About sd_flash_write function - 0xFF evaluation & delay time

RE: About sd_flash_write function - 0xFF evaluation & delay time

Hung Bui — Thu, 12 Jul 2018 09:21:51 GMT

This is a 3 years old case, please create a new case. We suggest you to use fstorage, and fds instead of accessing the softdevice flash API directly. Here is some examples.

RE: About sd_flash_write function - 0xFF evaluation & delay time

boston — Wed, 11 Jul 2018 20:31:52 GMT

"You should implement a check for the flash call back event (NRF_EVT_FLASH_OPERATION_ERROR, NRF_EVT_FLASH_OPERATION_SUCCESS) in the system event instead of rely on the timing."

I would like to implement this but don't know how...do you know of any examples? I actually haven't found any examples using sd_flash_write at all.

Thanks

RE: About sd_flash_write function - 0xFF evaluation & delay time

Hung Bui — Mon, 20 Jul 2015 09:12:40 GMT

@chd: You are welcome. If the answer answered your question, please mark it as correct.

RE: About sd_flash_write function - 0xFF evaluation & delay time

chd — Fri, 17 Jul 2015 15:08:32 GMT

So the max time to write a page would be around 11.8ms which is smaller than erase time. Not a big deal for my app, I guess. Anyway, thank you Hung!

RE: About sd_flash_write function - 0xFF evaluation & delay time

Hung Bui — Thu, 16 Jul 2015 11:45:56 GMT

@Chd:

No, I don't think we have that check in our code in the softdevice.
I don't have the exact amount of time for writing 0xFF, what we have is the maximum timing , which is 46.3us for writing a 32bit word from flash.
You would need to consider the blocking time by the softdevice's radio activity. So it will be 256x46.3 + blocking time. The blocking time is depend on the number of BLE packets have to be transmitted, and if there is any other activity that has higher priority that the flash operation. The erase time is also defined in the spec, which is 22.3ms. But the erase command also have to be scheduled and the scheduler is dependent on the BLE activity.

You should implement a check for the flash call back event (NRF_EVT_FLASH_OPERATION_ERROR, NRF_EVT_FLASH_OPERATION_SUCCESS) in the system event instead of rely on the timing.