Chapter 4 Timer Functions

4-4 8-bit Timer Operation (timer 5)

4-4-1 Overview

Timer 5 is an 8-bit timer that can have fosc, fs/4, fx, or time base output as

its clock source.

When servicing an interrupt, reset the timer 5 interrupt request flag before starting timer 5.

When choosing either time base timer output or time base timer synchronized output for the timer 5 clock source, the time base must be set up.

During a count operation, be careful if the value set in TM5OC is smaller than the value of binary counter 5, since the count-up operation will continue until overflow occurs.

If fx input is selected as the clock source and the value of binary counter 5 is to be read during operation, select synchronized fx input to avoid reading data that may be incomplete during count- up transitions. However, with synchronized fx input, it is not possible to return from STOP/HALT modes.

4-4-2 Operation

Timer Operation

Settings for timer operation are listed below.

(1)Set the TM5CLRS flag of the timer 5 mode register (TM5MD) to "0."

(2)Use the TM5CK3 to 1 flags of the TM5MD register to select fosc, fs/4, fx, synchronized fx, time base timer output, or time base timer synchronized output as the clock source.

(3)Set a value in compare register 5 (TM5OC). At this time, if the TM5CLRS flag is "0," binary counter 5 will be initialized to X'00'.

(4)Binary counter 5 (TM5OC) counts upward from X'00'.

(5)When the value of binary counter 5 matches that of the TM5OC register, the timer 5 interrupt request flag is set, the binary counter is reset to X'00', and counting begins again.

If the TM5CLRS flag of the TM5MD register is set to "0," binary counter 5 will be initialized every time data in the TM5OC register is overwritten. Timer 5 interrupts are disabled in this mode. If timer 5 interrupts are to be used, the TM5CLRS flag must be reset to "1" after writing to the TM5OC register.

Timer 5 operation cannot be halted.

76 8-bit Timer Operation (timers 2, 3)

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Panasonic MN101C00 user manual bit Timer Operation timer