A/D Conversion - Omega ISA- BUS MULTI-FUNCTIONAL BOARD OME-A822PG Hardware Manual

2.7 A/D Conversion

This section explains how to perform A/D conversions. The A/D conversion
can be triggered 3 ways, by software trigger, by pacer trigger or by
external trigger to the A/D converter. At the end of A/D conversion, it is
possible to transfer data by 3 ways, those are polling , interrupt and DMA.
Before using the A/D conversion functions, the user should be aware of the
following issues:
A/D data register BASE+4/BASE+5 stores the A/D conversion data (sec. 2.4.2)
A/D gain control register BASE+9 selects the gain (sec. 2.4.6)
A/D multiplexer control register BASE+A selects the analog input
channel (sec. 2.4.7)
A/D mode control register BASE+B selects the trigger type and transfer
type (sec. 2.4.8)
A/D software trigger control register is BASE+C (sec. 2.4.9)
JP3 selects single-ended or differential input (sec. 2.3.3)
JP4 selects internal/external trigger (sec. 2.3.4)
JP5 selects the IRQ level (sec. 2.3.5)
JP6 selects the internal/external clock for counter0 (sec. 2.3.6)
JP7 and JP8 selects the DMA channel (sec. 2.3.7)
There are 3 trigger types : software, pacer, external trigger (sec.
2.4.8)
There are 3 transfer types : polling, interrupt, DMA (sec. 2.4.8)
The block diagram is given below:
CN3 16/8 to 1
Multi-
plexer
Base+A
JP3
OME-A-822PGL/PGH
Gain
control
Base+9
Base+C
OME-A-822PGL/PGH Hardware Manual ---- 27
12 bits
A/D Buffer
Trigger Transfer
Logic Logic
JP4 Base+B JP5
JP7
JP8
Memory
CPU