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RL78/G15 CHAPTER 4 PORT FUNCTIONS

R01UH0959EJ0110 Rev.1.10 Page 116 of 765

Mar 7, 2023

4.5 Register Settings When Using Alternate Function

4.5.1 Basic concept when using alternate function

In the beginning, for a pin also assigned to be used for analog input, use the port mode control registers 0, 2 (PMC0,

PMC2) to specify whether to use the pin for analog input or digital input/output.

Figure 4-7 shows the basic configuration of an output circuit for pins used for digital input/output. The output of the

output latch for the port and the output of the alternate SAU function are input to an AND gate. The output of the AND

gate is input to an OR gate. The output of an alternate function other than SAU (TAU, clock/buzzer output, IICA, etc.) is

connected to the other input pin of the OR gate. When such kind of pins are used as the port function or an alternate

function, the unused alternate function must not hinder the output of the function to be used. An idea of basic settings for

this kind of case is shown in Table 4-6.

Figure 4-7. Basic Configuration of Output Circuit for Pins

Output latch

(Pmn)

POM register

(POMmn)

Alternate function

(SAU)

Alternate function

(other than SAU)

Pmn/Alternate function

To input circuit

POM

P-ch

N-ch

Note 1

Note 3

PM register

(PMmn)

PORT

Note 2

Internal bus

Note 1. When there is no POM register, this signal should be considered to be low level (0).

Note 2. When there is no alternate function, this signal should be considered to be high level (1).

Note 3. When there is no alternate function, this signal should be considered to be low level (0).

Remark m: Port number (m = 0, 2, 4, 12, 13); n: Bit number (n = 0 to 7)

Renesas RL78/G15 User Manual

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