Omega OME-A822PG manual 8 A/D Mode Control Register

2.4.8A/D Mode Control Register

(WRITE)

Base+B : A/D Mode Control Register Format

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

X

X

X

X

X

D2

D1

D0

X=don‘t care

JP4 Select Internal Trigger

Mode Select

Trigger Type

Transfer Type

D2

D1

D0

Software Trig

Pacer Trig

Software

Interrupt

DMA

0

0

0

X

X

X

X

X

0

0

1

Select

X

Select

X

X

0

1

0

X

Select

X

X

Select

1

1

0

X

Select

Select

Select

X

X=disable

JP4 Select External Trigger

Mode Select

Trigger Type

Transfer Type

D2

D1

D0

External Trigger

Software

Interrupt

DMA

0

0

0

X

X

X

X

0

0

1

X

X

X

X

0

1

0

Select

X

X

Select

1

1

0

Select

Select

Select

X

The A/D conversion can be divided into 2 stages, trigger stage and transfer stage. The trigger stage will generate a trigger signal to the A/D converter and the transfer stage will transfer the result to the CPU.

The trigger method may be internal trigger or external trigger. The internal trigger can be software trigger or pacer trigger. The software trigger is simple to use but does not

control the sampling rate very precisely. In the software trigger mode, the program issues a software trigger command (sec 2.4.9) to initiate the A/D conversion. The program then must poll the A/D status bit until the ready bit is 0(sec 2.4.2).

The pacer trigger can control the sample rate very precisely. In the pacer trigger mode, the pacer timer (sec 2.6) will generate periodic trigger signals to the A/D converter. The converted data can be transferred to the CPU by polling or interrupt or by DMA transfer.

OME-A-822PGL/PGH Hardware Manual ---- 22