Slow AMBA Peripherals
13-33
GMS30C7201 Data Sheet
13.5.3 Functional description
All pins are defined as input during reset (
BnRES
LOW).
For each port there is a Data Register and a Data Direction Register. On reads, the
Data Register contains the current status of correspondent port pins, whether they are
configured as input or output. Writing to a Data Register only affects the pins that are
configured as outputs.
All PIO input pins can be used as interrupt source with enabled interrupt mask register
bit. These interrupt sources can be selected as active HIGH/LOW, EDGE/LEVEL
trigger mode.
Bits[5:0] of port B and bit[3:0] of port D are multiplexed with other functions and
regarded as multi-function pins. In order to use these multi-function pins as PIO pins,
the Multi-function Pin Selection register (PMPS) bit should be set.
13.5.4 Programmer
’
s model
PIO registers
The following user registers are provided:
P[A,B,C,D]DR
Data Register. Values written to this 8-bit read/write register will be
output on port [A,B,C,D] pins if the corresponding data direction bits
are set Low (port output). Values read from this register reflect the
external state of port [A,B,C,D] not necessarily the value written to it.
All bits are cleared by a system reset.
P[A,B,C,D]DDR
Port [A,B,C,D] Data Direction Register. Bits set in this 8-bit read/write
register will select the corresponding pin in port [A,B,C,D] to become
an input, clearing a bit sets the pin to output. All bits are set by a
EPB[7:0]
In
PADS
Port B input driver. It reflects the external state of the port. This information is
obtained when reading the PBDR register.
PBOE[7:0]
Out
PADS
Port B output enable (active LOW). Values written on PBDDR register are put
onto these lines.
PC[7:0]
Out
PADS
Port C output driver. Values written on PCDR register are put onto these lines
and driven out to the port C pins if the corresponding data direction bits are set
HIGH (PCDDR register).
EPC[7:0]
In
PADS
Port C input driver. It reflects the external state of the port. This information is
obtained when reading the PCDR register.
PCOE[7:0]
Out
PADS
Port C output enable (active LOW). Values written on PCDDR register are put
onto these lines.
PD[7:0]
Out
PADS
Port D output driver. Values written on PDDR register are put onto these lines
and driven out to the port D pins if the corresponding data direction bits are set
LOW (PDDDR register).
EPD[7:0]
In
PADS
Port D input driver. It reflects the external state of the port. This information is
obtained when reading the PDDR register.
PDOE[7:0]
Out
PADS
Port D output enable (active LOW). Values written on PDDDR register are put
onto these lines.
Name
Type
Source/
Destination
Description
Table 13-25: Specific block signal descriptions (Continued)