38C3 datasheet(42/224 Pages) RENESAS

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38C3 Group User’s Manual

HARDWARE

1-27

Fig. 23 Timing chart of timer A PWM, IGBT output modes

sNotes on Timer A

(1) Write order to timer A

• In the timer and pulse output modes, write to the timer A register

(low-order) first and to the timer A register (high-order) next. Do not

write to only one side.

• In the IGBT and PWM modes, write to the registers as follows:

the compare register (high- and low-order)

the timer A register (low-order)

the timer A register (high-order).

It is possible to use whichever order to write to the compare register

(high- and low-order). However, write both the compare register and

the timer A register at the same time.

(2) Read order to timer A

• In all modes, read to the timer A register (high-order) first and to the

timer A register (low-order) next. Read order to the compare regis-

ter is not specified.

• If reading to the timer A register during write operation or writing to

it during read operation, normal operation will not be performed.

(3) Write to timer A

• When writing a value to the timer A address to write to the latch

only, the value is set into the reload latch and the timer is updated

at the next underflow. Normally, when writing a value to the timer A

address, the value is set into the timer and the timer latch at the

same time, because they are written at the same time.

When writing to the latch only, if the write timing to the high-order

reload latch and the underflow timing are almost the same, an ex-

pected value may be set in the high-order counter.

• Do not switch the timer count source during timer count operation.

Stop the timer count before switching it. Additionally, when perform-

ing write to the latch and the timer at the same time, the timer count

value may change large.

(4) Set of timer A mode register

Set the write control bit to “1” (write to the latch only) when setting the

IGBT and PWM modes.

Output waveform simultaneously reflects the contents of both regis-

ters at the next underflow after writing to the timer A register (high-

order).

(5) Output control function of timer A

When using the output control function (INT1 and INT2) in the IGBT

mode, set the levels of INT1 and INT2 to “H” in the falling edge active

or to “L” in the rising edge active before switching to the IGBT mode.

FUNCTIONAL DESCRIPTION

Timer A count

source

Timer A

PWM mode

IGBT output mode

(n-m+1) ! ts

m ! ts

(n+1) ! ts

Note: PWM waveform (duty : (n-m+1)/(n+1) and period : (n+1) ! ts) is output.

n : setting value of Timer A

m : setting value of compare register

ts : period of Timer A count source

38C3 Datasheet(PDF) 42 Page - Renesas Technology Corp

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