ST STM32WL55JC Reference Manual page 364

Hardware semaphore (HSEM)
8 Hardware semaphore (HSEM)
8.1 Introduction
The hardware semaphore block provides 16 (32-bit) register based semaphores.
The semaphores can be used to ensure synchronization between different processes
running between different cores. The HSEM provides a non blocking mechanism to lock
semaphores in an atomic way. The following functions are provided:
•
Locking a semaphore can be done in two ways:
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–
•
Interrupt generation when a semaphore is unlocked
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•
Semaphore clear protection
–
•
Global semaphore clear per COREID
8.2 Main features
The HSEM includes the following features:
•
16 (32-bit) semaphores
• 8-bit PROCID
•
4-bit COREID
•
1 interrupt line per processor
•
Lock indication
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2-step lock: by writing COREID and PROCID to the semaphore, followed by a
read check
1-step lock: by reading the COREID from the semaphore
Each semaphore may generate an interrupt on one of the interrupt lines
A semaphore is only unlocked when COREID and PROCID match
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