spi nrf52/ 5v arduino logic levels

[paul_tanner]

Hi,

I had some erratic results when I hook these devices via SPI, using a level shifter (e.g. TXB0104) to protect the nRF52. When I look at the schematic for the nRF52-DK I see that there is no level shifting on the pins intended for Arduino shields. Do I read this correctly? If so I can presumably connect the devices directly which would eliminate any problems cause by the level shifters.

[ovrebekk]

Hi Paul

The nRF52-DK is not 5V tolerant, but many Arduino shields will work fine with 3-3.3V signals.

In other words I would not connect your device directly, but rather try to figure out what is wrong with the level shifter connection.
Do you have a scope available so you can see what is going on on the lines?
What SPI frequency are you running at?

As a side note, the nRF52840 has a high voltage mode that makes it 5V tolerant, but this device is not yet in production (we have a preview DK available for development).

Best regards
Torbjørn

[paul_tanner]

Thx @Torbjørn

I have confirmed that the electrical connection works fine with level shifters. I had some issues with the firmware on the Arduino-style slave device. I lowered the clock rate and made sure that the slave can respond rapidly enough using interrupts and pre-buffered data. Now it works fine.