Real Time Devices AD1200 User Manual page 42

BA + 4: PPI Port A - Digital VO (Read/Write)
Transfers the 8-bit Port A digital input and digital output data between the board and an external device. A read
transfers data from the external device, ttrrough V2,andino PPI Port A; a write transfers the written data from Port
A through P2 to an extemal device.
BA + 5: PPI Port B - ChanneVBoard Functions Select (ReadAVrite)
Programs the analog input channel, and enables the IRQ and external trigger. Reading this register shows you
the current settings.
IRQ Enabl
0 = IRQ disabled
1 = IRQ enabled
D7 D6 D5 D4
D3 D2 D1 DO
Enable
Analog lnput
Channel Select
0000 = channel 1
BA + 6: PPI Port C - Digital UO (Read/Write)
Transfers the two 4-bit Port C digital input and digital output data groups @ort C Upper and Port C Lower)
between the board and an extemal device. A read transfers data frrom the external device, through Y2, andino PPI
Port C; a write Sansfers the written daa from Port C through P2 to an external device.
BA + 7: 8255 PPI Control Word (Write Only)
When bit 7 of this word is set to l, a write programs ttre PPI configuration. The PPI must be programmed so
that Port B is a Mode 0 output port, as shown below (X = don't care).
External Trigger Enable
0 = Disabled
1 = Enabled
Mode Set
1 = active
0001 = channel 2
0010 = channel 3
0 0 1 1 = c h a n n e l 4
01 00 = channel 5
0101 = channel 6
01 10 = channel 7
0 1 1 1 = c h a n n e l S
1000 = channel 9
1001 = channel 10
1 0 1 0 = c h a n n e l l l
1 0 1 1 = c h a n n e l 1 2
1 1 0 0 = c h a n n e l
1 3
1 101 = channel 14
1 1 1 0 = c h a n n e l 1 5
1 1 1 1 = c h a n n e l 1 6
t C Lower
output
input
D7 D6 D5 D4
D3 D2 D1 DO
| |
PortC
I I
o = o u l
| |
1 = i n p
I
I
Port B
I
o = outPut
|
1 = inpur
I
Mode SelEct
0 = m o d e 0
1 = m o d e 1
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is:
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I
I
I
I
rde Seler
= mode t
= mode
= mode I
>t
Port A
0 = output
1 = input
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fr"rl
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