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7.11
Port A
7.11.1
Overview
Port A is an 8-bit input/output port that is also used for output (TP
timing pattern controller (TPC), input and output (TIOCB
TIOCA
, TCLKD, TCLKC, TCLKB, TCLKA) by the 16-bit timer, clock input (TCLKD, TCLKC,
0
TCLKB, TCLKA) to the 8-bit timer, and address output (A
transition leaves port A as an input port, except that in modes 3 and 4, one pin is always used for
A
output. See table 7.19 to 7.21 for the selection of pin functions.
20
Usage of pins for TPC, 16-bit timer, and 8-bit timer input and output is described in the sections
on those modules. For output of address bits A
Bus Release Control Register (BRCR). Pins not assigned to any of these functions are available
for generic input/output. Figure 7.10 shows the pin configuration of port A.
Pins in port A can drive one TTL load and a 30-pF capacitive load. They can also drive a
darlington transistor pair. Port A has Schmitt-trigger inputs.
200
to TP
7
, TIOCA
2
2
to A
). A reset or hardware standby
23
20
to A
in modes 3, 4, and 5, see section 6.2.4,
23
20
) from the programmable
0
, TIOCB
, TIOCA
, TIOCB
1
1
,
0
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