UPD78F9222MC(T)-5A4-A NEC, UPD78F9222MC(T)-5A4-A Datasheet - Page 228

• Manufacturer Part Number: UPD78F9222MC(T)-5A4-A
• Description: 8BIT MCU, 4K FLASH, 256B RAM, 78F9222
• Manufacturer: NEC

Specifications of UPD78F9222MC(T)-5A4-A

• Controller Family/series: UPD78
• No. Of I/o's: 17
• Ram Memory Size: 256Byte
• Cpu Speed: 10MHz
• No. Of Timers: 4
• No. Of: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 4KB
• Oscillator Type: External, Internal

Before each interrupt request acknowledgment, the EI instruction is issued, the interrupt mask is released, and the
interrupt request acknowledgment enable state is set.
INTyy is not acknowledged, and multiple interrupts are not generated. The INTyy request is held pending and
acknowledged after the INTxx servicing is performed.
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During interrupt INTxx servicing, interrupt request INTyy is acknowledged, and multiple interrupts are generated.
Caution Multiple interrupts can be acknowledged even for low-priority interrupts.
Because interrupts are not enabled in interrupt INTxx servicing (the EI instruction is not issued), interrupt request
IE = 0: Interrupt request acknowledgment disabled
Example 2. Multiple interrupts are not generated because interrupts are not enabled
INTxx
INTxx
Main processing
Main processing
EI
EI
Figure 12-10. Example of Multiple Interrupts (1/2)
Example 1. Multiple interrupts are acknowledged
IE = 0
IE = 0
CHAPTER 12 INTERRUPT FUNCTIONS
User’s Manual U16898EJ5V0UD
INTyy
INTyy
INTxx servicing
IE = 0
INTxx servicing
RETI
RETI
EI
IE = 0
INTyy is held pending
INTyy servicing
RETI
INTyy servicing
RETI