Mitsubishi Electric M32170F3VFP, User Manual

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10
10-12 Ver.0.10
MULTIJUNCTION TIMERS
10.2 Common Units of Multijunction Timer
10.2.2 Prescaler Unit
The prescalers PRS0-5 are an 8-bit counter, which generates clocks supplied to each timer (TOP,
TIO, TMS, TML, TID, TOD, and TOM) from the divide-by-2 frequency of the internal peripheral
clock (10.0 MHz when the internal peripheral clock = 20 MHz).
The values of prescaler registers are initialized to H'00 when reset. Also, when you rewrite the set
value of any prescaler register, the device starts operating with the new value simultaneously when
the prescaler underflows.
Values H'00 to H'FF can be set in the counter registers of prescalers. The prescalers' divide-by
ratios are given by the equation below.
1
Prescaler divide-by ratio = —————
Prescaler set value + 1
■
Prescaler Register 0 (PRS0) <Address: H'0080 0202>
■
Prescaler Register 1 (PRS1) <Address: H'0080 0203>
■
Prescaler Register 2 (PRS2) <Address: H'0080 0204>
■
Prescaler Register 3 (PRS3) <Address: H'0080 07D0>
■
Prescaler Register 4 (PRS4) <Address: H'0080 0BD0>
■
Prescaler Register 5 (PRS5) <Address: H'0080 0CD0>
D0 1 2 3 4 5 6 D7
( D8 9 10 11 12 13 14 D15 )
PRS0 - PRS5
<When reset : H'00>
D Bit Name Function R W
0 - 7 PRS0, 2 - 5 Sets the prescaler's divide-by value
8 - 15 PRS1
Prescaler Registers 0-2 start counting after reset removal. Prescaler Registers 3-5 each are
activated by setting the TID0 Control & Prescaler 3 Enable Register, TID1 Control & Prescaler 4
Enable Register, and TID2 Control & Prescaler 5 Enable Register to 1 (= count start), upon which
they reload the prescaler register value and start counting. For details, refer to Section 10.7, "TID
(Input-related 16-bit Timer)."