
338
CHAPTER 13 REMOTE CONTROL GENERATOR (6-BIT PPG)
Figure 13.5-1 Changing Settings during Operation (Remote Control)
Direct comparisons are performed between the 6-bit counter of the remote control generator
and the "H" pulse width setting bits (RCR1: HSC5 to HSC0), and between the counter and the
cycle setting bits (RCR2: SCL5 to SCL0). Therefore, if a setting is reduced in mid-count, the
cycle time (t1) may be long until the counter overflows in the worst case and the takes effect in
the next cycle. Similarly, the "H" state pulse width (t2) may be long in the worst case until the
next end-of-cycle match is detected.
r Errors
Activating the counter by program is not synchronized with the start of counting-up using the
selected count clock. Therefore, the time from activating the counter until a match with the "H"
pulse comparison value and Cycle comparison value are detected may be shorter than the
theoretical time by a maximum of one cycle of the count clock.
Figure 13.5-2 "Error during activating Operation (Remote Control)" shows the error that occurs
on starting counter operation.
Figure 13.5-2 Error during activating Operation (Remote Control)
*3
*1
*2
00H
*1
3FH
Counter count
Overflow
Cycle setting value
(RCR2: SCL)
"H" pulse width setting value
(RCR1: HSC)
RCO output
waveform
One
cycle
*1: Since the current count in the counter is less than the new setting, the new setting takes effect for the
current cycle.
*2: Since cycle is changed to a value less than the current count, the counter counts all the way to
counter overflow and takes effect in the next cycle (in the worst case).
*3: Since the new "H" pulse width setting is less that the current count, the pulse width match is not
detected until the next cycle (in the worst case).
*4: The length of the t
1
and t2 is depended on when the new cycle setting value and "H" pulse
width setting value. It wll vary from case to case.
t1*4
t2*4
l)
One cycle
Counter activate
Error Cycle for 00H
Counter value
Count clock
00H
01H
02H
03H
04H