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CHAPTER 17 DTP/EXTERNAL INTERRUPTS
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Setting procedure
To use the DTP/external interrupt, set each register by using the following procedure:
1. Set the input port to the general-purpose I/O port, which is shared with the terminal to be used as
external interrupt input.
2. Set the external interrupt factor select register (EISSR) corresponding to the DTP/external interrupt
channel to be used.
3. Set the interrupt request enable bit corresponding to the DTP/external interrupt channel to be used to 0
(ENIR1:EN).
4. Use the detection condition select bit corresponding to the DTP/external interrupt pin to be used to set
the edge or level to be detected (ELVR1: LA, LB).
5. Set the interrupt request flag bit corresponding to the DTP/external interrupt channel to be used to 0
(EIRR1: ER).
6. Set the interrupt request enable bit corresponding to the DTP/external interrupt channel to be used to 1
(ENIR1: EN).
Note that concurrent writing with 16-bit data is available in 5 and 6.
• When setting the registers for the DTP/external interrupt, the external interrupt request must be disabled
in advance (ENIR1: EN = 0).
• When enabling the DTP/external interrupt request (ENIR1:EN = 1), the corresponding DTP/external
interrupt request flag bit must be cleared in advance (EIRR1:ER = 0). These actions prevent the
mistaken interrupt request from occurring when setting the register.
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Selecting of DTP or external interrupt function
Whether the DTP function or the external interrupt function is executed depends on the setting of the
EI
2
OS enable bit in the corresponding interrupt control register (ICR:ISE).
If the ISE bit is set to "1", the EI
2
OS is enabled.
If the ISE bit is set to "0", the EI
2
OS is disabled and the external interrupt function is executed.
Notes:
• All interrupt requests assigned to one interrupt control register have the same interrupt levels (IL2 to
IL0).
• If two or more interrupt requests are assigned to one interrupt control register and the EI
2
OS is used in
one of them, other interrupt requests cannot be used.
• Enabling unequipped terminals causes a false operation. First set the EISSR and then set each of the
registers when DTP/external interrupt is used.