4 years, 4 months ago.

From development to production


I intend to start developing on an u-blox iot kit (consisting of the LPC1768 MCU + u-blox cellular module). Now what, my development is ready and I want to put everything into production. A development kit is not the way to do this so i need production grade hardware. That's the point: we are IT pros so we don't have the knowledge to "convert hardware-wise" a dev kit environment into production hardware. Above that I suppose going from a dev kit environment to production hardware is a costly endeavour (certification, ...). So my question: how do others this evolution from development to production? In case of the u-blox iot dev kit are there maybe third-parties that produce an "analogous" product based on the dev kit meant for production?

Thanks. Guy

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1 Answer

4 years, 4 months ago.

If you are planning to make more than a few handfuls of your product, yes, you'll want to have the design laid out on a PCB. I do the PCBs myself, I'm a hardware pro.

You do not necessarily have to produce certificates for EMC, unless your customer demands them, or someone complains about interference from your product!

The mbed LPC1768 module have been tested in a lab (results are on the site somewhere) and it appears to conform to EN55022 (the IT equipment EMC standard). So a competently designed PCB of similar dimensions should not have too many worries.

The usual process:

1. Carefully draw a diagram of all the things connected to the uBlox module. 2. If possible, measure the power supply current, when the product is at its busiest. 3. Sketch any physical envelope limitations. 4. Send the info to some hardware designers (who can show some 32-bit controller work), get some quotes.

The code from the mbed compiler works on target LPC1768 boards, unless there are some _WFI that are only normally tripped by the mbed interface module (the old USB MSD is an example). Trying with an LCPXpresso module flushes that problem out.

The GPL-licensed project lpc21isp can flash your LPC1768 in production with ease, free for production use, of course. It uses an FTDI USB to 3.3V UART cable from Farnell. So be sure to provide a PCB connector for the 6-way SIL to suit these.

The problem is I'm an IT/software pro and not a hardware pro ;-)

posted by Guy Dillen 24 Nov 2014

Yes, it will be best to find a handy Hardware designer, preferably near enough to visit. Demo the hardware, see if you can get a quote for the PCB layout work. Should be possible to get fixed prices for a job of that kind.

posted by Rod Coleman 24 Nov 2014

Ok thanks.

I suppose it would be a "stupid" idea if just using the u-blox dev kit "AS-IS", in eg a (ruggedised) box with connectors on it to plug the used (external) sensors, in a production environment? Thanks.

posted by Guy Dillen 26 Nov 2014

I have done this with the mbed module LPC1768, in cases of very low volume production.

But in every case, the inputs, outputs and power supply need to be protected from transient voltages and ESD, and prevented from emission of EM noise - by choice of protection diodes, ferrite beads, and common-mode chokes.

In many cases, electrical isolation of IO is required, to prevent "Ground Loops".

Most industrial, vehicle etc. environments are astonishingly hazardous to little microcontroller IO!

posted by Rod Coleman 26 Nov 2014

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