Does custom firmware invalidate FCC modular approval?

[ecorm]

When using a third party pre-approved module, does using my own custom firmware invalidate the modular approval status of the module?

More specifically I would like to use a certain pre-approved nRF52805 module, but it comes preloaded with BLE firmware and an AT command interface that allows it to be customized somewhat.

I don't want to pay the exorbitant Bluetooth Qualification fees that bars entry to small start-ups and open-source projects. The device I'm developing is a wireless remote control that can only be paired with another device I'm also developing. So I would prefer to install firmware that uses the Gazell protocol stack instead, which I understand to be royalty-free. Ideally, I would like the module to also run my custom remote control firmware instead of having a separate host MCU.

So, does the modular approval status get invalidated if:

1. I install custom application firmware that runs on top of the Gazell protocol stack?

2. I install the Gazell protocol stack and minimal firmware that allows the module to communicate with a host MCU running the custom application?

[Susheel Nuguru]

More specifically I would like to use a certain pre-approved nRF52805 module, but it comes preloaded with BLE firmware and an AT command interface that allows it to be customized somewhat.

The certificationm most likely will not become invalid but you might need to do some other minor certification for your application. Buying a certified module should not restrict you from flashing your own firmware on the module,  but it also depends on what kind of extra certification the module makers are providing and you need to call the module maker to be sure about which your concerns. We cannot answer this for the module makers. 

[ecorm]

Thank you for the prompt response.

Susheel Nuguru said:

but it also depends on what kind of extra certification the module makers are providing

Could you elaborate what you mean by "extra certification"? I don't understand how a module can be "extra" certified. The way I understand it, it's either certified, or it's not.

Susheel Nuguru said:

you need to call the module maker to be sure about which your concerns

The only response I got from one of the module makers is "you can use a different protocol stack without violating FCC certifications." While that's good to know, the extreme brevity of the response is not entirely convincing.

Another module maker would not even give me the time of day unless I provided them with production forecasts and estimates. While it does have potential for commercialization in a niche market, this is currently a side project for me.

I'll try contacting a test house to see if they can help shed some light on my question.

[Susheel Nuguru]

ecorm,

What we certify is the hardware itself and the use of the RADIO by our protocol stack. Any application accessing the RADIO features though our qualified protocol only though the certified module hardware SHOULD not need any other certifications on your end but you need to pay some declaration fee (for example if you use BLE and advertise it as BLE product)

Yes, it is best to reach out to a local test house to shed more light very specific to your application.

[ecorm]

Susheel Nuguru said:

Any application accessing the RADIO features though our qualified protocol only though the certified module hardware

Is Gazell a "qualified protocol" that's been certified?

Susheel Nuguru said:

but you need to pay some declaration fee (for example if you use BLE and advertise it as BLE product)

The Bluetooth Qualification fee ($10,350 starting in 2024), which effectively blocks hobbyists from commercializing their ideas at a small scale, is the whole reason why I want to use the Gazell protocol instead. My application does not require interoperability with devices from other manufacturers.

You'd think that module makers would capitalize on the idea of providing a module that uses a cost-free protocol stack, and have their products certified with Gazell-based firmware.

[ecorm]

I have just stumbled upon this App Note from Wurth Elektronik that explains things better than anything I have found so far:

ANR031 - Certification of custom modules

https://www.we-online.com/components/media/o705723v410%20ANR031_CertificationCustomModule.pdf

As a bonus, they have nRF-based modules which use a proprietary protocol. I'll check them out to confirm they are royalty-free and appropriate for my application. Note: I am not affiliated with Wurth Elektronik in any way, and I'm not even an existing customer.