My question is, is there a difference between SPI programming (interfaces, configuration etc) between the original arduino uno R3 boards and the cheaper 'compatible' ones.
The one node with 'compatible' Uno is able to transmit data but not receive. I have had same observations by changing the RF modules and changing the cheaper UNO boards (I have many of them). These cheaper boards are not new as I have been working with them for a few months now without any problem.
The same setup (code,RF modules and connection) works perfectly fine when using two genuine UNOs. Which leaves me to wonder why.
One difference that I can find is that the cheaper UNOs that I have, have a 12Mhz Oscillator on the board as against 16 MHz on the original.
I have also checked the continuity of the SPI pins from ICSP header to digital pins 11,12 and 13.
Furthermore, I stumbled across this article which says
On Arduino UNO boards SPI pins are connected with some digital pins. While using modem you most remember that these digital pins won’t be available.
- Does the aforementioned have anything to do with my setup?
I am so confused without any hint whatsoever that might be causing the problem. Pardon me if my problem statement is not very clear. SPI is the only thing I can doubt as of now.
PS: the codes that I am using are copies from here and compiles without error