I just recently made some changes to my 1.4 firmware to support
Man-in-the-Middle modification of ATR because some device apparently
changes the Vcc to 1.8v after reading the ATR that indicates the card
supports Class C. I don't have access to the device that exhibit
this behavior so I was using a USB Smartcard reader to test it, and my
Oscilloscope capture shows that the PC was using 5v vddio mode. The
SIMtrace 1 are 5v tolerant, and the last time I looked at Cstartup.asm
I believe we set the internal pull-ups to disabled, which is "safe"
according to the Atmel part documentation. So long as 5v IO levels
are not "on"/"fed" into the PIO lines while the device is in reset,
this is probably not an issue for SIMtrace 1 boards.
> From: Mychaela Falconia <mychaela.falconia(a)gmail.com>
> To: simtrace(a)lists.osmocom.org
> Cc:
> Bcc:
> Date: Tue, 25 Oct 2022 20:03:23 -0800
> Subject: My progress with 5V SIM investigation
> Hello SIMtrace community,
>
> I mentioned earlier on this list, and also in last week's OsmoDevCall,
> that I play with some old phones that *may* be putting out 5V toward
> the SIM, which SIMtrace2 hw does not tolerate - 5V exceeds the absolute
> maximum rating spec of SAM3S chip.
>
> As the first step in the investigation, I cobbled together a simple
> PCB design for a purely passive adapter that connects a SIM socket to
> FPC cables from current Sysmocom SIMtrace kits, plus 2.54 mm headers
> on both sides of the SIM socket providing convenient probing access to
> all signals. This trivial design can be found in my fc-small-hw Hg
> repository:
>
> https://www.freecalypso.org/hg/fc-small-hw/
>
> Look in the sim-fpc-pasv directory inside the Hg repo. I haven't sent
> this little PCB out to fab yet, but I plan on doing so when my budget
> allows it, hopefully no later than a week from now. When I get this
> adapter board fabbed and assembled, I will test it with my current
> collection of old phones (Ericsson I888, Nokia 5190 and 6190) and see
> if any of these phones put out 5V toward the SIM.
>
> Nokia 5190 and 6190 are powered by 3-cell NiMH batteries, but they
> still might put out 5V toward the SIM if they include a charge pump or
> some other boost converter. At least in TI chipset history, prior to
> our well-known Calypso+Iota chipset, their previous ABB chip Nausica
> (used in the legendary TSM30, apparently) could put out either 3V or
> 5V toward the SIM, selection under fw control, while powered by a
> 3-cell NiMH or 1-cell Li-ion battery, doing some kind of boost
> conversion for 5V. (I never found a datasheet for that ancient ABB,
> so I don't know the full details.) It will be interesting to know
> what Nokia 5190 and 6190 do in this regard. It will also be
> interesting to see what Ericsson I888 puts out: it is an older,
> higher-voltage beast, powered by a 4-cell NiMH battery, and if the
> designers felt like operating the SIM in "5V" or Class A mode, they
> could have used raw battery voltage without conversion, as the spec is
> 4.5 V minimum IIRC.
>
> During last week's OsmoDevCall Kevin said that he had some SIMtrace1
> boards with ARM7S, which the datasheet says is 5V-tolerant, and I
> recall him saying that he could send me one. To Kevin: I greatly
> appreciate your offer, and I may indeed take you up on it in another
> few weeks - but let me build my sim-fpc-pasv adapter first, and see
> what voltages are actually put out by phones in my collection.
>
> Now the really interesting phone would be Nokia 2190 - supposedly one
> of the very first PCS1900 band GSM phones sold in USA, from around
> 1995. That one is powered by a 5-cell NiMH battery and thus seems
> very likely to put out 5V toward the SIM, possibly always, without
> ever switching down to 3V. I don't have one to test, aside from a
> sealed box which I am reluctant to cut open (told it may be worth
> a fortune some day, the usual story), but another person on Reddit
> says that these phones are very finicky in terms of which SIMs they
> accept. I sent him a few of my FCSIM1 cards, equivalent to
> sysmoSIM-GR2, a pure GSM 11.11 SIM without any UICC at all, very
> old-fashioned, and my contact tells me that Nokia 2190 rejects these
> SIMs too! It was my desire to use SIMtrace to see what's happening
> with that finicky 2190 that prompted my investigation into 5V
> tolerance - and when I get my sim-fpc-pasv adapter built, I will get
> back in touch with my Nokia 2190 contact person from Reddit and see
> how he would like to proceed.
>
> M~
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