nR7002DK I2C Logic Level

[Michael Zeng]

Quick Question: Is the I2C logic level of the nRF7002DK 3.3V or 1.8V? 

I have found this table in the nRF5340 specifications: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf5340%2Fgpio.html&cp=4_0_0_6_12_5_0&anchor=unique_1679281215

But am having trouble finding exactly what VDD is (and whether it's 3.3V or 1.8V) in the datasheet.

Thanks,

Michael

[ovrebekk]

Hi Michael

The GPIO voltage for the nRF5340 on the nRF7002-DK is 1.8V. 

Best regards
Torbjørn

[Michael Zeng]

Quick followup question: if 3.3V is supplied to the nrf5340's VDD pin, the GPIO voltage would then be 3.3V, right?

If I design a custom PCB and supply 3.3V to the nrf5340's VDD pin, are there any nuances to be aware of? I think I would likely have to also supply 3.3V to the IOVDD of the nrf7002, right (since the nrf5340 and nrf7002 communicate using QSPI)?

[ovrebekk]

Hi 

If you design your own PCB you can choose between using the nRF5340 either in normal voltage mode or in high voltage mode. 

In normal voltage mode the GPIO voltage will be identical to the supply voltage, yes, and the valid range of supply voltages is in the 1.7-3.6V range. 

In high voltage mode the GPIO voltage will be regulated down from the supply voltage, and can be set independently (as long as it is lower). In this mode the supply range is 2.5-5.5V, and the GPIO voltage range is 1.8-3.3V. 

For more information please refer to the REGULATORS chapter in the documentation. 

Michael Zeng said:

If I design a custom PCB and supply 3.3V to the nrf5340's VDD pin, are there any nuances to be aware of? I think I would likely have to also supply 3.3V to the IOVDD of the nrf7002, right (since the nrf5340 and nrf7002 communicate using QSPI)?

IOVDD on the nRF7002 should be the same as the GPIO voltage of the nRF5340, yes. 

There is one issue to be aware of if you want to use a higher voltages on the QSPI interface, and that is Errata 136 for the nRF5340. Essentially the QSPI interface will not work at 96MHz if the voltage is higher than 2.0V, and if you want to run higher voltages you might need to use the SPI interface instead of QSPI. 

Best regards
Torbjørn

[Michael Zeng]

Got it, thank you. I can also avoid errata 136 by running the QSPI at a different clock frequency right?

Do you know what default clock frequency the QSPI operates at for the nrf7002dk? If I create a build configuration for nrf7002dk_nrf5340_cpuapp, I see this in the devicetree: 

Does this mean the QSPI clock frequency is 24 MHz? So powering the nrf5340 with 3.3V shouldn't be an issue then?

If I did want to change the clock frequency, would I simply need to just change the value of sck-frequency in the devicetree?

I would like to run code on the PCB I am designing that requires as little modification from the wifi scan sample as possible.

[ovrebekk]

Hi 

Michael Zeng said:

Got it, thank you. I can also avoid errata 136 by running the QSPI at a different clock frequency right?

That should be possible, yes. 

Michael Zeng said:

Does this mean the QSPI clock frequency is 24 MHz? So powering the nrf5340 with 3.3V shouldn't be an issue then?

I must admit I wasn't aware of this, but it seems 24 MHz is the default frequency, yes. As such you should be able to run the communication at 3.3V if you want. This hasn't been tested extensively on our side though, so I can't guarantee that there will be no side effects. 

Michael Zeng said:

If I did want to change the clock frequency, would I simply need to just change the value of sck-frequency in the devicetree?

Yes, that should be sufficient. 

Best regards
Torbjørn