensor output value
+     */
+    int readRaw();
+    
+    /**
+     * Obtain offset and scaled sensor output; i.e. a real value
+     * @return float
+     */
+    float read() {
+        return ((float)(readRaw() - get_offset())) * get_scale();
+    }
+    
+    /**
+     * Puts the chip into power down mode
+     */
+    void power_down() {
+        sck_.write(LOW);
+        sck_.write(HIGH);
+    }
+
+    /**
+     * Wakes up the chip after power down mode
+     */
+    void power_up() {
+        sck_.write(LOW);
+    }
+
+    /**
+     * Set the gain factor; takes effect only after a call to read()
+     * channel A can be set for a 128 or 64 gain; channel B has a fixed 32 gain
+     * depending on the parameter, the channel is also set to either A or B
+     * Ensures that gain_ = 128, 64 or 32
+     * @param gain 128, 64 or 32
+     */
+    void set_gain(uint8_t gain = 128);
+    
+    /**
+     * Obtain current gain
+     * @return gain_
+     */
+    uint8_t get_gain() {
+        return gain_;
+    }
+
+    /**
+     * Set the scale factor
+     * @param scale desired scale
+     */
+    void set_scale(float scale = 1.f) { 
+        scale_ = scale; 
+    };
+
+    /**
+     * Get sensor scale factor
+     * @return scale_
+     */
+    float get_scale() { 
+        return scale_; 
+    }
+
+    /**
+     * Set the sensor offset
+     * @param offset the desired offset
+     */
+    void set_offset(int offset = 0) { 
+        offset_ = offset; 
+    }
+
+    /**
+     * Get current sensor offset
+     * @return offset_
+     */
+    int get_offset() { return offset_; }
+    
+
+private:
+    DigitalOut sck_;    // clock line
+    DigitalIn dt_;      // data line 
+
+    uint8_t gain_;      // amplification factor at chip
+    int offset_;        // zet zero
+    float scale_;       // scale output
+
+    /**
+     * Port of the Arduino shiftIn function; shifts a byte one bit at a time
+     * @param bit_order LSBFIRST or MSBFIRST
+     * @return incoming but
+     */
+    uint8_t shiftIn(uint8_t bit_order);
+};
+
+#endif
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