Operating the XtraDrive Using XtraWare
The Interrupt_mask variable is reset to zero each time the program is
started (by the RUN command or the auto start switch). Therefore, the
Interrupt_mask must be set each time.
4.11.6.3. Interrupt_pending
The Interrupt_pending variable indicates which interrupts are to be handled.
The value of a bit in Interrupt_pending is only set to 1 (indicating that the
interrupt is to be handled) if both of the following conditions are met:
♦ The interrupt event has occurred and the corresponding bit in
Interrupt_request has been set to 1.
♦ You have enabled the interrupt in the mask register, Interrupt_mask.
Once the corresponding interrupt service routine has been completed, the
bit in the variable is reset to 0.
Interrupt_pending is a read-only variable, and its values thus cannot be
changed by the user.
4.11.6.4. Example of Interrupt Variable Functioning
Interrupt_mask:
To specify that only interrupts 3 and 7 be handled, should their conditions
be met, bits 3 and 7 in the variable Interrupt_mask must be set to 1 and all
other bits must be set to 0, as shown:
Bit#
7 6 5 4 3
2
1
0
Setting 1 0 0 0 1
0
0
0
Variable value: Interrupt_mask = 136
Interrupt_request:
If the interrupt conditions for interrupts 1, 3 and 4 are met, then bits 1,3
and 4 in the variable Interrupt_request will be set to 1 and all other bits will
be set to 0.
Bit# 7 6 5
4 3
2
1
0
Setting 0 0 0 1 1
0
1
0
Variable value: Interrupt_request = 26
XtraWare User Manual 79
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