On Tue, Jul 6, 2010 at 7:03 PM, Luisa <[email protected]> wrote: > Hi Drasko and Sebastien, > > Drasko, my fault. I meant 9600 Hz on my last email, rather than 96Khz. > > OK, I thought you sent something like 20MHz to your card :)
> And, Sebastien, that comment was unvaluable! I couldn't get to a point > where that would had shown up from trial and error. So thanks both!. > > Don't mention it :) > Well, I'm not still getting it. I'd say my card is definetely not > answering me each 372uS. Though I've got yet some tests to be done. > Will keep on trying, but the situation is being the same, whatever I > do, the card asnwers me with just the TS at a fixed speed, above the > 372uS between bits. > > Also, just to know I'm not wrong with this as well, I'm supossed to > toggle the clock line each etu, don't I? or does the card expects a > high and just next to it, a low on the clock line? I'm using the > former, though have also tried with the latter with no success. > > As noted by Drasko, ISO7816 is not I2C or SPI (data bits synchronous to a clock signal). The bus is really asynchronous, ie the clock line is really the CPU clock signal used to drive all the internal logics, and the IO signal is driven by an UART, like a PIC or a 8051, with a baud rate generator. This is why it's called asynchronous. The etu is of course related to the clock speed, for example the atr is sent at 372 clocks cycles per ETU. FYI: the latest native card I worked with had an internal oscillator, and only uses the input clock signal to detect whether someone is trying to cheat. So the IO bit rate has really nothing to do with the input clock :-) FYI2: once unpon a time, when Roland was still young, the clock line was driven by a bare quartz oscillator made from an inverter gate, and the IO line was connected to both TxD and RxD of a RS-232 port (after level conversion). If the quartz runs a 3.57 MHz, then 3570000 / 372 = 9600 bauds and you can use a basic PC UART with the proper data bits and parity. Now everything is USB, CCID, and we have SoC and microcontrollers, so we don't need these tricks anymore! But I still have such a reader on my desk when I need to be "sure" :) The behaviour of you card is extremeley clear and normal. You basically send a 9600 Hz clock. The card detects this low frequency condition just after sending TS, which is sent in hardware, but not the other bytes. This behaviour seems to show that your card is recent and have a free running clock, not dependent on the input clock frequency. You're lucky to see TS and not a mute card. So basically the card is extremely underclocked, and not overclocked as I thought. and it thinks you're trying to hack it: observing the internal states by slowing down the CPU, which is an antique attack vector detected by all modern card hardwares. Cards typically work correctly when Fclk is between 1 and 5 MHz. Out of these bounds, the security detectors are activated and the card is muted as soon as possible. In fact, I noticed the card is giving me that TS byte alone even when > I don't toggle the clock at all during the reset sequence. > > One more argument for the free running internal clock. For the record, I'm expecting data from the card after I toggle the clock > line. > > And about the hardware, is within the allowed tollerances. My guess is > that the problem is either in my firmware, or in my spanish id card > not allowing a cold reset at 5 volts (perhaps the majority of chips > have already gone down to 3.3 or so, I don't know). > > Per ISO7816-3, all cards are *required* to work at 5 volts, and some of them accepts a lower voltage. > That's all by now. I did setup a google code account, though I've only > uploaded the schematics: > > http://openscr.googlecode.com/files/breakout.pdf > Looks very good. If I were you, I would use a GPIO to detect card insertion. This event can be used to trigger card activation, reset sequence, ATR reading and optional PPS exchange. Do you plan to connect your reader to a PC via a serial port? TxD and RxD are still free on PD0 and PD1. Regards Sebastien > Regards, > > > > Regards Sebastien > On 7/5/10, Sébastien Lorquet <[email protected]> wrote: > > You're overclocking your card and the hardware overclock detector inside > the > > card stops the card. Only TS is sent because this is automatic and > hardware > > driven, but as soon as software starts, HW detectors are enabled, the > faulty > > condition is detected and the card is muted in a while(1); loop. > > > > At reset, a card MUST be clocked a 372 etu (default params) and the clock > > must be kept within limits, ie at a max of ~4 MHz > > > > Are you sure the voltages are in the mandated range? 5V +- 5%, or 10% > don't > > remember which tolerance must be met. Card also have over / under voltage > > detectors. > > > > Sebastien > > > > On Sun, Jul 4, 2010 at 11:26 PM, Drasko DRASKOVIC < > > [email protected]> wrote: > > > >> On Sun, Jul 4, 2010 at 10:48 PM, Luisa <[email protected]> wrote: > >> > Hi, > >> > > >> > Thanks for your answers. > >> > > >> > I've got a bit further with this, though not much more either. > >> > > >> > I found out the card, albeit being initalized as the iso says, and > >> > having the clock line toggling @ 96000 Hz, is answering me with a bit > >> > each +/- 20 microseconds. > >> > >> Why are you clocking your card with 96kHz ? Should not it be clocked > >> 1-5Mhz > >> ? > >> > >> What is "bit" in your case ? Is it value during one ETU, as it should > >> be, or you are looking your clock (which is wrong) ? > >> > >> Clock your card with 1Mhz, and have in mind ETU value while decoding > >> characters, because it defines your baud rate. Inital ETU for ATR will > >> be 372/1Mhz = 372uS. "Bit" is a value taken during this period. > >> Character duration will accordingly be 1(start bit) + 8 + 1(parity > >> bit) + 2(guard bits) = 12 ETUs, i.e. 12*372uS. > >> > >> BR, > >> Drasko > >> _______________________________________________ > >> Muscle mailing list > >> [email protected] > >> http://lists.drizzle.com/mailman/listinfo/muscle > >> > > > > _______________________________________________ > Muscle mailing list > [email protected] > http://lists.drizzle.com/mailman/listinfo/muscle >
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