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A 'cost-optimized' nrf24l01 design from china

A project log for rf24boot: The NRF24L01 bootloader

nrf24l01 over-the-air bootloader for different microcontrollers

NecromantNecromant 03/13/2015 at 13:0110 Comments

Just got 10 new nrf24l01 modules from china. Now accepting bets whether these will work at all.

From a quick view (according to nordic's reference schematics, p. 69) - they are missing L1, L2, C3, C4, C6, R1, R2 and one of C8 or C9.

Discussions

Grob wrote 05/14/2015 at 11:10 point

I got some of these, at $4 for 10pcs so worth grabbing a few to test. But from my testing they are not wirelessly compatible with the nRF24L01+ modules. The seller did give me some code (SDK) that looks to be the code running on the module.

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Necromant wrote 05/14/2015 at 12:23 point

Yep, they have that NO_ACK bit flipped. So the only way to use them with geniuine stuff - forget about AUTO_ACK,

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Grob wrote 05/14/2015 at 22:48 point

I disable AA and check that most of the other registers where the correct. 

Anyway here is the code I was sent by the vendor, I found the UART part interesting as if this chip had a serial port running at 115200 like the code suggests that could be useful.

http://sz.ctfs.ftn.qq.com/ftn_handler/ad2ac54fdb946bbb3ae3fef427f2fc6ea9907ee63d07ba4233dd6a5d08c8db5f77c57c65b29134f21b15c70ed939efcb1767ccba6a8da427a92d427214628dfb/?fname=%E7%92%90%E5%AF%B8%E5%A2%96%E9%90%A9%E5%AD%98%E5%BD%83NRF.rar&k=7c306237dd149a9c99...

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Necromant wrote 05/15/2015 at 09:14 point

Yeah, I've seen that. They're using an nrf24l01 connected to that STC 8051 MCU that does have an UART. 

If you want to deal with STCs - checkout stcdude at my github.

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Necromant wrote 03/13/2015 at 13:26 point

These were dirt cheap, some $8.61 for 10 of them incl. shipping ($2.25).

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Necromant wrote 03/13/2015 at 14:57 point

Looking at the reference schematics and the missing components list - the modules have one of the differential amp outputs floating, so it likely has a 30-40% decrease in TX power. Not speaking of missing decoupling, that likely makes things even worse. Add a (most likely - rip-off asic that's less sensitive than original) we have a total 'winner'.

The one on your link with smaller PCB looks like they're lacking even more components. And unlike black ones you can't just solder them in. 

What's bugging me is that mine are missing the IREF resistor, which CAN be a total problem. Will find out if it works in the evening.

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davedarko wrote 03/13/2015 at 16:37 point

Wow, you definitely know something about those modules :) 

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Necromant wrote 03/13/2015 at 18:19 point

Well, I did take the effort to visit the analog electronics guru working on the next floor for some advice, so don't consider me an RF guru - I'm not. I'll be making a detailed writeup about this crap quite soon in my blog with schematics. 

And yes, the modules kind of worked, like it did read some registers and did receive some data. But not the data I've sent to it. In fact - looks like I'm only receiving random gibberish with these modules.

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davedarko wrote 03/13/2015 at 13:21 point

So how much cheaper where they in comparison?

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