alt Hacker News> "actual regulations...emissions"
yeah, and looking at their board I see they use one of "ESP32-WROOM" modules, which has the wifi & blutooth & antennae (pre-certified by Espressif for FCC, CE so itself doesn't need testing) & flash & processor (which even has its own RC oscillator), which takes care of a whole ton of difficult stuff so all the designer needs to do is plop that module down and power it up and wire some SPI/I2C peripherals which I'm guessing don't need super fast clocks or electrical constraints. Without something like those ESP32 modules, this would be much more difficult.
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Im not an expert in emissions testing but pretty sure it still needs CE certification testing. The module shouldnt cause any problems providing that the firmware for the transmitter is configured properly, and is placed sanely in the enclosure, but the entire product must still undergo the relevant testing for 2.4GHz emitters.
Just because you use a certified module doesn't give you a free pass.
The ESP32-S3-WROOM1 module is FCC certified for its own Wifi and Bluetooth emissions when used by itself.
And, well -- that's certainly good.
But the FCC rules cover more than just Wifi and BT, and the whole rest of the widget also needs to comply with them. Of particular interest is FCC Part 15 Subpart B, which covers unintentional radiators. The device would need to comply with Part 15 Subpart B even if it had nothing to do with Wifi or BT.
Putting one part that is certified for one issue into a device doesn't extend a magical blanket of compliance to everything else that the whole of the widget contains.
Does the SPI or I2C bus (or anything else) leak RF beyond allowable limits? Eh, who knows. I certainly don't know. It's easy to say words like "it should be fine," but without testing then nobody actually knows.
The CE mark, meanwhile: That mark means exactly nothing in the US, where the author is located and the devices are sold from. The United States has zero regulatory recognition of any of the processes and/or tests that CE may cover. People often confuse this issue, wherein: They don't think it be like it is, but it do.
> Without something like those ESP32 modules, this would be much more difficult.
I don't disagree. It's important for us to recognize that we stand on the shoulders of giants, but I also think it's a little silly of a critique of someone happy about it being easier than he expected. It's true that hardware would be much harder if you had to do it all yourself, but is that meaningful? The wonders if the modern supply chain is that you don't need to do it all yourself.
The pre certified module do not exempt the product from testing. It only means that you don’t have to do the conducted testing and that it’s a higher probability for passing the other tests. There are still lots of chances to fuck up and a full radiated test of the product is required.