Diamond Power Products MM-48-AT user manual Analog Output Overview

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10. ANALOG OUTPUT OVERVIEW

10.1 Description

Diamond-MM-48-AT uses an 8-channel 12-bit D/A converter (DAC) to provide 8 analog voltage outputs. A 12-bit DAC can generate output voltages with the precision of a 12-bit binary number. The maximum value of a 12-bit binary number is 212 - 1, or 4095, so the full range of numerical values that you can write to the analog outputs on Diamond-MM-48-AT is 0 - 4095. The value 0 always corresponds to the lowest voltage in the output range, and the value 4095 always corresponds to the highest voltage.

⇒Note: In this manual, the terms analog output, D/A, and DAC are all used interchangeably to mean the same thing.

10.2D/A Resolution

The resolution is the smallest possible change in output voltage. For a 12-bit DAC the resolution is 1/(212), or 1/4096, of the full-scale output range. This smallest change results from an increase or decrease of 1 in the D/A code, and so this change is referred to as 1 LSB, or 1 least significant bit. The value of this LSB is calculated based on the output range of the circuit. On the Diamond-MM-48-AT, the output range is fixed at 0-4.096V, making the formula simple:

1 D/A LSB = 4.096V / 4096 = 1mV

10.3 D/A Conversion Formulas and Tables

The formulas below explain how to convert between D/A codes and output voltages.

Conversion Formulas for Unipolar Output Ranges

Output voltage = D/A code x 1mV

D/A code = Desired output voltage in mV

Example: Desired output voltage = 1.234V = 1234mV; D/A code = 1234

Here is an illustration of the relationship between D/A code and output voltage for a unipolar output range (VREF = Reference voltage):

D/A Code Output voltage for 0–4.096V range

00.000V

10.001V

20.001V

. . . . . .

4095 4.095V

10.4 D/A Output Current

The output current capability of the 4 analog outputs varies according to the output voltage. Output current can be either sink or source, depending on the load characteristics. Normally the output will drive a voltage to ground, in which case the output is sourcing current.

D/A voltage	Sink current, max	Source current, max
0-0.200V	-0.5mA	4.0mA
0.201V-0.500V	-1.0mA	4.0mA
0.501V-0.900V	-2.0mA	4.0mA
0.901V-4.095V	-4.0mA	4.0mA
		Diamond-MM-48-AT User Manual V1.01		Page 34

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Contents DIAMOND-MM-48-AT Table of Contents Description DIAMOND-MM-48-AT Board Drawing O Header Pinout and PIN Description Signal Name DefinitionJ3 Analog and Digital I/O J4 Relays and Optocouplers Signal Name Definition Relay output contactsOptoisolated input contacts Base Address Jumper Position Hex Decimal Board ConfigurationBase Address Interrupt Level SelectionReserved Optocoupler PolarityAnalog Input Range Base + Write Function Read Function OverviewLSB MSB DA7 DA6 DA5 DA4 DA3 DA2 DA1 DA0 Register Map Bit AssignmentsWrite operations Read operationsDefinitions Register DefinitionsBase + Write Base + ReadBase + Read/Write A/D Channel Register AD9 AD8HIGH3 HIGH2 HIGH1 HIGH0 LOW3 LOW2 LOW1 LOW0 RELAY7 RELAY6 RELAY5 RELAY4 RELAY3 RELAY2 RELAY1 RELAY0 Base + Read/Write Digital I/O Configuration RegisterBase + Read/Write Relay Control Port DIR3 DIR2 DIR1 DIR0DEDGE3 DEDGE2 DEDGE1 DEDGE0 DIO3 DIO2 DIO1 DIO0 DIO3 DIO2 DIO1 DIO0Base + Read Digital I/O Data and Edge Status OEN3 OEN2 OEN1 OEN0 POL3 POL2 POL1 POL0Daupdt DACH2 DACH1 DACH0 Base + Write Channel and Control RegisterOEDGE3 OEDGE2 OEDGE1 OEDGE0 OPTO3 OPTO2 OPTO1 OPTO0 Base + Write Command Register Dapre Daprld Reset Fiforst AdstartBase + Read Status Register POL ADCH3 ADCH2 ADCH1 ADCH0Base + Write Configuration Register CKSEL1 CKFRQ1 CKFRQ0 Scnint Clken ClkselBase + Read Configuration & Status Register Adbusy Dabusy CKSEL1 CKFRQ1 CKFRQ0 Scnint Clken ClkselBase + Read Fifo Status Register Base + Write Fifo Control RegisterFifoth Fifoen Scanen OVF Fifoth Fifoen ScanenBase + Write Interrupt Control Register Clrt Clrd Clro Clra Tinte Dinte Ointe AinteBase + Read Interrupt Status Register Tint Dint Oint Aint Tinte Dinte Ointe AinteBase + Read/Write Counter/Timer D15 Base + Read/Write Counter/Timer D7Base + Read/Write Counter/Timer D23 Ctrno Latch Gtdis Gten Ctdis Cten Load CLR Base + Write Counter/Timer Control RegisterCtrno Base + Read/Write Eeprom / TrimDAC Data Register Base + Read/Write Eeprom / TrimDAC Address RegisterBase + Read Calibration Status Register Base + Write Eeprom Access Key RegisterBase + Write Calibration Control Register Base + Read Fpga Revision CodeInput Ranges Analog Input Ranges and ResolutionResolution Single Ended and Differential InputsPerforming AN A/D Conversion Trigger an A/D conversion on the current channel LSB = readbase MSB = readbase+1 Data = MSB * 256 + LSBInput voltage = A/D value / 32768 * Full-scale voltage Clken Clksel D SCAN, FIFO, and Interrupt OperationTrigger Conversion or ScanFifoen Fifoth Scanen Fifo OperationInterrupt Operation Fifoen =Operation Table Guidelines for Selecting Fifo Use Fifoen and FifothAinte Fifoen Scanen Analog Output Overview Generating AN Analog Output 12.2 A/D calibration Autocalibration OperationReference Voltages 12.3 D/A CalibrationDigital I/O Operation Procedure for enabling interrupts on selected edges Optocoupler OperationEdge detection assumes OENn = 1 to enable edge detection Polarity and logic readbackRelay Operation Counter 0 A/D Sample Control COUNTER/TIMER OperationCounter 1 Counting/Totalizing Functions Command Sequences CounterCounter Outpbase+15,0x01 Outpbase+15,0x81 Autocalibration SpecificationsGeneral