on the nrf5340 DK i want to put the external flash into it lowest power state before i go to deep sleep

[weightwatcherphil]

i have a custom board with the nrf5340 which uses the same external flash as the one on the nrf5340 DK board.  Before i put the processor into deep sleep with regulators off i want to know what i should do to the external flash to have it draw the minimum amount of power.

should I program the CS to off.  should i program the reset pin to put the part into reset?

should i send the chip a command to go to low power state ?

if so what should i set the CS and reset pins to ?

thanks

phil

[Simonr]

Hi

A very similar question was asked in this DevZone ticket, where my colleague Dejan has a lengthy discussion with another user, so please give it a read and let me know if anything is unclear.

In summary, the generic way forward would be to finish up any data transfers, uninit and power down the MX25 to a low power mode, and then set the CS pin to off to make sure it's off. Then you put the nRF5340 device into a low power mode by ending any other threads that might be running.

Best regards,

Simon

[weightwatcherphil]

right now i am looking at using the SPI channel to command the MX25 to go to the deep power down mode.  I found this on the data sheet.

thanks

phil

[Susheel Nuguru]

Hi, 

Sorry for delayed answer, Simon went on vacation and this thread fell into the invisible cracks.

weightwatcherphil said:

right now i am looking at using the SPI channel to command the MX25 to go to the deep power down mode

I do not think we have resources to help or debug commands specific SPI commands for a specific sensor. The other ticket has established that the SPI and also QSPI works to access MX25xx. 

If the default driver of MX25xx does not support it already with the custom commands to make the chip go to low power, then you need to ask the Zephyr community or the sensor vendor to help with this.

[weightwatcherphil]

i have found a command in the data sheet to put it in low power mode.  I also have a power profiler II now to let me measure if the command works.

thanks

phil

[Susheel Nuguru]

Awesome. Can you please write little details about the low power command you found so that it helps other forum members who stumble on the same issue?

And thanks a ton for caring to coming back here and writing about the solution.