Contactless bank cards

Cybergibbons cybergibbons at
Thu Nov 18 10:09:07 GMT 2010

On 18 November 2010 08:18, Roland Perry <lists at> wrote:
> In article <AANLkTinN1_26-O+ATrbwoKkS1jfZbfAqockcD8gGoAWX at>,
> Cybergibbons <cybergibbons at> writes
>> If you use USB, the latency and unpredictability causes issues with
>> some card readers - this doesn't work to relay to TFL readers for
>> example. However, you can use any microprocessor to perform the relay
> I don't really understand what you mean by "any microprocessor"

Sorry - I meant you can use any simple microprocessor such as an AVR
or MSP430 to perform the communication between the two PN53x.

>> to avoid this, and use an RF link instead of wires.
> An RF link with more bandwidth than USB, presumably? Or is it just "less
> latency per packet"?

It's a question of latency - by the time the data leaves the reader,
goes through some kind of USB interface, back to the PC, through an
application on the PC, back down to another USB interface and into the
emulator, the latency is high and unpredictable.

Using something far more simple and ditching USB keeps the latency low
and predictable.


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