CHAPTER 8 8-BIT TIMER H1
Preliminary User’s Manual U19014EJ1V0UD
201
8.4 Operation of 8-Bit Timer H1
8.4.1 Operation as interval timer/square-wave output
When 8-bit timer counter H1 and compare register 01 (CMP01) match, an interrupt request signal (INTTMH1) is
generated and 8-bit timer counter H1 is cleared to 00H.
Compare register 11 (CMP11) is not used in interval timer mode. Since a match of 8-bit timer counter H1 and the
CMP11 register is not detected even if the CMP11 register is set, timer output is not affected.
By setting bit 0 (TOENn) of timer H mode register 1 (TMHMD1) to 1, a square wave of any frequency (duty = 50%)
is output from TOH1.
Setting
<1> Set each register.
Figure 8-7. Register Setting During Interval Timer/Square-Wave Output Operation
(i) Setting timer H mode register 1 (TMHMD1)
0
0/1
0/1
0/1
0
0
0/1
0/1
TMMD10 TOLEV1
TOEN1
CKS11
CKS12
TMHE1
TMHMD1
CKS10
TMMD11
Timer output setting
Default setting of timer output level
Interval timer mode setting
Count clock (f
CNT
) selection
Count operation stopped
(ii) CMP01 register setting
The interval time is as follows if N is set as a comparison value.
•
Interval time = (N +1)/f
CNT
<2> Count operation starts when TMHE1 = 1.
<3> When the values of 8-bit timer counter H1 and the CMP01 register match, the INTTMH1 signal is generated
and 8-bit timer counter H1 is cleared to 00H.
<4> Subsequently, the INTTMH1 signal is generated at the same interval. To stop the count operation, clear
TMHE1 to 0.
Remarks 1.
For the setting of the output pin, see
8.3 (3) Port mode register 1 (PM1)
.
2.
For how to enable the INTTMH1 signal interrupt, see
CHAPTER 13 INTERRUPT FUNCTIONS
.
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