CHAPTER 7 TIMER/COUNTER FUNCTION
156
(4) Prescaler mode register 0 (PRM0)
This register selects a count clock of the 16-bit timer (TM0) and the valid edge of TI0n input. PRM0 is set by an
8-bit memory manipulation instruction.
RESET input clears PRM0 to 00H.
Figure 7-5. Format of Prescaler Mode Register 0 (PRM0)
At reset: 00H
R/W
Address: FFFFF206H
7
6
5
4
3
2
1
0
PRM0
ES011
ES010
ES001
ES000
0
0
PRM01
PRM00
ES011
ES010
Selects Valid Edge of TI01
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
ES001
ES000
Selects Valid Edge of TI00
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
PRM01
PRM00
Selects Count Clock
0
0
f
xx
/2 (8.5 MHz: at f
xx
= 17 MHz)
0
1
f
xx
/16 (1.06 MHz: at f
xx
= 17 MHz)
1
0
Watch timer output (INTWTI)
1
1
Valid edge of TI00
Cautions 1.
When selecting the valid edge of TI0n as the count clock, do not specify the valid edge of
TI0n to clear and start the timer and as a capture trigger.
2.
Set PRM0n after halting the timer operation.
3.
When the TI0n pin is high level immediately after system reset, the rising edge is
detected immediately after the valid edge of the TI0n pin is specified as the rising edge
or both edges and the 16-bit timer (TM0) operation is enabled. Be careful when the TI0n
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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