Jimmy Hack / MCP4922

The MCP4922 is a 12 bit DAC. This library should provide easy access to its basic functionality.

Dependencies:   DAC

MCP4922.h@0:4e1ee1c4d3bb, 2012-07-04 (annotated)

Committer:
JimmyTheHack
Date:
Wed Jul 04 01:29:05 2012 +0000
Revision:
0:4e1ee1c4d3bb
updated SPI_DAC library

Who changed what in which revision?

UserRevisionLine numberNew contents of line
JimmyTheHack 0:4e1ee1c4d3bb 1 #ifndef MCP4922_H
JimmyTheHack 0:4e1ee1c4d3bb 2 #define MCP4922_H
JimmyTheHack 0:4e1ee1c4d3bb 3
JimmyTheHack 0:4e1ee1c4d3bb 4 #include "DAC_SPI.h"
JimmyTheHack 0:4e1ee1c4d3bb 5
JimmyTheHack 0:4e1ee1c4d3bb 6 /**
JimmyTheHack 0:4e1ee1c4d3bb 7 * The MCP4922 is a dual package 12 bit DAC. We should be able to produce two analog output voltages up to twice the externally wired voltage references (VrefA, VrefB).
JimmyTheHack 0:4e1ee1c4d3bb 8 The maximum voltage output is limited by the input voltage at V_DD which can go up to about 5.5V.
JimmyTheHack 0:4e1ee1c4d3bb 9
JimmyTheHack 0:4e1ee1c4d3bb 10 * Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/22250A.pdf
JimmyTheHack 0:4e1ee1c4d3bb 11
JimmyTheHack 0:4e1ee1c4d3bb 12 * All serial commands are 16 bit words. The highest 4 bits are control bits, while the last 12 are the data bits for the 12-bit DAC MCP4822.
JimmyTheHack 0:4e1ee1c4d3bb 13 * + bit 15: select which DAC to use.
JimmyTheHack 0:4e1ee1c4d3bb 14 * + bit 14: 0=buffered , 1= unbuffered
JimmyTheHack 0:4e1ee1c4d3bb 15 * + bit 13: 0= gain x2, 1= gain x1
JimmyTheHack 0:4e1ee1c4d3bb 16 * + bit 12: 0= DAC active, 1= shut down DAC
JimmyTheHack 0:4e1ee1c4d3bb 17 * + bit 11-0: Data bits for the DAC.
JimmyTheHack 0:4e1ee1c4d3bb 18 */
JimmyTheHack 0:4e1ee1c4d3bb 19 class MCP4922: public DAC_SPI
JimmyTheHack 0:4e1ee1c4d3bb 20 {
JimmyTheHack 0:4e1ee1c4d3bb 21 public:
JimmyTheHack 0:4e1ee1c4d3bb 22
JimmyTheHack 0:4e1ee1c4d3bb 23 /** Initializes the MCP 4922 DAC
JimmyTheHack 0:4e1ee1c4d3bb 24 *
JimmyTheHack 0:4e1ee1c4d3bb 25 * @param SPIchannelNum An int representing the SPI channel used by this DAC
JimmyTheHack 0:4e1ee1c4d3bb 26 * channel 0 for p5 and p7
JimmyTheHack 0:4e1ee1c4d3bb 27 * channel 1 for p11 and p13
JimmyTheHack 0:4e1ee1c4d3bb 28 * @param CS The chip select pin used to identify the device
JimmyTheHack 0:4e1ee1c4d3bb 29 * @param LDAC The LDAC pin used to synchronize updates of multiple devices
JimmyTheHack 0:4e1ee1c4d3bb 30 */
JimmyTheHack 0:4e1ee1c4d3bb 31 MCP4922(int SPIchannelNum, PinName CS, PinName LDAC);
JimmyTheHack 0:4e1ee1c4d3bb 32
JimmyTheHack 0:4e1ee1c4d3bb 33 /** Writes a value between 0-4095 to the currently selected DAC output
JimmyTheHack 0:4e1ee1c4d3bb 34 * @param DACvalue a value from 0-4095 to write to the DAC register
JimmyTheHack 0:4e1ee1c4d3bb 35 */
JimmyTheHack 0:4e1ee1c4d3bb 36 virtual void write(int DACvalue);
JimmyTheHack 0:4e1ee1c4d3bb 37
JimmyTheHack 0:4e1ee1c4d3bb 38 /** Writes a value in mV to the DAC outputs.
JimmyTheHack 0:4e1ee1c4d3bb 39 * The output will only be accurate if Vref is set to the appropriate voltage reference scaling factor.
