C165_96 Datasheet, PDF (109/283 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontrollers

Parallel Ports / C165/C163
The port structure of the Port 3 pins depends on their alternate function (see figures below).
When the on-chip peripheral associated with a Port 3 pin is configured to use the alternate input
function, it reads the input latch, which represents the state of the pin, via the line labeled “Alternate
Data Input”. Port 3 pins with alternate input functions are:
T2IN, T3IN, T4IN, T3EUD and CAPIN.
When the on-chip peripheral associated with a Port 3 pin is configured to use the alternate output
function, its “Alternate Data Output” line is ANDed with the port output latch line. When using these
alternate functions, the user must set the direction of the port line to output (DP3.y=1) and must set
the port output latch (P3.y=1). Otherwise the pin is in its high-impedance state (when configured as
input) or the pin is stuck at '0' (when the port output latch is cleared). When the alternate output
functions are not used, the “Alternate Data Output” line is in its inactive state, which is a high level
('1'). Port 3 pins with alternate output functions are:
T6OUT, T3OUT, TxD0 and CLKOUT.
When the on-chip peripheral associated with a Port 3 pin is configured to use both the alternate
input and output function, the descriptions above apply to the respective current operating mode.
The direction must be set accordingly. Port 3 pins with alternate input/output functions are:
MTSR, MRST, RxD0 and SCLK.
Note: Enabling the CLKOUT function automatically enables the P3.15 output driver. Setting bit
DP3.15=’1’ is not required.
Semiconductor Group
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