UPD6P9 datasheet(17/73 Pages) RENESAS

17 / 73 page

µPD67, 67A, 68, 68A, 69

Data Sheet U14935EJ2V1DS

3.1 KI/O Port (P0)

The KI/O port is an 8-bit I/O port for key scan output.

I/O mode is set by bit 1 of the P4 register.

If a read instruction is executed, the pin state can be read in input mode, whereas the output latch contents can

be read in output mode.

If a write instruction is executed, data can be written to the output latch regardless of input or output mode.

After reset, the port is placed in output mode and the value of the output latch (P0) becomes 1111 1111B.

The KI/O port incorporates a pull-down resistor, allowing pull-down in input mode only.

Caution When a key is double-pressed, a high-level output and a low-level output may conflict at the

KI/O port. To avoid this, the low-level output current of the KI/O port is held low. Therefore, be

careful when using the KI/O port for purposes other than key scan output.

The KI/O port is designed so that even when connected directly to VDD within the normal supply

voltage range (VDD = 2.0 to 3.6 V), no problem occurs.

Table 3-2. KI/O Port (P0)

Bit

Name

KI/O7

KI/O6

KI/O5

KI/O4

KI/O3

KI/O2

KI/O1

KI/O0

b0 to b7: When reading:

In input mode, the KI/O pin’s state is read.

In output mode, the KI/O pin’s output latch contents are read.

When writing:

Data is written to the KI/O pin’s output latch regardless of input or output mode.

3.2 KI Port/Special Ports (P1)

3.2.1 KI port (P11: bits 4 to 7 of P1)

The KI port is a 4-bit input port for key input. The pin state can be read.

The use of a pull-down resistor for the KI port can be specified in 4-bit units by software using bit 5 of the P4

Table 3-3. KI/Special Port Register (P1)

Bit

Name

KI3

KI2

KI1

KI0

S1/LED

Fixed to “1”

b1:

The state of the S2 pin is read (read only).

b2:

In input mode, state of the S0 pin is read (read only).

In OFF mode, this bit is fixed to 1.

b3:

The state of the S1/LED pin is read regardless of input/output mode (read only).

b4 to b7: The state of the KI pin is read (read only).

Caution In order to prevent malfunction, be sure to input a low level to one or more of pins KI0 to KI3

when POC is released by supply voltage rising (Can be left open. When open, leave the pull-

down resistor connected).

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