JimmyTheHack 0:4e1ee1c4d3bb 40 * @param millivolte The desired voltage output in millivolts
JimmyTheHack 0:4e1ee1c4d3bb 41 */
JimmyTheHack 0:4e1ee1c4d3bb 42 virtual void write_mV(int millivolts);
JimmyTheHack 0:4e1ee1c4d3bb 43
JimmyTheHack 0:4e1ee1c4d3bb 44 /** If automatic updating is disabled, this will update the DAC output on command */
JimmyTheHack 0:4e1ee1c4d3bb 45 void update();
JimmyTheHack 0:4e1ee1c4d3bb 46
JimmyTheHack 0:4e1ee1c4d3bb 47 /** select whether to use DAC A or DAC B.
JimmyTheHack 0:4e1ee1c4d3bb 48 * @param DACnum 0 to modify DAC A, 1 to modify DAC B
JimmyTheHack 0:4e1ee1c4d3bb 49 */
JimmyTheHack 0:4e1ee1c4d3bb 50 virtual void select(char DACnum);
JimmyTheHack 0:4e1ee1c4d3bb 51
JimmyTheHack 0:4e1ee1c4d3bb 52 /** If true, the DAC output will update as soon as the output value is modified. If false, it will wait for an update command*/
JimmyTheHack 0:4e1ee1c4d3bb 53 bool autoUpdate;
JimmyTheHack 0:4e1ee1c4d3bb 54
JimmyTheHack 0:4e1ee1c4d3bb 55 /** The currently selected DAC channel. 0 for DAC A, 1 for DAC B*/
JimmyTheHack 0:4e1ee1c4d3bb 56 char DACselect;
JimmyTheHack 0:4e1ee1c4d3bb 57
JimmyTheHack 0:4e1ee1c4d3bb 58 /** The output scaling factor in mV for channel A.
JimmyTheHack 0:4e1ee1c4d3bb 59 * The voltage wired to Vref will be used as the scaling factor which the DAC will use in producing the output voltage.
JimmyTheHack 0:4e1ee1c4d3bb 60 * If using the write_mV function, it is important that Vref is properly set. This library uses 5000mV by default.
JimmyTheHack 0:4e1ee1c4d3bb 61 */
JimmyTheHack 0:4e1ee1c4d3bb 62 int VrefA;
JimmyTheHack 0:4e1ee1c4d3bb 63 /** The output scaling factor in mV for channel B.
JimmyTheHack 0:4e1ee1c4d3bb 64 * The voltage wired to Vref will be used as the scaling factor which the DAC will use in producing the output voltage.
JimmyTheHack 0:4e1ee1c4d3bb 65 * If using the write_mV function, it is important that Vref is properly set. This library uses 5000mV by default.
JimmyTheHack 0:4e1ee1c4d3bb 66 */
JimmyTheHack 0:4e1ee1c4d3bb 67 int VrefB;
JimmyTheHack 0:4e1ee1c4d3bb 68
JimmyTheHack 0:4e1ee1c4d3bb 69 /** Manually set the gain of the DAC. The only valid values are 1 and 2. The default gain is x1 to match the wired reference voltage*/
JimmyTheHack 0:4e1ee1c4d3bb 70 void setGain(int gain_value);
JimmyTheHack 0:4e1ee1c4d3bb 71
JimmyTheHack 0:4e1ee1c4d3bb 72 /** Turn on or off the output buffer. The default value for the buffer is off. See section 4.1.2 of the datasheet for more information. */
JimmyTheHack 0:4e1ee1c4d3bb 73 char buffered;
JimmyTheHack 0:4e1ee1c4d3bb 74
JimmyTheHack 0:4e1ee1c4d3bb 75 private:
JimmyTheHack 0:4e1ee1c4d3bb 76 /** The output gain bit of the DAC. If set to 0, gain is x2. If set to 1 gain is x1. The default gain is 1.*/
JimmyTheHack 0:4e1ee1c4d3bb 77 bool gain;
JimmyTheHack 0:4e1ee1c4d3bb 78 };
JimmyTheHack 0:4e1ee1c4d3bb 79
JimmyTheHack 0:4e1ee1c4d3bb 80 #endif //MCP4922_H