CHAPTER 8 8-BIT TIMERS H0 AND H1
Preliminary User’s Manual U16315EJ1V0UD
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8.4.2 Operation as PWM pulse generator
In PWM mode, a pulse with an arbitrary duty and arbitrary cycle can be output.
8-bit timer compare register 0n (CMP0n) controls the cycle of timer output (TOHn). Rewriting the CMP0n register
during timer operation is prohibited.
8-bit timer compare register 1n (CMP1n) controls the duty of timer output (TOHn). Rewriting the CMP1n register
during timer operation is possible.
The operation in PWM mode is as follows.
TOHn output becomes active and 8-bit timer counter Hn is cleared to 0 when 8-bit timer counter Hn and the
CMP0n register match after the timer count is started. TOHn output becomes inactive when 8-bit timer counter Hn
and the CMP1n register match.
(1) Usage
In PWM mode, a pulse for which an arbitrary duty and arbitrary cycle can be set is output.
<1>
Set each register.
Figure 8-8. Register Setting in PWM Pulse Generator Mode
(i)
Setting timer H mode register n (TMHMDn)
0
0/1
0/1
0/1
1
0
0/1
1
TMMDn0 TOLEVn
TOENn
CKSn1
CKSn2
TMHEn
TMHMDn
CKSn0
TMMDn1
Timer output enabled
Timer output level inversion setting
PWM mode selection
Count clock (f
CNT
) selection
Count operation stopped
(ii) Setting CMP0n register
•
Compare value (N): Cycle setting
(iii) Setting CMP1n register
•
Compare value (M): Duty setting
Remarks 1.
n = 0, 1
2.
00H
≤
CMP1n (M) < CMP0n (N) < FFH
<2>
The count operation starts when TMHEn = 1.
<3>
The CMP0n register is the compare register that is to be compared first after counter operation is enabled.
When the values of 8-bit timer counter Hn and the CMP0n register match, 8-bit timer counter Hn is cleared,
an interrupt request signal (INTTMHn) is generated, and TOHn output becomes active. At the same time,
the compare register to be compared with 8-bit timer counter Hn is changed from the CMP0n register to the
CMP1n register.