SPI bus 8Mbps - nRF52840 DK

[swip]

Hello,

Using Spi bus with frequency = 4Mbps give me this deformed signals (clock and miso) and when I push it to 8 Mbps I am not able to get the correct values.

Obviously, I have checked when using freq=125Kbps and the signal is fine and I've got the correct values.

Is it not possible to use the maximum frequency for spi transfer with the nRF52840 chip ? Do I need to add some capacitor/resistor to improve the signal ?

Thank you in advance, Swip

[Stian Røed Hafskjold]

How do you connect the SPI slave, and how long are the lines? You might need to reduce the capacitance between master and slave. Also, the scope probes themselves can introduce quite a bit of capacitance to the lines. What is the capacitance rating on the probes you are using? You should use 1:10 probes.

You can also try to configure the GPIOs to use high drive, H0H1. infocenter.nordicsemi.com/.../gpio.html