Real Time Devices AD1200 User Manual page 126

82C55A
Readlng Port G Status
In Mode 0, Port C transfers data to or from the pe-
ripheraldevice. When the 82C554 is programmed to
function in Modes 1 or 2, Port C generates or ac-
cepts "hand-shaking" signals with the peripheral de-
vice. Reading the contents of Port C allows the pro-
grammer to test or verify the "status" of each pe-
ripheral device and change the program flow ac-
cordingly.
There is no special instruction to read the status in-
formation from Port C. A normal read operation of
Port C is executed to perform this function.
II{PUT CONFIGURATION
D7 D5 D5 Da D3 D2 D1 D6
G R O U P A G R O U P B
OUTPUT CONFIGURATIONS
D7 D5
D5 Da
D3 D2 D1 D6
G R O U P A G R O U P B
t/o
vo
lBFl
INTEI INTRI INTEs lBFs INTR6
Figure 17a. MODE I Status Word Format
D?
D5
D5 Da D3
D2
D 1
De
G R O U P A G R O U P B
(D€fn€d By Mode 0 or Mode I Sel€ction)
Figure 17b. iIODE 2 Status Word Format
Interrupt Enable Flaq Poeltlon
Alternate Port C Pln Slgnal (llode)
INTE B
INTE A2
INTE A1
PC2
PC4
PC6
Affie (Output Mode 1) orSTEe (lnput Mode 1)
STEa (lnput Mode 1 or Mode 2)
ffia
(Outout Mode 'l or Mode 2
Flgure 18. Interrupt Enable Flags ln ilodes 1 and 2
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