Square-Wave Output Operation - NEC 78K0 Series User Manual

8.4.3 Square-wave output operation

A square wave with any selected frequency is output at intervals determined by the value preset to 8-bit timer
compare register 5n (CR5n).
The TO5n pin output status is inverted at intervals determined by the count value preset to CR5n by setting bit 0
(TOE5n) of 8-bit timer mode control register 5n (TMC5n) to 1. This enables a square wave with any selected
frequency to be output (duty = 50%).
Setting
<1> Set each register.
• Clear the port output latch (P17 or P33)
• TCL5n: Select the count clock.
• CR5n:
Compare value
• TMC5n: Stop the count operation, select the mode in which clear & start occurs on a match of TM5n and
CR5n.
LVS5n
1
0
Timer output enabled
(TMC5n = 00001011B or 00000111B)
<2> After TCE5n = 1 is set, the count operation starts.
<3> The timer output F/F is inverted by a match of TM5n and CR5n. After INTTM5n is generated, TM5n is
cleared to 00H.
<4> After these settings, the timer output F/F is inverted at the same interval and a square wave is output from
TO5n.
The frequency is as follows.
• Frequency = 1/2t (N + 1)
(N: 00H to FFH)
Note 8-bit timer/event counter 50: P17, PM17
8-bit timer/event counter 51: P33, PM33
Caution Do not write other values to CR5n during operation.
Remarks 1. For how to enable the INTTM5n signal interrupt, see CHAPTER 19 INTERRUPT FUNCTIONS.
2. n = 0, 1
256
CHAPTER 8 8-BIT TIMER/EVENT COUNTERS 50 AND 51
Note
and port mode register (PM17 or PM33)
LVR5n
0 Timer output F/F clear (0) (default output value of TO50 pin: low level)
1 Timer output F/F set (1) (default output value of TO5n pin: high level)
Preliminary User's Manual U17260EJ3V1UD
Timer Output F/F Status Setting
Note
to 0.