DI Errata

The latest product enhancement (PCN HC030703 DI enhancement) introduced to all

MARC4 products during 2003, leads, under some conditions, to an unforeseen and

unwanted behavior. The circuit may not process interrupts correctly. All above men-

tioned MARC4 products are affected.

Description

If a DI command is immediately followed by a CALL or SCALL command and an inter-

rupt meets this DI command, this interrupt is kept in the interrupt active register

permanently despite a correct RTI execution. Even if the EI command in the inter-

rupted program has been executed, this bit in the interrupt active register stays set

and disables the execution of any interrupt of the same or lower priority. Only an inter-

rupt with a higher priority or a reset is able to solve this blocking status.

If the command following the DI is a NOP, the interrupt active register usually is

cleared correctly after an RTI and executing interrupts then continues normally.

MARC4 4-bit

Microcontrollers

ATAM893S

ATAM894P

ATAR092/892P

ATAR090/890H

ATAR080F

ATA6020N

ATAR510F

ATAR862N3/4/8

Errata Sheet

Rev. 4813A–4BMCU–06/04