CHAPTER 7 INTERRUPT/EXCEPTION PROCESSING FUNCTION
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7.3.3 Priorities of maskable interrupts
The V850E/MS1 provides multiple interrupt servicing whereby an interrupt is acknowledged while another interrupt
is being serviced. Multiple interrupts can be controlled by priority levels.
There are two types of priority level control: control based on the default priority levels, and control based on the
programmable priority levels which are specified by the interrupt priority level specification bit (xxPRn) of the interrupt
control register (xxICn). When two or more interrupts having the same priority level specified by the xxPRn bit are
generated at the same time, interrupts are serviced in order depending on the priority level allocated to each interrupt
request type (default priority level) beforehand. For more information, refer to Table 7-1. The programmable priority
control customizes interrupt requests into eight levels by setting the priority level specification flag.
Note that when an interrupt request is acknowledged, the ID flag of the PSW is automatically set to 1. Therefore,
when multiple interrupts are to be used, clear the ID flag to 0 beforehand (for example, by placing the EI instruction
into the interrupt service program) to set the interrupt enable mode.
Summary of Contents for V850E/MS1 UPD703100
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