CHAPTER 5 PORT FUNCTIONS
Page 87 of 920
5.5
Register Settings When Using Alternate Function
5.5.1
Basic concept when using alternate function
In the beginning, for a pin also assigned to be used for analog function, use the ADPC register or port mode control
register (PMCxx) to specify whether to use the pin for analog function or digital input/output.
Figure 5 - 8 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 (Timer, 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 5 - 6.
Figure 5 - 8 Basic Configuration of Output Circuit for Pins
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).
Int
er
na
l bu
s
WR
POM
WR
PORT
POM register
(POMmn)
Output latch
(Pmn)
WR
PM
PM register
(PMmn)
Alternate function
(SAU)
Alternate function
(other than SAU)
Note 1
Note 2
Note 3
N-ch
P-ch
V
SS
Pmn/
Alternate function
To input circuit
V
DD
Summary of Contents for RL78/G1H
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