Carrier Generator Operation (8-Bit Timer H1 Only) - NEC 78K0 Series User Manual

9.4.3 Carrier generator operation (8-bit timer H1 only)

In the carrier generator mode, the 8-bit timer H1 is used to generate the carrier signal of an infrared remote
controller, and the 8-bit timer/event counter 51 is used to generate an infrared remote control signal (time count).
The carrier clock generated by the 8-bit timer H1 is output in the cycle set by the 8-bit timer/event counter 51.
In carrier generator mode, the output of the 8-bit timer H1 carrier pulse is controlled by the 8-bit timer/event counter
51, and the carrier pulse is output from the TOH1 output.
(1) Carrier generation
In carrier generator mode, the 8-bit timer H compare register 01 (CMP01) generates a low-level width carrier
pulse waveform and the 8-bit timer H compare register 11 (CMP11) generates a high-level width carrier pulse
waveform.
Rewriting the CMP11 register during the 8-bit timer H1 operation is possible but rewriting the CMP01 register is
prohibited.
(2) Carrier output control
Carrier output is controlled by the interrupt request signal (INTTM51) of the 8-bit timer/event counter 51 and the
NRZB1 and RMC1 bits of the 8-bit timer H carrier control register (TMCYC1). The relationship between the
outputs is shown below.
280
CHAPTER 9 8-BIT TIMERS H0 AND H1
RMC1 Bit NRZB1 Bit
0 0
0 1
1 0
1 1
Preliminary User's Manual U17260EJ3V1UD
Output
Low-level output
High-level output
Low-level output
Carrier pulse output