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SVD circuit
(1) To obtain a stable detection result, the SVD circuit must be on for at least 500 µsec. So, to obtain the SVD
detection result, follow the programming sequence below.
1.
Set SVDON to "1"
2.
Maintain for 500 µsec minimum
3.
Set SVDON to "0"
4.
Read SVDDT
(2) The SVD circuit should normally be turned off because SVD operation increase current consumption.
Interrupt
(1) The interrupt factor flags are set when the interrupt condition is established, even if the interrupt mask
registers are set to "0".
(2) After an interrupt occurs, the same interrupt will occur again if the interrupt enabled state (I flag = "1")
is set or the RETI instruction is executed unless the interrupt factor flag is reset. Therefore, be sure to
reset (write "1" to) the interrupt factor flag in the interrupt service routine before shifting to the interrupt
enabled state.
(3) After an initial reset, all the interrupts including NMI are masked until both the stack pointers SP1 and
SP2 are set with the software. Be sure to set the SP1 and SP2 in the initialize routine. Further, when re-
setting the stack pointer, the SP1 and SP2 must be set as a pair. When one of them is set, all the inter-
rupts including NMI are masked and interrupts cannot be accepted until the other one is set.
(4) When using the SLEEP function, set and confirm the P1(4)x input level, the flag and the registers for the
P1(4)x port, the CPU clock, and the power control according to the following procedures to be used to
enter/cancel SLEEP status before executing the SLP instruction surely.
1. LCD system voltage regulator power source switch register VCSEL="0"
Power supply voltage booster/halver boost mode On/Off register DBON="0"
(LCD system voltage regulator is driven with V
2. CPU system clock switching register CLKCHG = "0" (OSC1 CPU clock is selected)
3. Interrupt selection register SIPxx = "1" (the Pxx input port interrupt is selected)
4. Interrupt mask register EIKxx = "1" (the Pxx input port interrupt is enabled)
5. Noise rejector selection register NRSPxx = "00" (noise rejector is bypassed)
6. Reset the Pxx input interrupt factor flag register (write "1" to the IKxx register)
7. Interrupt flag (I flag) = "1" (interrupts are enabled)
8-1.Confirm the input to the P1(4)x port is surely HIGH level when the P1(4)x port interrupt polarity
select register = "1" (interrupt request signal is generated at the falling edge)
8-2.Confirm the input to the P1(4)x port is surely LOW level when the P1(4)x port interrupt polarity
select register = "0" (interrupt request signal is generated at the rising edge)
9. Execute SLP instruction
(5) The interrupt handler routine must be located within the range from "Interrupt vector address (100H–
10FH)" -7FH to +80H. If it is difficult, make a relay point within that range as the destination of the vec-
tor jump and branch the program to the interrupt handler from there.
)
DD
SIC63616-(Rev. 1.0) NO. P178
3240-0412
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