cortex M4 writes to flash

rbenv.3 · ‎2019-03-22

With Cortex M0+ (BLE) running, how Cortex M4 writes data on flash ?

The reference manual says during flash writes all acess are denied.

Christophe Arnal · ‎2019-03-22

Hello,

When a flash write procedure is started, the flash is busy and no CPU ( either CM4 or CM0+) can fetch code or read data from the flash.

You may write data in flash on the CM4 side at any time. As the CM0+ may write data in flash as well, you shall first get Semaphore2 before writing in the flash and release it once you do not need anymore to write in the flash so that the CM0+ may write when needed its own data.

You may check as an example the BLE_Ota application where the flash is written by the CM4 in the file otas_app.c

Regards.

View solution in original post

Christophe Arnal · ‎2019-03-22

Hello,

When a flash write procedure is started, the flash is busy and no CPU ( either CM4 or CM0+) can fetch code or read data from the flash.

You may write data in flash on the CM4 side at any time. As the CM0+ may write data in flash as well, you shall first get Semaphore2 before writing in the flash and release it once you do not need anymore to write in the flash so that the CM0+ may write when needed its own data.

You may check as an example the BLE_Ota application where the flash is written by the CM4 in the file otas_app.c

Regards.

rbenv.3 · ‎2019-03-22

Understood. Any write only stalls the entire flash.

Waiting publication of the semaphore allocation from the BLE side

Thank you Christophe