nRF52840 SPI and I2C pin mapping:

[Bima_zalan]

Hi,

i am using nRF52840 SoC and Had confusion on pin mapping for SPI (external flash) and I2C (external sensors) as below:

I found one similar query and it was said to not use the standard low freq IOs for I2C and SPI interface.So can you confirm that i can use below pins for SPI and I2C.

P0.4-> SPI_CS

P0.6-> SPI_Clk

P0.7-> SPI_MISO

P0.15-> SPI_MOSI

And P0.19-> I2C_SCL , P0.23 -> I2C_SDA

Also please let us know if there are any specific pins to be used for interrupts from external sensors, which can be considered as priority during interrupt events?

[Einar Thorsrud]

Hi,

Which pins are suited for high frequency or not depend not only on which IC you use, but also on the package. You can refer to the pin assignments table for the package you are using. Any pins marked with "low frequency I/O only" should not be used for SPI or TWI (or anything above ~ 10 kHz). The primary reason for this is that it can impact radio performance. This also means that if you know that you will not be using these pins while the radio is active there is no problem, with the exception of the NFC pins which have quite high capacitance also when configured as GPIOs, so they are never suitable for high frequency I/O.

[Bima_zalan]

Hi Einar,

Thanks for your quick answer, But are you sure that both the package QFN and WLCSP has different "Standard drive, low frequency I/O only" signals?

Bcoz i had already gone through it and found that both packages have same pins which mentions "Standard drive, low frequency I/O only" in Table 1 and Table 2 of pin assignments.

Asked this to just clear out that whether there is any package dependency or not.

Looking for your confirmation for the same.

[Einar Thorsrud]

Hi,

My answer was perhaps a bit too generic. There are some nRF52 family variants where there are differences between packages, but it does not apply to all. The point is to check the table for the variant and package you use, and then you are sure.