psd4235g2 STMicroelectronics, psd4235g2 Datasheet - Page 88

• Manufacturer Part Number: psd4235g2
• Description: Flash In-system Programmable Isp Peripherals For 16-bit Mcus 5v Supply
• Manufacturer: STMicroelectronics

I/O ports
20.14
20.15
20.16
20.17
20.18
20.19
88/129
Port Data registers
The Port Data registers, shown in
data from the ports.
and MCU access for each register type. The registers are described next.
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 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 Mask macrocell register bits
are not set, writing to the macrocell loads data to the macrocell flip-flops (see
Macrocell and I/O
Mask macrocell register
Each Mask macrocell register bit corresponds to an output macrocell (OMC) flip-flop. When
the Mask macrocell 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.
Input macrocells (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 18.6: Input macrocells
Table 47.
Data In
Data Out
Output macrocell
Register Name
Port Data registers
port).
Table 47
A, B, C, D, E, F,
G
A, B, C, D, E, F,
G
A, B
shows the register name, the ports having each register type,
(IMC)).
Port
Table
47, are used by the MCU to write data to or read
READ - input on pin
WRITE/READ
READ - outputs of macrocells
WRITE - loading macrocells Flip-flop
MCU Access
Figure 13:
PSD4235G2