SH7751 Group, SH7751R Group
Section 19 Interrupt Controller (INTC)
R01UH0457EJ0301 Rev. 3.01
Page 791 of 1128
Sep 24, 2013
19.6
Usage Notes
19.6.1
NMI Interrupts (SH7751 Only)
When multiple NMI interrupts are input to the NMI pin within a set period of time (which is
dependent on the internal state of the CPU and the external bus state), subsequent interrupts may
not be accepted.
Note that this problem does not occur when sufficient time*
1
is provided between NMI interrupt
inputs or with non-NMI interrupts such as IRL interrupts.
Workarounds:
Any of the following methods may be used to avoid the above problem.
(1) Allow sufficient time between NMI interrupt inputs, as described in note 1, below.
Note that it may not be possible to assure the above interval between NMI interrupt inputs if
hazard is input to NMI, and that this may cause the device to malfunction. Design the external
circuits so that no hazard is input via NMI.*
2
(2) Do not use NMI interrupts. Use IRL interrupts instead.
(3) Workaround using software
The above problem can be avoided by inserting the following lines of code*
3
*
4
into the NMI
exception handling routine.
Notes: 1. If SR.BL is cleared to 0 so that one or more instructions may be executed between the
handling of two NMI interrupts.
2. When changing the level of the NMI input, ensure that the high and low durations are
at least 5 CKIO cycles. Also ensure that no noise pulses occur before or after level
changes.
3. If the NMI exception handling routine contains code that changes the value of the
SR.BL bit, the code listed below should be inserted before the point at which the
change is made.
4. Registers R0 to R3 in the code sample can be changed to any general register. Also, the
necessary register save and restore instructions should be inserted before and after the
code listed below, as appropriate.
Содержание SH7751 Group
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Страница 226: ...Section 5 Exceptions SH7751 Group SH7751R Group Page 172 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
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Страница 388: ...Section 12 Timer Unit TMU SH7751 Group SH7751R Group Page 334 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 800: ...Section 17 Smart Card Interface SH7751 Group SH7751R Group Page 746 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 848: ...Section 19 Interrupt Controller INTC SH7751 Group SH7751R Group Page 794 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 876: ...Section 20 User Break Controller UBC SH7751 Group SH7751R Group Page 822 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1036: ...Section 22 PCI Controller PCIC SH7751 Group SH7751R Group Page 982 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1152: ...Appendix C Mode Pin Settings SH7751 Group SH7751R Group Page 1098 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
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Страница 1186: ... SH7751 Group SH7751R Group User s Manual Hardware R01UH0457EJ0301 Previous Number REJ09B0370 0400 ...