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CHAPTER 7 TIMER/COUNTER FUNCTION
157
(5) Prescaler mode register 1 (PRM1)
This register selects a count clock of the 16-bit timer (TM1) and the valid edge of TI1n input. PRM1 is set by an
8-bit memory manipulation instruction.
RESET input clears PRM1 to 00H.
Figure 7-6. Format of Prescaler Mode Register 1 (PRM1)
At reset: 00H
R/W
Address: FFFFF216H
7
6
5
4
3
2
1
0
PRM1
ES111
ES110
ES101
ES100
0
0
PRM11
PRM10
ES111
ES110
Selects Valid Edge of TI11
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
ES101
ES100
Selects Valid Edge of TI10
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
PRM11
PRM10
Selects Count Clock
0
0
f
xx
/2 (8.5 MHz: at f
xx
= 17 MHz)
0
1
f
xx
/4 (4.25 MHz: at f
xx
= 17 MHz)
1
0
f
xx
/16 (1.06 MHz: at f
xx
= 17 MHz)
1
1
Valid edge of TI10
Cautions 1.
When selecting the valid edge of TI1n as the count clock, do not specify the valid edge of
TI1n to clear and start the timer and as a capture trigger.
2.
Set PRM1n after halting the timer operation.
3.
When the TI1n pin is high level immediately after system reset, the rising edge is
detected immediately after the valid edge of the TI1n pin is specified as the rising edge
or both edges and the 16-bit timer (TM1) operation is enabled. Be careful when the TI1n
pin is pulled-up. However, the rising edge is not detected when the operation is enebled
again after the operation has been halted.
Summary of Contents for V850/SA1 mPD703015
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