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Pin
P9
/TxD
1
1
P9
/TxD
0
0
7.7
Port A
7.7.1
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 tables 7.12 to 7.14 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
Release Control Register (BRCR). Pins not assigned to any of these functions are available for
generic input/output. Figure 7.6 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.
156
Pin Functions and Selection Method
Bit TE in SCR of SCI1, bit SMIF in SCMR, and bit P9
function as follows.
SMIF
TE
P9
DDR
1
Pin function
Note: * Functions as the TxD
which the pin is driven, and another in which the pin is at high-
impedance.
Bit TE in SCR of SCI0, bit SMIF in SCMR, and bit P9
function as follows.
SMIF
TE
P9
DDR
0
Pin function
Note: * Functions as the TxD
which the pin is driven, and another in which the pin is at high-
impedance.
0
0
0
1
P9
input
P9
output
1
1
output pin, but there are two states: one in
1
0
0
0
1
P9
input
P9
output
0
0
output pin, but there are two states: one in
0
, TIOCA
2
to A
23
to A
in modes 3 and 4, see section 6.2.4, Bus
23
20
DDR select the pin
1
1
—
TxD
output TxD
1
DDR select the pin
0
1
—
TxD
output TxD
0
to TP
) from the programmable
7
0
, TIOCB
, TIOCA
2
1
). A reset or hardware standby
20
1
—
—
output*
1
1
—
—
output*
0
, TIOCB
,
1
0
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