Diff: mcp342x.h

Revision:

1:c4da9889ff85

Parent:

0:7dbf7356da6b

Child:

2:639a5612903f

--- a/mcp342x.h	Wed Jun 15 10:37:24 2016 +0000
+++ b/mcp342x.h	Wed Jun 22 12:22:40 2016 +0000
@@ -21,6 +21,8 @@
 
 #include "mbed.h"
 
+#define COMMAND_N_BYTES 5
+
 /**
  * @brief Microchip analog-to-digital converter MCP3422/3/4
  *
@@ -53,13 +55,13 @@
  *
  *     while(1){
  *         // Channel 2 was selected above. Read data from this channel.
- *         long chan2_val = mcp_adc.read();
+ *         float chan2_val = mcp_adc.read_volts();
  *
  *         // Select now channel 1 and read it.
  *         mcp_adc.set_channel(MCP342x::CHANNEL_1);
- *         long chan1_val = mcp_adc.read();
+ *         float chan1_val = mcp_adc.read_volts();
  *
- *         printf("CH1 %i  CH2 %i\r\n", chan1_val, chan2_val);
+ *         printf("CH1 %.3f; CH2 %.3f\r\n", chan1_val, chan2_val);
  *         wait(5);
  *     }
  * }
@@ -160,36 +162,43 @@
     void set_pga(mcp342x_pga_t pga);
 
     /**
-    * Read the ADC value. The value will be that read from the channel
-    * set previously (`set_channel`)
+    * Read the ADC value. The value will be that read from whatever
+    * channel was set previously (`set_channel`).
     *
     * @return Analog measurement in raw data (integer)
     */
-    long read();
+    uint32_t read();
 
     /**
-    * Read the ADC value in volts. The value will be that read from the
-    * channel set previously (`set_channel`).
+    * Read the ADC value in volts. The value will be that read from
+    * whatever channel was set previously (`set_channel`).
     *
     * The data are coded in two's complements format, and the final
     * voltage is also a function of the resolution and gain settings.
-    * This function follows the equations presented in the device's
-    * datasheet (Microchip DS22088C), Section 4.9.
+    * This function follows the equations presented in Section 4.9 of
+    * the device's datasheet (Microchip DS22088C).
     *
     * @return Analog measurement in volts (float)
     */
     float read_volts();
 
+    //void start_conversion(void); For one-shot mode.
+
 private:
-    uint8_t _address;
+    // Variables and functions for I2C communication.
     I2C *_i2c;
-    uint8_t _resolution;
-    uint8_t _pga;
-    char _configuration[1];
+    uint8_t _address;
+    char _i2c_command[COMMAND_N_BYTES];
+    uint8_t _configuration;
     static const uint8_t _device_code = 0b1101; // Hardcoded in factory
     void _write_configuration();
+
+    // Variables needed for converting digital output codes to real
+    // values (i.e. voltage).
+    mcp342x_resolution_t _resolution;
+    uint8_t _pga;
+    float _lsb;
+    uint32_t _max_code;
 };
 
-//void mcp342x_start_conversion(void); For one-shot mode.
-
 #endif