R28 datasheet(69/473 Pages) RENESAS

69 / 473 page

R8C/28 Group, R8C/29 Group

7. Programmable I/O Ports

Rev.2.10

Sep 26, 2008

Page 50 of 441

REJ09B0279-0210

Programmable I/O Ports

There are 13 programmable Input/Output ports (I/O ports) P1, P3_3 to P3_5, P3_7, and P4_5. Also, P4_6 and P4_7

can be used as input-only ports if the XIN clock oscillation circuit and XCIN clock oscillation circuit(1) is not used, and

the P4_2 can be used as an input-only port if the A/D converter is not used.

Table 7.1 lists an Overview of Programmable I/O Ports.

NOTE:

1. The XCIN clock oscillation circuit cannot be used for J, K version.

NOTES:

1. In input mode, whether an internal pull-up resistor is connected or not can be selected by registers

PUR0 and PUR1.

2. When the A/D converter is not used, this port can be used as the input-only port.

3. When the XIN clock oscillation circuit and XCIN clock oscillation circuit (for N, D version only) is not

used, these ports can be used as the input-only ports.

7.1

Functions of Programmable I/O Ports

The PDi_j (j = 0 to 7) bit in the PDi (i = 1, 3, 4) register controls I/O of the ports P1, P3_3 to P3_5, P3_7, and P4_5.

The Pi register consists of a port latch to hold output data and a circuit to read pin states.

Figures 7.1 to 7.4 show the Configurations of Programmable I/O Ports. Table 7.2 lists the Functions of

Programmable I/O Ports. Also, Figure 7.6 shows the PDi (i = 1, 3, 4) Register. Figure 7.7 shows the Pi (i = 1, 3, 4)

7.10 shows Registers PUR0 and PUR1, and Figure 7.11 shows the P1DRR Register.

i = 1, 3, 4, j = 0 to 7

NOTE:

1. Nothing is assigned to bits PD3_0 to PD3_2, PD3_6, PD4_0 to PD4_4, PD4_6, and PD4_7.

Table 7.1

Overview of Programmable I/O Ports

Ports

I/O

Type of Output

I/O Setting

Internal Pull-Up Resister

I/O

CMOS3 State

Set per bit

Set every 4 bits(1)

P3_3 to P3_5, P3_7

I/O

CMOS3 State

Set per bit

Set every 1 bit, 3 bits(1)

P4_5

I/O

CMOS3 State

Set per bit

Set every bit(1)

P4_2(2)

P4_6, P4_7(3)

(No output function)

None

Table 7.2

Functions of Programmable I/O Ports

Operation When

Accessing

Pi Register

Value of PDi_j Bit in PDi Register(1)

When PDi_j Bit is Set to 0 (Input Mode)

When PDi_j Bit is Set to 1 (Output Mode)

Reading

Read pin input level

Read the port latch

Writing

Write to the port latch

Write to the port latch. The value written to

the port latch is output from the pin.

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