Renesas rl78 User Manual

RL78/G1A

CHAPTER 4 PORT FUNCTIONS

R01UH0305EJ0200 Rev.2.00

118

Jul 04, 2013

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 ADPC register or port mode control

Figure 4-11 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, RTC, clock/buzzer output, IICA,

etc.) is connected to the other input pin of the OR gate. When such kind of pins are used by 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 4-5.

Figure 4-11. Basic Configuration of Output Circuit for Pins

Notes 1.

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

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

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

Remark m: Port number (m = 0 to 7, 12 to 15); n: Bit number (n = 0 to 7)

PORT

Internal bus

Note 1

Note 2

Note 3

PM register

(PMmn)

Output latch

(Pmn)

Alternate

function (SAU)

Alternate function

(other than SAU)

POM

POM register

(POMmn)

Pmn/
Alternate function

P-ch

N-ch

To input circuit

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