SD card + nRF24L01 SPI conflict

Projects Networking, Protocols, and Devices
1

Hi,

I am trying to connect two devices into SPI but I have had conflict problems! Does anyone have done it?
I used RF24 library and SD library into the same sketch and it doesnt comunicate correctly.

Thank you!

2

Hi,
I'm in the same condition. I tried to change the used pin and the library, but seems that sd card and NRF24L01, on the same SPI, doesn't work properly.
I also know that there are software problems with Arduino DUE (it doesn't compile the sketch).
Waiting for a solution I connected two atmega328, the first receive/send from NRF24L01 and the second write/read from the SDcard. The two Atmega328 comunicate with a I2C protocol (two simple wire between processors).

My configuration was: Arduino UNO, microsd card and NRF24L01+

Regards,
Tredipunta.

3

I don't know about the Due. Post the code you are trying. Maybe I can help.

If you post the Due code, please include the compiler fail messages.

edit: Also post a link to both the nRF24L01and the SD card hardware.
I prefer the Uno code posted here. If you plan on posting the Due code, there is a section specifically for the Due. You should post it there.

4

any resolution on this ? i just came up against it (mega + sdcard + rf24)

5

Probably not. The only thing useful in this thread is the title and you are better off restating your particular problem, along with your code.

Your problem is very likely to be pin clash ( as was the other stuff)

I have never used my NRF24s but I noticed that the programme called pin 53. This is the standard pin that must be held as output for the SD Card, indeed a Mega shield I have calls this for SD card select - no choice. It doesn't sound like a good idea to use it for the NRF, and you might check on that to start with.

6

im working it out, theres an option for spi speed in sdfatlib library, choose it to div 4 which is same as rf24 lib, and use seperate cs pins,

funny thing is it works on my breadboard model, but not on my production one,

problem is when i transmit it stops the rf working from then on...

sd.begin(chipSelect, SPI_HALF_SPEED)

7

wow, what it was, was something power related. as i had the sd card running on 3v3 straight from the rf24 3v3 pin next to it

if the sd was initialised, once i transmitted on with the rf24 my rf24 just stopped working after that, but if i didnt initialise the sd it was fine.

so i hooked the sd up to 5v line instead and now it works fine (sd has inputs to run of either)

ps tried a decoupling 0.1uf cap accross the rf24 v+ & gnd and it didnt help but it must be something ripple/surge/interference related

8

Try 47 - 100 uF. The 3.3 V regulator on most Arduino devices is only good for more than 50 mA.
The larger filter cap helps to smooth the power to the radio and is the most common failing of the Uno or Mega boards 3.3 v power supply.

Doc

9

thats sounds right. i have the mega. and i did think of trying a larger cap and watching the line with a scope, but seems it works fine off 5v i think ill stick with that unless i run into more troubles (less work)

thanks for your suggestion