Jimmy Hack / MAX500

The MAX500 is an 8 bit DAC that can output to higher voltages (~12V). The chip has 4 onboard DAC channels.

Dependencies:   DAC

MAX500.h@0:b74d88185698, 2012-07-03 (annotated)

Committer:
JimmyTheHack
Date:
Tue Jul 03 03:22:59 2012 +0000
Revision:
0:b74d88185698
updated DAC_SPI library to have virtual select function

Who changed what in which revision?

UserRevisionLine numberNew contents of line
JimmyTheHack 0:b74d88185698 1 #ifndef MAX500_H
JimmyTheHack 0:b74d88185698 2 #define MAX500_H
JimmyTheHack 0:b74d88185698 3
JimmyTheHack 0:b74d88185698 4 #include "DAC_SPI.h"
JimmyTheHack 0:b74d88185698 5
JimmyTheHack 0:b74d88185698 6 /**
JimmyTheHack 0:b74d88185698 7 * The MAX500 is a quad package 8 bit DAC. We should be able to produce four analog output voltages up to the externally wired voltage references (VrefA/B, VrefC, VrefD).
JimmyTheHack 0:b74d88185698 8 The maximum voltage output is recommended to be about 4V less than the power supply voltage, although getting a 12V output from a 15V power supply is possible.
JimmyTheHack 0:b74d88185698 9 *
JimmyTheHack 0:b74d88185698 10 * Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX500.pdf
JimmyTheHack 0:b74d88185698 11 *
JimmyTheHack 0:b74d88185698 12 * We use the "3-wire" serial interface since it seems to be more compatible with the mbed Serial library timing than the "2-wire" interface. The 2-wire interface uses a somewhat non-standard timing scheme
JimmyTheHack 0:b74d88185698 13 * and may require custom code support.
JimmyTheHack 0:b74d88185698 14 *
JimmyTheHack 0:b74d88185698 15 * All serial commands are 10 bit words. The highest 2 bits are control bits, while the last 8 are the data bits for the 8-bit DAC MAX500.
JimmyTheHack 0:b74d88185698 16 * + bit 13-12: choose which DAC to use
JimmyTheHack 0:b74d88185698 17 * + bit 11-0: Data bits for the DAC.
JimmyTheHack 0:b74d88185698 18 */
JimmyTheHack 0:b74d88185698 19 class MAX500: public DAC_SPI
JimmyTheHack 0:b74d88185698 20 {
JimmyTheHack 0:b74d88185698 21 public:
JimmyTheHack 0:b74d88185698 22
JimmyTheHack 0:b74d88185698 23 /** Initializes the MAX 500 DAC
JimmyTheHack 0:b74d88185698 24 *
JimmyTheHack 0:b74d88185698 25 * @param SPIchannelNum An int representing the SPI channel used by this DAC
JimmyTheHack 0:b74d88185698 26 * channel 0 for p5 and p7
JimmyTheHack 0:b74d88185698 27 * channel 1 for p11 and p13
JimmyTheHack 0:b74d88185698 28 * @param LOAD The chip select pin (CS) used to identify the device
JimmyTheHack 0:b74d88185698 29 * @param LDAC The LDAC pin used to synchronize updates of multiple devices
JimmyTheHack 0:b74d88185698 30 */
JimmyTheHack 0:b74d88185698 31 MAX500(int SPIchannelNum, PinName LOAD, PinName LDAC);
JimmyTheHack 0:b74d88185698 32
JimmyTheHack 0:b74d88185698 33 /** Writes a value between 0-255 to the currently selected DAC output
JimmyTheHack 0:b74d88185698 34 * @param DACvalue a value from 0-255 to write to the DAC register
JimmyTheHack 0:b74d88185698 35 */
JimmyTheHack 0:b74d88185698 36 virtual void write(int DACvalue);
JimmyTheHack 0:b74d88185698 37
JimmyTheHack 0:b74d88185698 38 /** Writes a value in mV to the DAC outputs.
JimmyTheHack 0:b74d88185698 39 * The output will only be accurate if Vref is set to the appropriate voltage reference scaling factor.
JimmyTheHack 0:b74d88185698 40 * @param millivolts The desired voltage output in millivolts
JimmyTheHack 0:b74d88185698 41 */
JimmyTheHack 0:b74d88185698 42 virtual void write_mV(int millivolts);
JimmyTheHack 0:b74d88185698 43
JimmyTheHack 0:b74d88185698 44 /** If automatic updating is disabled, this will update the DAC output on command */
JimmyTheHack 0:b74d88185698 45 void update();
JimmyTheHack 0:b74d88185698 46
JimmyTheHack 0:b74d88185698 47 /** select whether to use DAC A or DAC B.
JimmyTheHack 0:b74d88185698 48 * @param DACnum 0 to modify DAC A, 1 to modify DAC B
JimmyTheHack 0:b74d88185698 49 */
JimmyTheHack 0:b74d88185698 50 virtual void select(char DACnum);
JimmyTheHack 0:b74d88185698 51
JimmyTheHack 0:b74d88185698 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:b74d88185698 53 bool autoUpdate;
JimmyTheHack 0:b74d88185698 54
JimmyTheHack 0:b74d88185698 55 /** The currently selected DAC channel. 0 for DAC A, 1 for DAC B*/
JimmyTheHack 0:b74d88185698 56 char DACselect;
JimmyTheHack 0:b74d88185698 57
JimmyTheHack 0:b74d88185698 58 /** The output scaling factor in mV for channels A and B.
JimmyTheHack 0:b74d88185698 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:b74d88185698 60 * If using the write_mV function, it is important that Vref is properly set. This library uses 5000mV by default.
JimmyTheHack 0:b74d88185698 61 */
JimmyTheHack 0:b74d88185698 62 int VrefAB;
JimmyTheHack 0:b74d88185698 63 /** The output scaling factor in mV for channel C.
JimmyTheHack 0:b74d88185698 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:b74d88185698 65 * If using the write_mV function, it is important that Vref is properly set. This library uses 5000mV by default.
JimmyTheHack 0:b74d88185698 66 */
JimmyTheHack 0:b74d88185698 67 int VrefC;
JimmyTheHack 0:b74d88185698 68 /** The output scaling factor in mV for channel D.
JimmyTheHack 0:b74d88185698 69 * The voltage wired to Vref will be used as the scaling factor which the DAC will use in producing the output voltage.
JimmyTheHack 0:b74d88185698 70 * If using the write_mV function, it is important that Vref is properly set. This library uses 5000mV by default.
JimmyTheHack 0:b74d88185698 71 */
JimmyTheHack 0:b74d88185698 72 int VrefD;
JimmyTheHack 0:b74d88185698 73
JimmyTheHack 0:b74d88185698 74
JimmyTheHack 0:b74d88185698 75
JimmyTheHack 0:b74d88185698 76 };
JimmyTheHack 0:b74d88185698 77
JimmyTheHack 0:b74d88185698 78 #endif //MAX500_H