st72324bk STMicroelectronics, st72324bk Datasheet - Page 29

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

ST72323 ST72323L
6
6.1
6.2
Note:
Interrupts
Introduction
The ST7 enhanced interrupt management provides the following features:
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This interrupt management is based on:
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This enhanced interrupt controller guarantees full upward compatibility with the standard
(not nested) ST7 interrupt controller.
Masking and processing flow
The interrupt masking is managed by the I1 and I0 bits of the CC register and the ISPRx
registers which give the interrupt software priority level of each interrupt vector (see
Table
When an interrupt request has to be serviced:
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The interrupt service routine should end with the IRET instruction which causes the
contents of the saved registers to be recovered from the stack.
As a consequence of the IRET instruction, the I1 and I0 bits will be restored from the stack
and the program in the previous level will resume.
Hardware interrupts
Software interrupt (TRAP)
Nested or concurrent interrupt management with flexible interrupt priority and level
management:
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Bit 5 and bit 3 of the CPU CC register (I1:0),
Interrupt software priority registers (ISPRx),
Fixed interrupt vector addresses located at the high addresses of the memory map
(FFE0h to FFFFh) sorted by hardware priority order.
Normal processing is suspended at the end of the current instruction execution.
The PC, X, A and CC registers are saved onto the stack.
I1 and I0 bits of CC register are set according to the corresponding values in the ISPRx
registers of the serviced interrupt vector.
The PC is then loaded with the interrupt vector of the interrupt to service and the first
instruction of the interrupt service routine is fetched (refer to “Interrupt Mapping” table
for vector addresses).
5). The processing flow is shown in
Up to 4 software programmable nesting levels
Up to 16 interrupt vectors fixed by hardware
2 non maskable events: RESET, TRAP
Figure 13
Interrupts
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