Guard time smart card?

Question

Electronics

Good afternoon. The question is extremely amateurish and very narrowly focused (for those who worked with smart cards). Before we start working with a smart card, we do not know anything about it and set the default frequency, etc., and everything seems to be clear, but there is one BUT: what about the time of receiving a byte? The standard states that its minimum time is 12 etu, and the maximum is 9600. The question is: is there any exact value for this parameter by default? or just from 12 to 9600? I always thought that 12 is by default, but while writing the firmware I began to doubt. In general, I will be glad to advice)

Answer 1

I didn’t communicate with smart cards ... a little about RFID ... I’ll lie about this)))
There is a problem with power supply, if the tag is far from the field or the field strength is low - there is not enough power to start (often at high frequencies). Therefore, the limit of 9600 is most likely protection against low power, at a lower voltage it will not start at all. He simply does not have enough energy to complete the transfer, he slowly accumulates a charge to throw out the data. Under ideal power conditions, it already rests on its own response and transmission speed.
There is another side - what was written to the Smart card: Maybe the microprocessor performs complex calculations before transmitting something to the output. The more difficult the longer.