NRF24L01 / RF24 - Couldn't Find a Digit in Preamble

I'm trying to communicate between two Arduinos with a different kind of setup that I've described below. When I send a message, I receive only the first two characters of the message and I get an error that says, "Coudn't finD a digit in preamble!" I'm hoping that someone can help me track down the problem.

Here's my setup:

I have a Mega that's using an RFID reader and an SD card reader, both of which use SPI. I was able to get both of those to work together, but I couldn't get the NRF24L01 to work with the SD card. So I changed the RF24 library to use Software SPI for the radio.

On the other side, I have an Uno that doesn't have any other SPI devices, so I'm using hardware SPI.

On both radios, I've soldered a capacitor to the VCC and GND pins.

Here's what I get for the Mega:

STATUS = 0x0e RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=7 TX_FULL=0
RX_ADDR_P0-1 = 0xf0f0f0f0e1 0xf0f0f0f0d2
RX_ADDR_P2-5 = 0xc3 0xc4 0xc5 0xc6
TX_ADDR = 0xf0f0f0f0e1
RX_PW_P0-6 = 0x08 0x08 0x00 0x00 0x00 0x00
EN_AA = 0x00
EN_RXADDR = 0x02
RF_CH = 0x4c
RF_SETUP = 0x05
CONFIG = 0x0f
DYNPD/FEATURE = 0x00 0x00
Data Rate = 1MBPS
Model = nRF24L01+
CRC Length = 16 bits
PA Power = PA_HIGH

and here's what I get for the Uno:

STATUS = 0x0e RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=7 TX_FULL=0
RX_ADDR_P0-1 = 0xf0f0f0f0d2 0xf0f0f0f0e1
RX_ADDR_P2-5 = 0xc3 0xc4 0xc5 0xc6
TX_ADDR = 0xf0f0f0f0d2
RX_PW_P0-6 = 0x08 0x08 0x00 0x00 0x00 0x00
EN_AA = 0x00
EN_RXADDR = 0x03
RF_CH = 0x4c
RF_SETUP = 0x07
CONFIG = 0x0f
DYNPD/FEATURE = 0x00 0x00
Data Rate = 1MBPS
Model = nRF24L01+
CRC Length = 16 bits
PA Power = PA_HIGH

No matter what I send, I receive only two characters, and then the message:
"Couldn't find a digit in preamble!"

Any ideas?

I'd recommend using the basic examples first for the nRF and the library you are using to drive it. Make sure those basic examples work. If they don't, then you have a more fundamental problem. Once you verify the basic examples work, then try it with your system. If that doesn't work, but basic examples work, then the problem is likely with your nRF config.

swmcdonnell:
INo matter what I send, I receive only two characters, and then the message:
"Couldn't find a digit in preamble!"

Any ideas?

As you have not posted your program code I have none.

Have a look at this Simple nRF24L01+ Tutorial.

Wireless problems can be very difficult to debug so get the wireless part working on its own before you start adding any other features.

The examples are as simple as I could make them and they have worked for other Forum members. If you get stuck it will be easier to help with code that I am familiar with. Start by getting the first example to work

...R

freaklabs:
Hi. Has there been any progress on this issue?

What progress did you have in mind?

Have you studied the link in Reply #2

Or are you just using this to increase your Post count?

...R