NEC PD754144 - Manual (Page 139)

CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
139 User’s Manual U10676EJ3V0UM
[Timer set time] (cycle) is calculated by dividing [contents of modulo register + 1] by [count pulse (CP)
frequency] selected by the mode register.
T (sec) = = (n+1) (resolution)
where,
T (sec): Timer set time (seconds)
f
CP
(Hz): CP frequency (Hz)
n: Contents of modulo register (n ≠ 0)
Once the timer has been set, interrupt request flag IRQTn is set at the set time interval of the timer.
Table 6-7 shows the resolution of each count pulse of the timer counter and the longest set time (time when FFH
is set to the modulo register).
Table 6-7. Resolution and Longest Set Time (8-Bit Timer Counter Mode) (1/3)
(TM10 = 0, TM11 = 0, TM20 = 0, TM21 = 0)
(a) µPD754244: at 6.0 MHz
8-bit timer counter (channel 0)
Mode Register 8-bit Timer Counter (Channel 0)
TM06 TM05 TM04 Resolution Longest set time
1 0 0 171
µs
43.7 ms
1 0 1 42.7 µs 10.9 ms
1 1 0 10.7
µs
2.73 ms
1 1 1 2.67 µs 683 µs
8-bit timer counter (channel 1)
Mode Register 8-bit Timer Counter (Channel 1)
TM16 TM15 TM14 Resolution Longest set time
0 1 1 5.33 µs 1.37 ms
1 0 0 683 µs 175 ms
1 0 1 171 µs 43.7 ms
1 1 0 42.7 µs 10.9 ms
1 1 1 10.7 µs 2.73 ms
n +1
f CP
.