[Question] Some modules take way longer to write() about rf24 HOT 6 CLOSED

This is likely not an issue with the library, but with the modules you have. I would suggest that the retry periods aren't working as intended. I would also assume that the radios are just having trouble communicating, in case of the PA+LNA modules, you can try shielding if none is present per https://github.com/nRF24/RF24/blob/master/COMMON_ISSUES.md

What kind of modules are you using and which work, which don't?

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Transmitting data (via electromagnetic radiation through the air) is not solely reliant on the hardware and software. There are ambient variables that we often have no control over (temperature, humidity, physical obstacles, etc). Some other factors that we can be mindful of (and attempt to compensate for) are other transmitting devices using the 2.4GHz bandwidth (WiFi & Bluetooth for example).

2.7 ms for a single 8-byte transmission seems rather long. BTW, 100 ms is the timeout that write() uses internally.

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There's a Hackaday article about identifying counterfeit nRF24L01+ chips, it might help identifying them in the future.

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What kind of modules are you using and which work, which don't?
It's always the same module, this basic one: https://de.aliexpress.com/item/1005005642753224.html
At the moment they are sending without Rx present, so I want them to not reach any destination. In this case I expect to have the timeout after 2.7us, as per retries and time defined. But one module, that previously did 2.7us now does 98000us... So probably a hardware defect?

2.7 ms for a single 8-byte transmission seems rather long. BTW, 100 ms is the timeout that write() uses internally.
Yeah, its not transmitting, just reaching the limit of retries, as I dont have a Rx present. But good to know the 100ms is the internal timeout, so probably the module is defect and the code itself times out at the 100ms mark..

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I've never considered aliexpress to be a good source for these radios, rather I think of aliexpress like an amazon-clone but much much worse. The first review on that store page calls them clones. FYI, its not a good sign if there is no writing printed on the chip itself. Since the nRF24L01 chip goes for $2 or more on mouser.com when purchased in mass quantities, I think its safe to say that a $1 radio is not using an authentic nRF24L01 chip.

The 100 ms timeout used (exclusively) in RF24::write() often indicates a wiring problem. But it is not specific to wiring; it simply means the radio is not behaving as the library expects it to. Also, you can check RF24::failureDetected after calling write() because the 100 ms timeout will assert that boolean attribute.

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Yeah, its not the best source for sure. Out of 100 modules I had 5 with a defect from production, thats ok for me. None of them use a genuine IC for sure, but all work properly so far (except this one which died during operation)
So I will book this module as "death in service" and close this case.
Thanks for the hints. My hope was that I just overlooked some register which now magically changed the content, producin this behavior :D

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