Epson S1C63666 Technical Manual page 146

CHAPTER 5: SUMMARY OF NOTES
Input port
When input ports are changed from high to low by pull-down resistors, the fall of the waveform is
delayed on account of the time constant of the pull-down 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 calcu-
lated by the following expression.
10 × C × R
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
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 is selected for the FOUT signal frequency, it is necessary to control the OSC3 oscillation
OSC3
circuit before output.
Refer to Section 4.4, "Oscillation Circuit", for the control and notes.
I/O port
When in the input mode, I/O ports are changed from high to low by pull-down resistor, the fall of the
waveform is delayed on account of the time constant of the pull-down 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
LCD driver
Because at initial reset, the contents of display memory are undefined and LC3–LC0 (LCD contrast) is
set to 0000B, 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
Be sure to read timer data in the order of low-order data (TM0–TM3) then high-order data (TM4–
TM7).
Stopwatch timer
(1) The interrupt factor flag should be reset after resetting the stopwatch timer.
(2) Be sure to data reading in the order of SWD0–3 → SWD4–7 → SWD8–11.
(3) When data that is held by a LAP input is read, read the capture buffer renewal flag CRNWF after
reading the SWD8–11 and check whether the data has been renewed or not.
(4) When performing a processing such as a LAP input preceding with 1 Hz interrupt processing, read
the LAP data carry-up request flag LCURF before processing and check whether carry-up is needed or
not.
Programmable timer
(1) When reading counter data, be sure to read the low-order 4 bits (PTDx0–PTDx3) first. Furthermore,
the high-order 4 bits (PTDx4–PTDx7) should be read within 0.73 msec (when f
reading the low-order 4 bits (PTDx0–PTDx3).
(2) The programmable timer actually enters RUN/STOP status in synchronization with the falling edge
of the input clock after writing to the PTRUNx register. Consequently, when "0" is written to the
PTRUNx register, the timer enters STOP status at the point where the counter is decremented (-1).
136
C: terminal capacitance 5 pF + parasitic capacitance ? pF
R: pull-down resistance 375 kΩ (Max.)
C: terminal capacitance 5 pF + parasitic capacitance ? pF
R: pull-down resistance 375 kΩ (Max.)
EPSON
) level the same as the DC output if "0" is
SS
is 32.768 kHz) of
OSC1
S1C63666 TECHNICAL MANUAL