Author Topic: Designing a better RFM69 radio module  (Read 10224 times)

perky

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Re: Designing a better RFM69 radio module
« Reply #30 on: June 10, 2016, 11:21:55 PM »
I've got one for ya, Felix.  How about you find a way to unequivocally encode whether the radio is HW or W!!!!   No more "I didn't know that I was supposed to uncomment that line..."

Tom
PS: I know this isn't an RF feature but it sure beats trying to get people to RTFM!

You bet.
Tom, I am sure you see this as often as I do and it's one of the most annoying things, both to the user and to us trying to help. Should have been a feature of the RFM module. I am thinking a new RFM module could sacrifice one of the less significant DIO pins (if the NC is used for something more important) to mark the difference between a W and HW. Boy would that solve a lot of issues.
In all honesty the RTFM in this case is really in the top 10-15 lines of settings and headers of any sketch, and it's commented with a !
How that is so hard eludes me. Anyway this is definitely on the must-do list of this module, whenever and if it will ever happen.
You could the spare IO pin for this. If you had a RFM69CW only variant you could force this to be the opposite normal state that it would be for a dual version (i.e. one that uses the same IO pin to force the mux to RFIO), just a pull-up or pull-down/GND would do it given that you won't have the RF switch.
Mark.

joelucid

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Re: Designing a better RFM69 radio module
« Reply #31 on: September 23, 2016, 03:41:18 AM »
I recently reviewed the FCC certification process a bit and found this: http://www.emcfastpass.com/rf-modules/

Turns out you can use a pre-approved module and then save big on the device certification.

So that could be another differentiator for a custom module: FCC module pre-certification. BTW, how do others approach this? Perky, you sound like your building commercial products at times. Do you certify each product separately or do you use the module certification path?

Joe

perky

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Re: Designing a better RFM69 radio module
« Reply #32 on: September 23, 2016, 05:44:42 AM »
Module certification simply gives you a warm feeling that the final product will pass, but it all depends on the final system. Self certification is possible as long as you can prove due diligence in court, and choosing a certified module (which BTW will have been tested in a typical representative setup) goes some way towards it. Unfortunately you can't just slap in a certified module into a product and guarantee compliance.
Mark.

joelucid

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Re: Designing a better RFM69 radio module
« Reply #33 on: September 23, 2016, 05:51:04 AM »
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Module certification simply gives you a warm feeling that the final product will pass, but it all depends on the final system.

I think it goes beyond in the US (see https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=50&tn=916170):

Quote
A modular grant for a device eliminates the need for a host product to obtain its own separate certification for the specific transmitter component; however, a host product is still required to comply with all other applicable equipment authorizations for other FCC regulations, requirements and equipment functions not associated with the transmitter module portion.

Once you have the module certified you don't need to do RF certification of the end product.

Joe

perky

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Re: Designing a better RFM69 radio module
« Reply #34 on: September 23, 2016, 06:18:07 AM »
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Once you have the module certified you don't need to do RF certification of the end product.

You have to be careful with terminology here. Technically you will need to state that your product meets the relevant specifications, this is a form of self certification. So what this is really saying is that if you have chosen a pre-certified module, *and* you have been diligent in your layout, antenna choice and careful about all the other circuitry, then you could get away with self certifying and a court would see that as enough due diligence. But the onus is on you to ensure the final product complies, and if it doesn't and it hasn't been formally tested you will need to show you have done everything 'reasonable' to ensure it does.
Mark.

joelucid

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Re: Designing a better RFM69 radio module
« Reply #35 on: September 23, 2016, 07:27:11 AM »
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Technically you will need to state that your product meets the relevant specifications, this is a form of self certification.

Ok, just read a little deeper and indeed I've been inaccurate. For ISM devices you need a declaration of conformance (DoC) instead of certification.  A DoC can only be provided by an FCC accredited lab which will do the required RF testing. The FCC is not involved as you say although the lab has to provide the test results at request of the FCC.

It does seem that if you use a pre-certified a module you don't need the declaration of conformance as intentional radiator. So practically speaking using such a module still would greatly reduce conformance costs.

Joe

perky

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Re: Designing a better RFM69 radio module
« Reply #36 on: September 23, 2016, 09:48:43 AM »
In Europe we have to affix a CE mark. You can self-certify, but you have to provide a CE 'technical file' with everything you have done to ensure conformance so you can prove in court if necessary you've been diligent. I don't believe there is a specific mandatory requirement to have it formally tested using Directive 1999/5/EC (R&TTE), but it's very risky IMO not to at least do some testing:
http://www.nwemc.com/reference/white-papers/us-and-eu-emc-compliance-of-wireless-devices
Mark.

joelucid

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Re: Designing a better RFM69 radio module
« Reply #37 on: September 23, 2016, 10:14:40 AM »
Quote
In Europe we have to affix a CE mark. You can self-certify, but you have to provide a CE 'technical file' with everything you have done to ensure conformance so you can prove in court if necessary you've been diligent.

Right. I was aware that it's different in Europe. And of course it's always possible that the overall device design causes directional radiation so it definitely seems appropriate to measure the whole product prior to shipping in Europe - even if the module is pre-certified.

raggedyanne

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Re: Designing a better RFM69 radio module
« Reply #38 on: September 24, 2016, 02:37:57 AM »
I looked at a RFM69HW with SX1231H yesterday from Semtech , If the device is $3 wholesale from the manufacturer , could you design/build cheaper or equal that is ETSI/FCC compliant ?

Edit:
That price is restricted to employees  :'(
The chip is $1 & not for export unless from a registered reseller  >:(
« Last Edit: September 25, 2016, 06:40:35 PM by Felix »