NEC V850E/MS1 UPD703100, User Manual

Page: 263 / 449

CHAPTER 9 TIMER/COUNTER FUNCTION (REAL-TIME PULSE UNIT)
User’s Manual U12688EJ4V0UM00
263
9.4.2 Count clock selection
The count clock input to Timer 1 is either internal or external, and can be selected by the ETI1n bit in the TMC1n
register (n = 0 to 5).
Caution Do not change the count clock during timer operation.
(1) Internal count clock (ETI1n bit = 0)
An internal count clock can be selected from among 6 possible clock rates,
φ
/2,
φ
/4,
φ
/8,
φ
/16,
φ
/32, or
φ
/64,
by the setting of the PRS1n1, PRS1n0, and PRM1n1 bits of the TMC1n register.
PRS1n1 PRS1n0 PRM1n1 Internal Count Clock
0 0 0
φ
/2
0 0 1
φ
/4
0 1 0
φ
/8
0 1 1
φ
/16
1 0 0
φ
/16
1 0 1
φ
/32
1 1 0
φ
/32
1 1 1
φ
/64
Remark n = 0 to 5
(2) External count clock (ETI1n bit = 1)
This counts the signals input to the TI1n pin. At this time, Timer 1 can be operated as an event counter.
The TI1n active edge can be set by the TES1n1 and TES1n0 bits of the TUM1n register.
TES1n1 TES1n0 Active Edge
0 0 Rising edge
0 1 Falling edge
1 0 RFU (reserved)
1 1 Both the rising and falling edges
Remark n = 0 to 5