I had posted some questions about this project earlier this week. Arduino uno + w5100 ethernet shield + nrf24l01 transeiver.

The w5100 is running a webserver to accept GET requests and parse out the variables - Works all the time

The nrf24l01 is acting as a transmitter and sending data out to other nodes - Only works with no Ethernet code.

What doesn't work is both at the same time. With everything hooked up it parses get fine, gets the variable but I can't transmit it since the radio never seems to fire up. Remove all the ethernet code and leave just the radio code it sends fine.

Code here. http://pastebin.com/SMWC9x4F it errors at 146. Which I assume is the radio never starting since the:


does nothing.

I'm using manicbug's library.

I use the EXACT same send bits in that file to test wireless communication, it works. I only need it to transmit wirelessly when it get data from the network.


CSN -> 10 CE -> 9 MISO -> 12 MOSI -> 11 SCK -> 13 VCC -> Separate 3.3 source, not the arduino GND -> GND

My guess is this is because both are using SPI.

Tried the softspi method http://pastebin.com/4mv612B7 .

Same thing. I can post GET to it, parse out variables but nothing on the radio side. And I still get no output from radio.printDetails() so it just must not be starting. Commence hair pulling..

EDIT: Bloody hell, printDetails() relies on printf...... that would have been handy to figure out an hour or two ago. I can get details now. still having communication issues. Will post more debugging information in a bit.

2 Answers 2


The issue here is that the Ethernet chip locks the SPI bus thus making it impossible for NRF24L01+ to communicate with the arduino properly. Please use softSPI to fix this.


Issue one: .printDetails(); uses printh. If you don't have that included you won't get the information.

Issue two: The ide gets confused when you have two libraries with the same file. I compiled my receiver with the softspi file. Once I put the right library in it works.

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