IMP003 - benefits of using in new designs

I’ve read the press release, the draft spec and found Hugo discussing it with EE Times but couldn’t find much else on the IMP003 so thought I’d kick off a discussion.

I plan to integrate a solder down IMP into one of my designs but now the IMP003 is out I’m keen to know more about it before settling on IMP002 or 003. I’ve identified some benefits of the IMP003 over the previous IMPs as follows:

  • smaller
  • ability to add more memory
  • M4 Cortex processor (I imagine the API would need to be updated to take advantage of additional M4 functionality)
  • higher operating temp
  • processor can operate with Wi-Fi turned off, allowing lower current draw (I assume)

Some downsides I noticed are:

  • reduced sensitivity (10dB less typical sensitivity, not sure why as I imagine all IMPs would use the same radio?)
  • no recommended PCB layout available
  • no reference designs available
  • no breakout board available

I’ve a few burning questions:
1/ What will the IMP003 cost and is it likely they will be more cost effective to use in new designs as opposed to an IMP002?
2/ The spec shows external SPI flash memory - is this required for the IMP003 to operate?
3/ The ability to turn off the radio will enable the IMP003 to draw less current while continuing to operate as usually both the processor and radio are powered on and will consume at least 5mA in power save mode. What is the current draw when the radio is turned off?
4/ The IMP003 is obviously smaller than previous IMPs but are there any other reasons one would be better off using the 003 in a new design rather than the 002?
5/ Are circuit board recommended layout designs, reference designs and breakout boards on their way?
6/ Any guesses on what the other “platform” mentioned in the EE Time article is??? :slight_smile:

I realise it’s only early days for the IMP003 but: gimme, gimme, gimme! :slight_smile:



not an expert here but… having a look at the documents;

I didn’t see anything different in the specifications for low power WiFi modes. the imp002 and imp003 show a power-save mode with typical 5mA consumption. Maybe I did not read the documents closely enough. I think both modules have sleep mode with 6uA consumption.

The imp003 has a footprint that would seem to require more than a 2-layer board. The imp003 requires one to design and make their own antenna.

on this page


it is stated

"in most cases you don't need to use a "user" SPI bus to attach extra storage to the imp003"

I would suppose that if your design is size-critical this new one is the only module for you but you need to be prepared for some extra work.

I am going to stick with imp002 and also keep an eye out for the new network technology.

There is a reference design for the imp003, (Amy) and as stated, it does require you to design and cert your own antenna, and there are a number of support components.

G’day @mjkuwp94 and @MakeDeck, thanks for responding.

Correct, the spec only states 3 modes: normal with Wi-Fi, normal with Wi-Fi in power save mode and sleep with Wi-Fi off; 80mA, 5mA and 6uA respectively. If these are the only modes available, what benefit is the “low power” configuration on page 16 of the spec? I assumed this configuration enabled the processor to operate with the Wi-Fi turned off which would effectively be a fourth power state. But you know what they say about assume.

Yeah, I was thinking 2 maybe three layer board. One could potentially get away with a one or two layer board if the non-GND centre pins weren’t used.

The SPI bus statement on the pin mux page is a little vague - I take this paragraph to mean one doesn’t have to use other SPI buses for extra storage as the IMP003 provides a dedicated SPI bus for this purpose. Then again the Amy reference design states “and required SPI flash”. So I guess external storage is required. Either way the spec is a bit vague for my liking on this front.

I missed the Amy breakout board, thanks @MakeDeck. If most of those components are required to make the IMP003 work, it doesn’t look like an IMP003 design will be much smaller than an IMP002 design.

The essential point here is MakeDeck’s, that imp003 requires designing and certifying your own antenna. This is a lengthy and costly process (for regulatory reasons that we can do nothing about), and imp003 is aimed squarely at those manufacturers whose expected volumes are so enormous that they can amortise that substantial cost. Unlike imp001 and imp002, it’s not also intended for the maker or low-volume community (though I guess that’s also what we said about imp002 at first).

So imp003 may not be the droid you’re looking for. But for reference: 80mA, 5mA and 6uA are with the “low-power” configuration. In the alternative “low-cost” configuration, you don’t get the 6uA mode.

On the SPI flash thing: imp001 and imp002 both have internal SPI flashes which we use for our own data. But a fair number of customers end up adding a second SPI flash, externally, to store their own data. So for imp003, we mopped those two parts up into one: fitting an external SPI flash is required, a 4Mbit (not 2Mbit; the datasheet is not merely vague but wrong on this) one if you don’t need any yourself, a larger-than-4Mbit one if you want some for your own data. One 8Mbit chip is cheaper than two 4Mbit ones would be, as well as needing less board space and fewer of the imp’s valuable pins.


@peter I have a breakout board nearly completed just in case the imp003 does become available (at low volume) and you are able to cert an antenna. :slight_smile:

Sparkfun has a good tutorial on FCC certification.

If you can re-use components that have been certified by another entity the costs are fairly inexpensive. Certifying your own intentional radiator will run you around $12k. The FCC has a number of labs to help then verify new licenses, but the process still takes quite some time. Some of the WiMax/LTE transmitters I support are typically taking 4-6 months.

If someone went through FCC intentional transmitter certification with IMP003, I suggest to publish it on the Electric Imp website. The whole community is interested in that, including Electric Imp self.

We’re likely to get FCC modular approval for IMP003 when paired with a specific chip antenna. Stay tuned.

Yay! Is it expected in a few months?

Likely, yes, but they’re unlikely to be available in small quantity for retail purchase.

For FCC modular approval, why didn’t you choose PCB antenna like Amy? A chip antenna has reduced efficiency/range.

Mainly, because a chip antenna is slightly harder to get wrong, and it’s very small - due to imp003’s size, some customers are building it into very small devices.

Some chip antennas have fairly decent performance (like the one we’re doing approvals with) but you’ll be glad to know we will be providing a PCB antenna design - with FCC modular approvals and 3D performance plots - for people to use in their designs.

You say “FCC modular approval” will it look like a solder down module like IMP002? Or is it a reference design?

It’s a solder down module, but to use the modular approval you’d need to copy our antenna trace layout etc. So, part module part reference design.

How is the progress on FCC modular approval for chip antenna and PIFA? What can I expect?

The antenna testing has gone well (we did 3D scans to verify these on both 1.0 and 1.6mm boards) so approvals are next. Likely will be done by december.

imp003 samples should be available on digikey in a week or so.

Is it correct that for IMP003+PIFA I need to copy the antenna trace layout exactly and not need FCC certification?

Is it correct that for IMP003+chip antenna I can change the trace to the chip antenna and not need FCC certification?

Can I also place a U.FL connector and not need FCC certification?

FCC cert is not complete yet on IMP003, but yes, that’s the idea. You’d have to use a chip antenna of the same or worse performance.

If you place u.FL you will need to do cert with whatever antenna you pick.

Which chip antenna is used for the Imp003 approvals ?