Sparkfun nRF2401A issues with hardware

Projects Networking, Protocols, and Devices
1

I had recently purchased the nRF2401A module (SparkFun Transceiver Breakout - nRF2401A (Chip Antenna) - WRL-00152 - SparkFun Electronics)

I am having a bit of difficulty getting the modules to work. Let me begin with where I am up to now:

referencing the Arduino site: Arduino Playground - Nrf2401

I have properly installed the c++ / header files (in a properly named folder) in the library folder of the Arduino IDE. Everything compiles and uploads fine.

I then placed a 1.5? resistor from the Arduino 3.3 v to the vcc of the modules (since the sparkfun info page recommends 3v).

I have read in numerous other locations such as http://www.instructables.com/id/Arduino-Fart-O-Meter/step4/Transceiver-nRF2401A/ (if only these people used their power for good), and http://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo (this is a slightly different module), that these transceivers may require higher current for power, and their I/O pins should not take the full 5v that Arduino is supplying (as I have been doing). I'd assume I would need to purchase the logic level converter from sparkfun.

I am a unsure on all these fronts, so I wanted to confirm if these two issues are the reason, or if i am overseeing something completely. Thanks for your time.

2

To answer your questions:

The nRF24l01 has a maximum operating voltage of 3.6v so it is fine to connect it directly to the 3.3v rail of the arduino. You do not need the resistor. However, the arduino 3.3v rail is not well regulated so it is important to connect a capacitor directly across the 3.3v connectors on the module. I use 1uF others use 100uF .. both work fine.

The nRF24l01 is tolerant to 5v on its i/o pins so connecting direct the the arduino is fine.

You have not said which arduino you are using. Be aware that the connections for the mega are different from the others.

Have a look for the rf24 library. There is a lot of information around and there are good examples that are easy to follow.

3

Hey crofter,

after discussing with a couple others, and referring to the datasheet, my assumptions are correct.

The Arduino outputs 5v I/O, when the nRF2401A can only handle max 3v...so it is incorrect to plug it directly to the Arduino I/O without some form of bidirectional filter to drop down the voltage.

scroll down to page 4: https://www.sparkfun.com/datasheets/IC/nRF2401A.pdf

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danieljay:
The Arduino outputs 5v I/O, when the nRF2401A can only handle max 3v...so it is incorrect to plug it directly to the Arduino I/O without some form of bidirectional filter to drop down the voltage.

I'm afraid that I missed the subtle distinction that you have bought a nRF2401a module but I am using the more common nRF24L01 modules that can accept 5.25v on their input pins. see pdf on page http://www.nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01P
As the nRF24l01 modules are now available for less than $1 delivered to the UK it will be cheaper to buy a new module than a level shifter chip.