S1C63454 TECHNICAL MANUAL
EPSON
93
CHAPTER 5: SUMMARY OF NOTES
Input port
When input ports are changed from low to high by pull-up resistors, the rise of the waveform is
delayed on account of the time constant of the pull-up resistor and input gate capacitance. Hence,
when fetching input ports, set an appropriate waiting time.
Particular care needs to be taken of the key scan during key matrix configuration.
Make this waiting time the amount of time or more calculated by the following expression.
10
×
C
×
R
C: terminal capacitance 5 pF + parasitic capacitance ? pF
R: pull-up resistance 330 k
Ω
Output port
(1) When using the output port (R02, R03) as the special output port, fix the data register (R02, R03) at "1"
and the high impedance control register (R02HIZ, R03HIZ) at "0" (data output).
Be aware that the output terminal is fixed at a low (V
SS
) level the same as the DC output if "0" is
written to the R02 and R03 registers when the special output has been selected.
Be aware that the output terminal shifts into high impedance status when "1" is written to the high
impedance control register (R02HIZ, R03HIZ).
(2) A hazard may occur when the FOUT signal and the TOUT signal are turned ON and OFF.
(3) When f
OSC3
is selected for the FOUT signal frequency, it is necessary to control the OSC3 oscillation
circuit before output.
Refer to Section 4.3, "Oscillation Circuit", for the control and notes.
I/O port
When in the input mode, I/O ports are changed from low to high by pull-up resistor, the rise of the
waveform is delayed on account of the time constant of the pull-up resistor and input gate capaci-
tance. Hence, when fetching input ports, set an appropriate wait time.
Particular care needs to be taken of the key scan during key matrix configuration.
Make this waiting time the amount of time or more calculated by the following expression.
10
×
C
×
R
C: terminal capacitance 5 pF + parasitic capacitance ? pF
R: pull-up resistance 330 k
Ω
LCD driver
(1) When a program that access no memory mounted area (F050H–F0FFH, F150H–F1FFH, F201H, F203H,
· · ·, F24FH) is made, the operation is not guaranteed.
(2) Because at initial reset, the contents of display memory and LC3–LC0 (LCD contrast) are undefined,
there is need to initialize by the software. Furthermore, take care of the registers LPWR and ALOFF
because these are set so that the display goes OFF.
Clock timer
(1) Be sure to read timer data in the order of low-order data (TM0–TM3) then high-order data (TM4–TM7).
(2) When the CR oscillation circuit is selected as the OSC1 oscillation circuit by mask option, the frequen-
cies and times differ from the values described in this section because the oscillation frequency will be
60 kHz (Typ.). Therefore, the clock timer can not be used for the clock function.
Stopwatch timer
(1) When data of the counter is read at run mode, perform the reading after suspending the counter once
and then set SWRUN to "1" again. Moreover, it is required that the suspension period not exceed 976
µsec (1/4 cycle of 256 Hz).
(2) When the CR oscillation circuit is selected as the OSC1 oscillation circuit by mask option, the frequen-
cies and times differ from the values described in this section because the oscillation frequency will be
60 kHz (Typ.). Therefore, this timer can not be used for the stopwatch function.
