NEC mPD784225 Series User Manual page 191

(2) Prescaler mode registers 1 and 2 (PRM1, PRM2)
This register sets the count clock of 8-bit timer counters 1 and 2 (TM1, TM2) and the valid edge of TI1, TI2
inputs.
PRM1 and PRM2 are set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PRM1 and PRM2 to 00H.
Address: 0FF56H After reset: 00H R/W
Symbol 7
PRM1 0
Cautions 1. If writing data different than that of PRM1 is written, stop the timer beforehand.
2. Be sure to set bits 3 to 7 of PRM1 to 0.
3. When specifying the valid edge of TI1 for the count clock, set the count clock to f
below.
Remark Values in parentheses apply to operation at f
CHAPTER 9 8-BIT TIMER/EVENT COUNTERS 1, 2
Figure 9-4. Format of Prescaler Mode Register 1 (PRM1)
6 5
0 0
TCL12 TCL11 TCL10
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
User's Manual U12697EJ3V0UM
4 3 2
0 0 TCL12
Count clock selection
0 Falling edge of TI1
1 Rising edge of TI1
0 f /4 (3.13 MHz)
XX
1 f /8 (1.56 MHz)
XX
0 f /16 (781 kHz)
XX
1 f /32 (391 kHz)
XX
0 f /128 (97.6 kHz)
XX
1 f /512 (24.4 kHz)
XX
= 12.5 MHz.
XX
1 0
TCL11 TCL10
/4 or
XX
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