This is in reference to article titled “Critical Sections” the FreeRTOS web page titled “Running the RTOS on a ARM Cortex-M Core” located at
There it says:
“BASEPRI is a bit mask. Setting BASEPRI to a value masks all interrupts that have a priority at and (logically) below that value. It is therefore not possible to use BASEPRI to mask interrupts that have a priority of 0.”
Thee second statement does not seem to follow precisely from the first. The first part of this paragraph says “priority AT” and the second part says “not possible . . . to mask interrupts that have a priority of 0.” However, the article says priority 0 cannot be masked , so saying “priority at” seems inconsistent. If the article is consistent, a priority of 0 is a logical priority and therefore the highest priority, which is not supposed to be maskable. Is it that the first part the paragraph is true except for logical priority 0?
Please clarify or correct that paragraph for me.