
DocID13284 Rev 2
143/564
UM0404
Parallel ports
DP1L (F104h / 82h)
ESFR
Reset Value: - - 00h
DP1H (F106h / 83h)
ESFR
Reset Value: - - 00h
6.3.1 Alternate
functions of PORT1
When a de-multiplexed external bus is enabled, PORT1 is used as address bus.
Note that de-multiplexed bus modes use PORT1 as a 16-bit port. Otherwise all 16 port lines
can be used for general purpose I/O. The upper four pins of PORT1 (P1H.7...P1H.4) are
also capture input lines for the CAPCOM2 unit (CC27-24 I).
As all other capture inputs, the capture input functions of pins P1H.7...P1H.4 can also be
used as external interrupt inputs with a sample rate of eight CPU clock cycles.
As a side effect, the capture input capability of these lines can also be used in the address
bus mode. Hereby changes of the upper address lines could be detected and trigger an
interrupt request in order to perform some special service routines. External capture signals
can only be applied if no address output is selected for PORT1.
During external accesses in de-multiplexed bus modes PORT1 outputs the 16-bit intra-
segment address as an alternate output function.
During external accesses in multiplexed bus modes, when no BUSCON register selects a
de-multiplexed bus mode, PORT1 is not used and is available for general purpose I/O.
The lower 8 bits of PORT1 (P1L) also serve as input lines for the eight additional analog
channels for the A/D converter: General purpose I/O or external memory bus functions must
be properly disabled in order to avoid data conflicts when using P1L pins as analog input
lines. General purpose I/O and analog input functionality can be mixed without any problem
along P1L pins, that is some of P1L pins can be used as general purpose I/O, others as
analog input lines; it is also possible (if meaningful at application level) to use the same pin
as analog input and general purpose I/O line.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
DP1L.
7
DP1L.
6
DP1L.
5
DP1L.
4
DP1L.
3
DP1L.
2
DP1L.
1
DP1L.
0
RW
RW
RW
RW
RW
RW
RW
RW
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
DP1H
.7
DP1H
.6
DP1H
.5
DP1H
.4
DP1H
.3
DP1H
.2
DP1H
.1
DP1H
.0
RW
RW
RW
RW
RW
RW
RW
RW
Bit
Function
DP1X.y
Port direction register DP1H or DP1L bit y
’0’: Port line P1X.y is an input (high-impedance).
’1’: Port line P1X.y is an output.