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ST18952

ISPR: Interrupt stack pointer register

(Address = 002B, Reset = 0000h, Read/Write)

Note:

’-’ is RESERVED (read: 0, write: don’t care)

ISPR contains the number of stacked priority levels. If the ISPR value is directly written, the

SPLi/CPL values are modified. So the ICR register content is no longer significant but the

interrupt routine procedure is not affected. After reset, ISPR default value is 0

ISR: Interrupt status register

(Address = 002C, Reset = 0000h, Read/Write)

Note:

‘-’ is RESERVED (read: 0, write: don’t care)

An interrupt pending (IPE) bit is associated with each interrupt input. IPE is set when the

interrupt request is recorded and is reset when the interrupt request is acknowledged (ITACK

falling edge).

When the user does not want to acknowledge any of the pending interrupt requests, the IPE

flag of the CCR register must first be reset and then the ISR register set to “0000”.

When only some pending interrupt requests need to be acknowledged, the IPE bits of the other

interrupt inputs must be reset.

When the IPE bit is set by a direct register write an interrupt request will be generated

irrespective of the state of the ITRQ pin.

When the mask (IM) bit is set, the corresponding IPE bit is reset.

876543

210

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ISP(2:0)

Bit

Function

ISPR

Number of stacked priority levels (0, 1, 2 or 3)

9876

3210

IPE7 IPE6 IPE5 IPE4 IPE3 IPE2 IPE1 IPE0

Bit

Function

IPE

Interrupt pending bit

0: Reset when interrupt request is acknowledged (default)

1: Set when interrupt request is recorded

ST18952 Datasheet(PDF) 30 Page - STMicroelectronics