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RL78/D1A User's Manual: Hardware - Renesas

RL78/D1A User's Manual: Hardware - Renesas

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Under development<br />

Preliminary document<br />

Specifications in this document are tentative and subject to change.<br />

<strong>RL78</strong>/<strong>D1A</strong> CHAPTER 4 PORT FUNCTIONS<br />

4.2.5 Port 4<br />

Port 4 is a 1-bit I/O port with an output latch. Port 1 can be set to the input mode or output mode using port mode<br />

register 4 (PM4). When the P40 pin is used as an input port, use of an on-chip pull-up resistor can be specified by pull-up<br />

resistor option register 4 (PU4).<br />

Reset signal generation sets port 0 to input mode.<br />

Figures 4-17 shows block diagrams of port 4.<br />

WRPU<br />

RD<br />

WRPORT<br />

WRPM<br />

Figure 4-17. Block Diagram of P40<br />

PU4<br />

PU40<br />

Alternate<br />

function<br />

P4<br />

Output latch<br />

(P40)<br />

PM4<br />

PM40<br />

Alternate<br />

function<br />

(TOOL0)<br />

P4: Port register 4<br />

PU4: Pull-up resistor option register 4<br />

PM4: Port mode register 4<br />

RD: Read signal<br />

WRxx: Write signal<br />

P40/TOOL0<br />

R01UH0317EJ0004 Rev. 0.04 166<br />

Feb. 22, 2013<br />

EVDD<br />

P-ch

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