Precautions - Epson S1C63003 Technical Manual

6 inTeRRuPT COnTROlleR
6.6

Precautions

• The interrupt factor flags are set when the interrupt condition is established, even if the interrupt mask registers are
set to "0."
• 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 handler routine before shifting to the interrupt enabled state.
• 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 interrupts including NMI are masked and
interrupts cannot be accepted until the other one is set.
• 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 vector jump and branch the
program to the interrupt handler from there.
• Both the OSC1 and OSC3 oscillation circuits stop oscillating when the CPU enters SLEEP mode. To prevent the
CPU from a malfunction when it resumes operating from SLEEP mode, switch the CPU clock to OSC1 before
placing the CPU into SLEEP mode.
6-8
Seiko epson Corporation
S1C63003/004/008/016 TeChniCal Manual
(Rev. 1.1)