7702 datasheet(113/217 Pages) RENESAS

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TIMER A

7702/7703 Group User’s Manual

5–25

5.4 Event counter mode

(1) Switching between up-count and down-count

The up-down register (address 4416) or the input signal from the TAiOUT pin is used to switch the up-

count from and to the down-count. This switching is performed by the up-down bit when the up-down

switching factor select bit (bit 4 at addresses 5616 to 5A16) is “0,” and by the input signal from the

TAiOUT pin when the up-down switching factor select bit is “1.”

When switching the up-count/down-count, this switching is actually performed when the count source’s

next valid edge is input.

qSwitching by up-down bit

The counter down-counts when the up-down bit is “0,” and up-counts when the up-down bit is “1.”

Figure 5.4.5 shows the structure of the up-down register.

qSwitching by TAiOUT pin’s input signal

The counter down-counts when the TAiOUT pin’s input signal is at “L” level, and up-counts when the

TAiOUT pin’s input signal is at “H” level.

When using the TAiOUT pin input signal to switch the up-count/down-count, set the port P5 and P6

direction registers’ bits which correspond to the TAiOUT pin for the input mode.

Fig. 5.4.5 Structure of up-down register

Bit

Bit name

At reset

Functions

Up-down register (Address 4416)

Timer A4 up-down bit

Timer A3 up-down bit

Timer A2 up-down bit

Timer A1 up-down bit

Timer A0 up-down bit

Timer A2 two-phase pulse signal

processing select bit

(Note)

Timer A3 two-phase pulse signal

processing select bit

(Note)

Timer A4 two-phase pulse signal

processing select bit

(Note)

0 : Down-count

1 : Up-count

This function is valid when the

contents of the up-down register are

selected as the up-down switching

factor.

0 : Disabled Two-phase pulse signal

processing function

1 : Enabled Two-phase pulse signal

processing function

When not using the two-phase pulse

signal processing function, make

sure to set the bit to “0.”

The value is “0” at reading.

Note: Use the LDM or STA instruction when writing to bits 5 to 7.

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