M16C6S_09 Datasheet, PDF (137/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
Programmable I/O Ports
Programmable I/O Ports
The programmable input/output ports (hereafter referred to simply as “I/O ports”) consist of 55 lines P1, P4
to P9 (except P85). Each port can be set for input or output every line by using a direction register, and can
also be chosen to be or not be pulled high every 4 lines. P85 is an input-only port and does not have a pull-
up resistor. There is no external connections for port P1_0 to P1_4, P1_6 to P1_7, P4_0 to P4_7, P5_0 to
P5_7, P7_2, P7_5, P7_7, P8_2, P8_6 to P8_7, P9_3 to P9_7.
Figures 1.18.1 to 1.18.4 show the I/O ports. Figure 1.18.5 shows the I/O pins.
Each pin functions as an I/O port, a peripheral function input/output.
For details on how to set peripheral functions, refer to each functional description in this manual. If any pin
is used as a peripheral function input, set the direction bit for that pin to “0” (input mode). Any pin used as an
output pin for peripheral functions is directed for output no matter how the corresponding direction bit is set.
(1) Port Pi Direction Register (PDi Register, i, 4 to 9)
Figure 1.18.6 shows the direction registers.
This register selects whether the I/O port is to be used for input or output. The bits in this register corre-
spond one for one to each port.
No direction register bit for P85 is available.
(2) Port Pi Register (Pi Register, i = 1, 4 to 9)
Figure 1.18.7 show the Pi registers.
Data input/output to and from external devices are accomplished by reading and writing to the Pi register.
The Pi register consists of a port latch to hold the input/output data and a circuit to read the pin status. For
ports set for input mode, the input level of the pin can be read by reading the corresponding Pi register,
and data can be written to the port latch by writing to the Pi register.
For ports set for output mode, the port latch can be read by reading the corresponding Pi register, and
data can be written to the port latch by writing to the Pi register. The data written to the port latch is output
from the pin. The bits in the Pi register correspond one for one to each port.
(3) Pull-up Control Register 0 to Pull-up Control Register 2 (PUR0 to PUR2 Registers)
Figure 1.18.8 shows the PUR0 to PUR2 registers.
The PUR0 to PUR2 register bits can be used to select whether or not to pull the corresponding port high
in 4 bit units. The port chosen to be pulled high has a pull-up resistor connected to it when the direction bit
is set for input mode.
(4) Port Control Register
Figure 1.18.9 shows the port control register.
When the P1 register is read after setting the PCR register’s PCR0 bit to “1”, the corresponding port latch
can be read no matter how the PD1 register is set.
Rev.5.01 Dec 10, 2009 page 137 of 201
REJ03B0014-0501