Hello
i trying to design a smart card interface using an 8051 UART,
a pierce oscillator circuit.
the design seams to be working, as i'm getting response
from the smart card, however, i've having difficulty
controlling the clock.
the sequence after card insertion is
1. power the card. i use an p3.3 for this
2. take reset pin high. use p3.6
3. start the clock
i use a NOT gate to power the oscillator circuit. pin3.7 is connected to the input of the gate,
and the output is connected to the VCC of the pierce circuit (which ialso consists of a not gate
which drives the output high.
i also tried a ULN2003, with a pull-up at the output.
4. monitor RI bit and capture any UART data.
HOwever, this sequence doesn't seam to work find
But if i disconnect the VCC of the oscillator while the code is waiting for response,
and the connect it back, i get the full response, which is consistent over many tries,
and valid according to 7816 protocol.
That made me believe that the circuit turning the clock on and off doesn't work find. like i stated i tried various approaches to trigger the clock, but it doesn't seam to work efficiently
I have attached the two circuits here, though they are very basic. i want to know if there is a better way, or
maybe i'm doing something wrong.
i also want to mention that i have access to limited resources, such as a dedicated smartcard reader chip, and as well as a wide of components.
i trying to design a smart card interface using an 8051 UART,
a pierce oscillator circuit.
the design seams to be working, as i'm getting response
from the smart card, however, i've having difficulty
controlling the clock.
the sequence after card insertion is
1. power the card. i use an p3.3 for this
2. take reset pin high. use p3.6
3. start the clock
i use a NOT gate to power the oscillator circuit. pin3.7 is connected to the input of the gate,
and the output is connected to the VCC of the pierce circuit (which ialso consists of a not gate
which drives the output high.
i also tried a ULN2003, with a pull-up at the output.
4. monitor RI bit and capture any UART data.
HOwever, this sequence doesn't seam to work find
But if i disconnect the VCC of the oscillator while the code is waiting for response,
and the connect it back, i get the full response, which is consistent over many tries,
and valid according to 7816 protocol.
That made me believe that the circuit turning the clock on and off doesn't work find. like i stated i tried various approaches to trigger the clock, but it doesn't seam to work efficiently
I have attached the two circuits here, though they are very basic. i want to know if there is a better way, or
maybe i'm doing something wrong.
i also want to mention that i have access to limited resources, such as a dedicated smartcard reader chip, and as well as a wide of components.
