
S1C621A0 TECHNICAL SOFTWARE
EPSON
II-31
CHAPTER 2: PERIPHERAL CIRCUITS (Remote-control LEDs)
Detailed description
of REM control regis-
ters—Part 1 (opera-
tion under software
timer control)
REMC
The REMC register turns the REM circuit on or off. Set-
ting the register to 1 causes the OSC3 clock to be intro-
duced into the carrier generator circuit, thus turning the
REM circuit on. If the register is set to 0, the REM circuit
turns off; this synchronizes with the reference cycle (
τ).
OSC3 must be turned off at least the time
τ after the
REMC register has been set to 0. The REMC register can
be set to 1 only with OSC3 on.
At Initial reset, the REMC register is set to 1 and initial-
ized by hardware. This dictates that at least 32 machine
cycles be required before the REMC register can be set to
0.
If you need no REM output, hold the REMC register at 0
to save power.
RCDIV and RCDUTY
The REM carrier is generated by dividing the OSC3
frequency. The RCDIV and RCDUTY registers are used to
determine a division ratio and a duty ratio. Once set,
these registers generate carriers with the set division
ratio and duty ratio. Except for initialization the REMC
register should be set at 0 when the RCDIV and RCDUTY
registers are set. (Setting RCDIV and RCDUTY with the
REMC at 1 will cause a malfunction.)
REMSO
The REMSO register is used when a pulse width is deter-
mined by software, A carrier is on at the REM pin while
the REMSO register is set at 1. Thus the pulse width of
the REM output is determined by the timing of when data
1 or 0 is set in the REMSO register.
If you use hardware to determine a pulse width, the
REMSO register must be fixed at 0.
These four registers are used to determine REM output
under software timer control.