UPD78F0988AGC-8BS Renesas Electronics America, UPD78F0988AGC-8BS Datasheet - Page 278

• Manufacturer Part Number: UPD78F0988AGC-8BS
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0988AGC-8BS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

14.4.4 Multiple interrupt servicing
interrupt). When an interrupt request is acknowledged, the other interrupts are disabled (IE = 0). To enable
multiple interrupts, therefore, the IE flag must be set to 1 by executing the EI instruction during interrupt servicing
and interrupts must be enabled.
programmable priority. An interrupt has two types of priorities: a default priority and a programmable priority.
Multiple interrupts are controlled by the programmable priority.
being serviced is generated, the interrupt is acknowledged as multiple interrupt. If an interrupt request with a priority
lower than that of the interrupt currently being serviced is generated, the interrupt is not acknowledged as multiple
interrupt.
interrupt is held pending. After the servicing of the current interrupt is complete, and after one instruction of
the main servicing has been executed, the pending interrupt is acknowledged.
examples.
276
Acknowledging another interrupt request while one interrupt is being serviced is called multiple interrupts.
Multiple interrupts are not generated unless interrupt requests are enabled (IE = 1) (except the non-maskable
Even if interrupt requests are enabled, some multiple interrupts are not acknowledged due to control by the
In the EI status, if an interrupt request having the same as or higher priority than that of the interrupt currently
If interrupts are disabled, or if a multiple interrupt is not acknowledged because it has a low priority, the
Multiple interrupts are not acknowledged while the non-maskable interrupt is being serviced.
Table 14-4 shows interrupt requests enabled for multiple interrupts. Figure 14-14 shows multiple interrupt
Table 14-4. Interrupt Requests Enabled for Multiple Interrupt During Interrupt Servicing
Maskable interrupt
Non-maskable interrupt
Software interrupt
Remarks 1.
Servicing Interrupt
2. ISP and IE are flags included in PSW.
3.
: Multiple interrupt enabled.
: Multiple interrupt disabled.
PR is flag included in PR0L, PR0H, and PR1L.
ISP = 0: Interrupt with higher priority is serviced.
ISP = 1: Interrupt request is not acknowledged or interrupt with lower priority is being
IE = 0:
IE = 1:
Multiple Interrupt
PR = 0: Higher priority level
PR = 1: Lower priority level
ISP = 0
ISP = 1
Request
CHAPTER 14 INTERRUPT FUNCTIONS
serviced.
Acknowledging interrupt request is disabled.
Acknowledging interrupt request is enabled.
User’s Manual U13029EJ7V1UD
Interrupt Request
Non-Maskable
IE = 1
Maskable Interrupt Request
PR = 0
IE = 0
IE = 1
PR = 1
IE = 0