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.
2.7.2 A/D Conversion Trigger Modes
OME-A-8111 supports t
wo
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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