Omega ISA- BUS MULTI-FUNCTIONAL BOARD OME-A822PG - Manual (Page 29)

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:
z
A/D data register BASE+4/BASE+5 stores the A/D conversion data (sec. 2.4.2)
z A/D gain control register BASE+9 selects the gain (sec. 2.4.6)
z A/D multiplexer control register BASE+A selects the analog input
channel (sec. 2.4.7)
z A/D mode control register BASE+B selects the trigger type and transfer
type (sec. 2.4.8)
z A/D software trigger control register is BASE+C (sec. 2.4.9)
z JP3 selects single-ended or differential input (sec. 2.3.3)
z JP4 selects internal/external trigger (sec. 2.3.4)
z JP5 selects the IRQ level (sec. 2.3.5)
z JP6 selects the internal/external clock for counter0 (sec. 2.3.6)
z JP7 and JP8 selects the DMA channel (sec. 2.3.7)
z There are 3 trigger types : software, pacer, external trigger (sec.
2.4.8)
z There are 3 transfer types : polling, interrupt, DMA (sec. 2.4.8)
The block diagram is given below:
JP3 Base+C
OME-A-822PGL/PGH
Base+B JP4 JP5
JP7
JP8
Base+A Base+9 Trigger
Logic CPU Transfer
Logic
Memory
Buffer 12 bits
A/D Gain
control 16/8 to 1
Multi-
plexer CN3
OME-A-822PGL/PGH Hardware Manual ---- 27