[NRF52840] QSPI external MX25R6435F flash, write operation must wait end of DMA before being read

[alexisS]

Greetings,

Based on your librairies/examples, I can succesfully write and read data from an external flash (MX25R6435F) using QSPI with DMA.

I'm using a custom board with the NRF52840.

However after a write operation I must wait the end of DMA to preform a reading operation otherwise this reading is corrupted !

Do you have any hints ?

Thank you.

[Håkon Alseth]

Hi,

 

Compared to normal SPI, QSPI is not full duplex, so you'll have to wait until the operation is finished before triggering a new one, as stated in the STATUS register (field READY):

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/qspi.html?cp=2_0_0_5_18_9_21#register.STATUS

 

Best regards,

Håkon

[alexisS]

Thanks for your reply,

I already wait thanks to nrfx_qspi_mem_busy_check() and I also try to wait some ms ...

[Håkon Alseth]

The _mem_busy_check() function polls the external memory IC to see if it is ready to take a new write command, but the STATUS register checks to see if the NRF_QSPI still has a transaction clocking out on the QSPI lines. Both should be checked.

 

Best regards,

Håkon