Operation Of 8-Bit Timers H0 And H1; Operation As Interval Timer - NEC 78K0/KD1 Series User Manual

8.4 Operation of 8-Bit Timers H0 and H1

8.4.1 Operation as interval timer

When 8-bit timer counter Hn and compare register 0n (CMP0n) match, an interrupt request signal (INTTMHn) is
generated and 8-bit timer counter Hn is cleared to 00H.
Compare register 1n (CMP1n) is not used in interval timer mode. Since a match of 8-bit timer counter Hn and the
CMP1n register is not detected even if the CMP1n register is set, timer output is not affected.
(1) Usage
Generates the INTTMHn signal repeatedly at the same interval.
<1> Set each register.
(i) Setting timer H mode register n (TMHMDn)
TMHEn CKSn2
TMHMDn 0 0/1
(ii) CMP0n register setting
• Compare value (N)
<2> Count operation starts when TMHEn = 1.
<3> When the values of 8-bit timer counter Hn and the CMP0n register match, the INTTMHn signal is generated
and 8-bit timer counter Hn is cleared to 00H.
<4> Subsequently, the INTTMHn signal is generated at the same interval. To stop the count operation, set
TMHEn to 0.
Remark n = 0, 1
186
CHAPTER 8 8-BIT TIMERS H0 AND H1
Figure 8-6. Register Setting in Interval Timer Mode
CKSn1 CKSn0 TMMDn1 TMMDn0 TOLEVn
0/1 0/1 0
Interval time = (N +1)/f
CNT
Preliminary User's Manual U16315EJ1V0UD
TOENn
0 0/1 0/1
Timer output setting
Timer output level inversion setting
Interval timer mode setting
Count clock (f
Count operation stopped
) selection
CNT