ZPSD6XX(V) Family
12-47
I/O Ports
(cont.)
Port Data Registers
The Port Data Registers, shown in Table 26, are used by the microcontroller to write or
read data to or from the ports. Table 26 shows the register name, the ports having
each register type and microcontroller access for each register. The registers are described
below.
Register Name
Port
MCU Access
Data In
A,B,C,D
Read – the input on pin
Data Out
A,B,C,D
Write/Read
Output Micro
Cell
A,B,C
Read – outputs of Micro
Cells
Write – loading Micro
Cells Flip-Flop
Read – outputs of the Input Micro
Cells
Input Micro
Cell
A,B,C
Enable Out
A,B,C
Read – the output enable control of the port driver
Table 26. Port Data Registers
Data In
Port pins are connected directly to the Data In buffer. In MCU I/O input mode, the pin input
is read through the Data In buffer.
Data Out Register
Stores output data written by the MCU in the MCU I/O output mode. The contents of the
Register are driven out to the pins if the Direction Register or the .oe product term is set to
“1”. The contents of the register can also be read back by the microcontroller.
Output Micro
Cell
The GPLD Output Micro
Cells occupy a location in the microcontroller’s address
space. The microcontroller can read the output of the Micro
Cells. Writing to the
Micro
Cell loads data to the Micro
Cell Flip-Flops. Refer to the ZPLD section for more
detail.
Input Micro
Cell
The Input Micro
Cells can be used to latch or store external inputs. The outputs of
the Input Micro
Cells are routed to the ZPLD input bus and also can be read by the
microcontroller. Refer to the ZPLD section for detailed description.
Enable Out
The Enable Out buffer allows the microcontroller to read the outputs of the “OR” gate that
is the enable input to the port output driver. A “1” indicates the driver is in output mode, a “0”
indicates the driver is in tri-state and the pin is in input mode.