9.11 Port A
9.11.1 Overview
Port A is an 8-bit input/output port that is also used for output (TP
7
to TP
0
) from the programmable
timing pattern controller (TPC), input and output (TIOCB
2
, TIOCA
2
, TIOCB
1
, TIOCA
1
, TIOCB
0
,
TIOCA
0
, TCLKD, TCLKC, TCLKB, TCLKA) by the 16-bit integrated timer unit (ITU), output
(TEND
1
, TEND
0
) from the DMA controller (DMAC), CS
4
to CS
6
output, and address output (A
23
to A
20
). A reset or hardware standby leaves port A as an input port, except that in modes 3, 4, and
6, one pin is always used for A
20
output. Usage of pins for TPC, ITU, and DMAC input and output
is described in the sections on those modules. For output of address bits A
23
to A
21
in modes 3, 4,
and 6, see section 6.2.5, Bus Release Control Register (BRCR). For output of CS
4
to CS
6
in modes
1 to 6, see section 6.3.2, Chip Select Signals. Pins not assigned to any of these functions are
available for generic input/output. Figure 9-10 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.
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