Prescaler Unit - Renesas M32R/ECU Series User Manual

10

10.2.2 Prescaler Unit

The Prescalers PRS0–5 area an 8-bit counter, which generates clocks supplied to each timer (TOP, TIO, TMS,
TML, TID and TOU) from the internal peripheral clock (BCLK) divided by 2 (10 MHz when f(BCLK) = 20 MHz).
The values of prescaler registers are initialized to H'00 immediately after reset. When the set value of any
prescaler register is rewritten, the prescaler starts operating with the new value at the same time it has
underflowed.
Values H'00 to H'FF can be set in the prescaler register. The prescaler's divide-by ratio is given by the equation
below:
Prescaler divide-by ratio =
Prescaler Register 0 (PRS0)
Prescaler Register 1 (PRS1)
Prescaler Register 2 (PRS2)
Prescaler Register 3 (PRS3)
Prescaler Register 4 (PRS4)
Prescaler Register 5 (PRS5)
b0 1 2
b8 9 10
0 0 0
b Bit Name
0–7 PRS0–PRS5
(8–15) Prescaler
Prescaler Registers 0–2 start counting immediately after reset. Prescaler Registers 3–5 each are activated by
setting the TID0 Control & Prescaler 3 Enable Register, TID1 Control & Prescaler 4 Enable Register or TID2
Control & Prescaler 5 Enable Register's prescaler-n enable (PRSnEN) bit to "1" (count start), upon which the
prescaler register value is reloaded and the prescaler starts counting. For details, see Section 10.7, "TID (Input-
Related 16-Bit Timer)."
If the prescaler register is accessed for read during operation, the value written into it, not the current count, is
read out.
prescaler set value + 1
3 4 5 6
11 12 13 14
PRS0–PRS5
0 0 0 0
10.2 Common Units of Multijunction Timers
1
b7
b15
0
Function
Set the prescaler divide-by value
10-12
MULTIJUNCTION TIMERS
<Address: H'0080 0202>
<Address: H'0080 0203>
<Address: H'0080 0204>
<Address: H'0080 07D0>
<Address: H'0080 0BD0>
<Address: H'0080 0CD0>
<After reset: H'00>
32180 Group User's Manual (Rev.1.0)
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