32186 datasheet(246/1032 Pages) RENESAS

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INPUT/OUTPUT PORTS AND PIN FUNCTIONS

8-44

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

8.8 Notes on Input/Output Ports

• When using input/output ports in output mode

Because the value of the Port Data Register is undefined when exiting the reset state, the Port Data Register

must have its initial value set in it before the Port Direction Register can be set for output. Conversely, if the Port

Direction Register is set for output before setting data in the Port Data Register, the Port Data Register outputs

an undefined value until any data is written into it.

• When using input/output ports in intput mode

After switching from output mode to input mode in the Port Direction Register, or after setting port input enable

(PIEN0) bit to "1" (input enable), pin level can be read after 2BCLK period.

• About the port input disable function

Because the input/output ports are disabled against input upon exiting reset, they must be enabled for input by

setting the Port Input Enable (PIEN0) bit to "1" before their input functions can be used.

When disabled against input, the input/output ports are in a state equivalent to a situation where the pin has "L"

level input applied. Consequently, if a peripheral input function (uncontrolled pin) is selected for any port while

disabled against input by using the Port Operation Mode Register, the port may operate unexpectedly due to

the "L" level input on it.

• About the port peripheral function select register setting

The Port Peripheral Function Select Register can only be set when the corresponding bit of the Port Operation

Mode Register is "0."

• About the pereipheral function input when it is set to the gereral-purpose port

In the pin for both peripheral function input and general-purpose port, "H" level is entered to the peripheral

function input when it is set to the general-purpose port in the operation mode register. Therefore, when "L"

level is entered to the peripheral function input pin, edge signal is entered to the peripheral function input at

manipulating operation mode register.

8.8 Notes on Input/Output Ports

32186 Datasheet(PDF) 246 Page - Renesas Technology Corp