I need atleast 10 UART channels to be configured in my project. Is it possible to do it with the NRF52840. I believe because of the PPI I should be able to do this. I was thinking to configure 5 UARTs per UART peripheral since it has two.
Kindly help me out.
No, I don't think you'll be able to configure 10 UART channels using the PPI. You see, you'll have to use a combination of PPI and GPIOTE in order to configure the UART channels, so to configure one extra UART channel you'll have to use two GPIOTE channels. The GPIOTE peripheral only has 8 free channels, which means you'll only be able to configure 4 extra UART channels in addition to the 2 already available in the nRF52840, meaning a total of 6 UART channels would be the upper limit.
What if I plan to use the RX side only. Is it possible then?
Yes, that should technically be possible, but keep in mind that you'll have to use all GPIOTE channels in order to have 10 UART RX lines. This means that you won't be able to go higher than 10 lines. I don't think this has been tested though, so there are no guarantees that it will work, as the timing needs to work out between the different channels for example. I'm sure there are more factors to making this work as well, but none that come to mind at the moment.
Best of luck and regards,