mcp3208.h

00001 /**
00002  * @file mcp3208.h
00003  */
00004 
00005 #include "mbed.h"
00006 
00007 
00008 #ifndef MCP3208_H
00009 #define MCP3208_H
00010 
00011 
00012 /** Polarity setting for differential inputs.
00013  *
00014  * POL_EVEN_POSITIVE sets channel [0|2|4|6] as the positive side and channel
00015  * [1|3|5|7] as the negative side. POL_EVEN_NEGATIVE sets the opposite.
00016  */
00017 enum Polarity {
00018     POL_EVEN_POSITIVE,
00019     POL_EVEN_NEGATIVE
00020 };
00021 
00022 
00023 /** Class for interfacing to the MCP3208 SPI-based ADC.
00024  *
00025  * This class will also allow interfacing to the MCP3204, but only four
00026  * inputs are provided by that chip, as opposed to the eight of the MCP3208.
00027  */
00028 class MCP3208
00029 {
00030 public:
00031     /** Create an MCP3208 object.
00032      *
00033      * @param bus An SPI bus object.
00034      * @param cs The name of a pin to use as the chip select.
00035      */
00036     MCP3208(SPI bus, PinName cs);
00037     ~MCP3208();
00038     
00039     /** Read from a single-ended input.
00040      *
00041      * @param channel The channel number to read from.
00042      *
00043      * @param returns The sampled value as a float between 0.0 and 1.0.
00044      */
00045     float read_input(int channel);
00046     
00047     /** Read from a pair of differential inputs.
00048      *
00049      * In differential mode, the channels are referred to as 0 to 3, with
00050      * polarity set in a separate parameter. This avoids the user having to set
00051      * the polarity as part of the channel number or having channel numbers
00052      * increase by two (i.e. the channels being 0, 2, 4, and 6).
00053      *
00054      * @param channel The channel number to read from.
00055      * @param polarity The polarity of the differential signal.
00056      *
00057      * @param returns The sampled value as a float between 0.0 and 1.0.
00058      */
00059     float read_diff_input(int channel, Polarity polarity);
00060   
00061 private:
00062     DigitalOut m_cs;
00063     SPI m_bus;
00064     
00065     void select();
00066     void deselect();
00067 };
00068 
00069 
00070 #endif