PSD854F3A-15UI View Datasheet(PDF) - STMicroelectronics
Part Name
Description
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PSD854F3A-15UI Datasheet PDF : 128 Pages
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I/O ports
PSD8XXFX
16.14
Port Data registers
The port Data registers, shown in Table 28, are used by the MCU to write data to or read
data from the ports. Table 28 shows the register name, the ports having each register type,
and MCU access for each register type. The registers are described below.
16.15
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.
16.16
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 output enable product term
is set to ’1.’ The contents of the register can also be read back by the MCU.
Output macrocells (OMC)
The CPLD Output macrocells (OMC) occupy a location in the MCU’s address space. The
MCU can read the output of the Output macrocells (OMC). If the OMC Mask register bits are
not set, writing to the macrocell loads data to the macrocell flip-flops (see Section 14:
PLDS).
16.17
OMC Mask register
Each OMC Mask register bit corresponds to an Output macrocell (OMC) flip-flop. When the
OMC Mask register bit is set to a 1, loading data into the Output macrocell (OMC) flip-flop is
blocked. The default value is 0 or unblocked.
Table 28. Port Data registers
Register name
Port
Data In
A,B,C,D
Data Out
A,B,C,D
Output macrocell
A,B,C
Mask macrocell
Input macrocell
Enable Out
A,B,C
A,B,C
A,B,C
MCU access
READ – input on pin
WRITE/READ
READ – outputs of macrocells
WRITE – loading macrocells flip-flop
WRITE/READ – prevents loading into a given
macrocell
READ – outputs of the input macrocells
READ – the output enable control of the port driver
16.18
Input macro (IMC)
The input macrocells (IMC) can be used to latch or store external inputs. The outputs of the
input macrocells (IMC) are routed to the PLD input bus, and can be read by the MCU (see
Section 14: PLDS).
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Doc ID 7833 Rev 7
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