Omega Engineering OME-A8111 manual 1 A/D conversion flow, 2 A/D Conversion Trigger Modes

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2.7.1 A/D conversion flow

Then the user must decide which A/D conversion mode will be used. The software driver supports three different modes. The user can control the A/D conversion by polling mode very easily (sec. 2.4.9). It is recommended to use the software driver if using interrupt or DMA mode.

The analog input signals come from CN1.

The multiplexer can accept 8 single-ended lines into the gain control module. The gain control module also needs settling time if the gain control code changed. Because the software doesn’t monitor the settling time, the user should reserve enough settling time

if switching from one channel to the next (sec. 2.4.6).

The output of the gain control module feeds into the A/D converter. The A/D converter

needs a trigger signal to start an A/D conversion cycle. The OME-A-8111 supports software trigger or pacer trigger mode.

2.7.2A/D Conversion Trigger Modes

OME-A-8111 supports two trigger modes.

1 : Software Trigger :

Writes any value to the A/D software trigger control register, BASE+A, will initiate an A/D conversion cycle. This mode is very simple but very difficult to control the sampling rate.

2 : Pacer Trigger Mode :

The block diagram of the pacer timer is shown in section 2.6. The pacer timer can give very precise sampling rates.

OME-A-8111 Hardware Manual (ver.1.1, Jul/2003)

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Contents User’sGuide Canada MexicoBenelux Czech RepublicOME-A-8111 Table of Contents Calibration Features General DescriptionSpecifications Power ConsumptionAnalog Inputs 3 A/D ConverterDA Converter Digital I/OInterrupt Channel Programmable Timer/Counter Product Check ListApplications Hardware Configuration Board LayoutI/O Base Address Setting Default base address isJumper Setting 1 JP1 D/A Internal Reference Voltage SelectionI/O Register Address Address Read Write8254 Counter 2 A/D Input Buffer Register3 D/A Output Latch Register 4 D/I Input Buffer RegisterClear Interrupt Request 6 A/D Gain Control Register7 A/D Multiplex Control Register 8 A/D Mode Control Register SI2 SI1 SI09 A/D Software Trigger Control Register 10 D/O Output Latch Register Digital I/O CN38254 Timer/Counter CounterA/D Conversion SecIf switching from one channel to the next sec Pacer Trigger Mode1 A/D conversion flow 2 A/D Conversion Trigger ModesUsing software trigger and polling transfer 3 A/D Transfer ModesD/A Conversion Analog Input Signal Connection Signal ShieldingPin Assignment CN1 Analog input/Analog output/Connect Pin AssignmentCN2 Analog input/Analog output/Connect Pin Assignment CN3 Analog input/Analog output/Connect Pin AssignmentDaughter Board OME-CA-4002OME-DB-16P OME-DB-16RCalibration Calibration VR DescriptionDI/O Testing D/A Calibration StepsA/D Calibration Steps WARRANTY/DISCLAIMER Temperature
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