UPD78F0988AGC-8BS Renesas Electronics America, UPD78F0988AGC-8BS Datasheet - Page 161

• Manufacturer Part Number: UPD78F0988AGC-8BS
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0988AGC-8BS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

TM5n count value
7.6 Notes on 8-Bit Timer/Event Counter
(1) Error on starting timer
(2) Operation after changing value of compare register during timer count operation
(3) Reading TM5n during timer operation
Figure 7-19. Timing After Changing Values of Compare Registers During Timer Count Operation
Count clock
TM5n count value
An error of up to 1 clock occurs after the timer has been started until a match signal is generated. This is
because 8-bit timer counter 5n (TM5n: n = 0 to 2) is started asynchronously to the count clock.
Remark n = 0 to 2
If the new value of 8-bit compare register 5n (CR5n: n = 0 to 2) is less than the value of corresponding 8-bit
timer counter 5n (TM5n: n = 0 to 2), TM5n continues counting, overflows, and restarts counting from 0.
Therefore, if the new value of CR5n (M) is less than the old value (N), it is necessary to restart the timer after
changing the value of CR5n.
Caution Except when TI5n input is selected, be sure to clear TCE5n to 0 before setting the STOP mode.
Remark N > X > M
Because the count clock is stopped when TM5n is read during operation, select a count clock with a waveform
whose high-/low-level is longer than two CPU clock cycles. For example, in the case of a CPU clock (f
equal to f
Remark n = 0 to 2
CR5n
Count clock
X
n = 0 to 2
, TM5n can be read as long as the selected count clock is f
f
X
: System clock oscillation frequency
X – 1
Timer starts
N
Figure 7-18. Start Timing of 8-Bit Timer Counter
00H
CHAPTER 7 8-BIT TIMER/EVENT COUNTER
X
User’s Manual U13029EJ7V1UD
01H
M
02H
FFH
X
/4 or lower.
03H
00H
01H
04H
02H
159
CPU
)