UART0 receive problem

[Prasad.Nagapati]

Hi All,

I need a help, basically I want to tap the I/O  line between a smart
card and smart card reader.

For this I am using JNUT board 1.3H, where I want to connect the UART0
Rx line to the above mentioned I/O line.

What is the extra circuitry I need to Tap this I/O line.

Is it sufficient to connect the I/O line from smart card via a pull up
resistor to the Rx pin of UART0? Or there is a level shifter is
required?

Smart card also works in the +5V,

Please help me I am confused in this.

Regards
Prasad



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[Ethernut]

Prasad.Nagapati@... wrote:

> I need a help, basically I want to tap the I/O  line between a smart
> card and smart card reader.
>
> For this I am using JNUT board 1.3H, where I want to connect the UART0
> Rx line to the above mentioned I/O line.
>
> What is the extra circuitry I need to Tap this I/O line.
>
> Is it sufficient to connect the I/O line from smart card via a pull up
> resistor to the Rx pin of UART0? Or there is a level shifter is
> required?
>
> Smart card also works in the +5V,

If the smart card interface is 5V then you simply connect expansion port
pin 39. And, of course, GND (pins 5, 6, 7 or 8).

First problem:
You need to remove R18, otherwise the RX output of IC6 will work against
your smart card and one of them will become damaged sooner or later.
This is an intentionally larger SMD resistor, so it shouldn't be too
difficult to remove it.

Second problem:
Needless to say that, after removing R18, your receiver at the DB-9 is gone.

Third problem:
When programming the board, you need to remove the new connection at pin
39. Otherwise programming will fail.

To avoid all these problems, why not use UART1 and connect the smart
card to expansion port pin 57?

Here's the expansion port layout
http://www.ethernut.de/en/hardware/enut1/ports.html
(Do not mount R33! This is for UART1 routed to the DB-9 only.)

For the software use

NutRegisterDevice(&DEV_UART1, 0, 0);
fp = fopen(DEV_UART1_NAME, "r+");
fread(fp,....);

The big advantage is, that you don't need to modify the hardware and
UART0 at the DB-9 connector is still available.

Harald

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[Prasad.Nagapati]

Thank You Harald,

As you said I will use the UART1 only, sorry to say this I don't know
why I have forgotten there is a second UART in the board :-(

Will try with this and check.

Regards
Prasad

-----Original Message-----
From: en-nut-discussion-bounces@...
[mailto:en-nut-discussion-bounces@...] On Behalf Of Harald Kipp
Sent: Wednesday, June 10, 2009 11:02 PM
To: Ethernut User Chat (English)
Subject: Re: [En-Nut-Discussion] UART0 receive problem

Prasad.Nagapati@... wrote:

> I need a help, basically I want to tap the I/O  line between a smart
> card and smart card reader.
>
> For this I am using JNUT board 1.3H, where I want to connect the UART0

> Rx line to the above mentioned I/O line.
>
> What is the extra circuitry I need to Tap this I/O line.
>
> Is it sufficient to connect the I/O line from smart card via a pull up

> resistor to the Rx pin of UART0? Or there is a level shifter is
> required?
>
> Smart card also works in the +5V,

If the smart card interface is 5V then you simply connect expansion port
pin 39. And, of course, GND (pins 5, 6, 7 or 8).

First problem:
You need to remove R18, otherwise the RX output of IC6 will work against
your smart card and one of them will become damaged sooner or later.
This is an intentionally larger SMD resistor, so it shouldn't be too
difficult to remove it.

Second problem:
Needless to say that, after removing R18, your receiver at the DB-9 is
gone.

Third problem:
When programming the board, you need to remove the new connection at pin
39. Otherwise programming will fail.

To avoid all these problems, why not use UART1 and connect the smart
card to expansion port pin 57?

Here's the expansion port layout
http://www.ethernut.de/en/hardware/enut1/ports.html
(Do not mount R33! This is for UART1 routed to the DB-9 only.)

For the software use

NutRegisterDevice(&DEV_UART1, 0, 0);
fp = fopen(DEV_UART1_NAME, "r+");
fread(fp,....);

The big advantage is, that you don't need to modify the hardware and
UART0 at the DB-9 connector is still available.

Harald

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[Prasad.Nagapati]

 
Hi Harald,

As you mentioned I am using UART1 now, and connected it to directly the
smart card I/O line which operates at +5V.
Smart card settings are 9600, 8 data bit, Even parity, 1 stop bit. Even
I configured the same in my code also.

But I am getting random data, what could be the reason, do I need an
inverter before connecting to the Rx of UART1?

Please help me regarding this. Sample code below

/*
 * Sniffer code sample.
 */
int main(void)
{
    int got;
    int i;
    u_long baud = 9600;
        unsigned char parity = 2; // even parity
        unsigned char stopBit = 1; // 1 stop bit
    FILE *uart;
        FILE *uart1;
    TCPSOCKET *sock;
    u_char mac[6] = { 0x00, 0x06, 0x98, 0x00, 0x00, 0x55 };

    /* UART0*/
        NutRegisterDevice(&DEV_UART, 0, 0);
    uart = fopen(DEV_UART_NAME, "r+");

    _ioctl(_fileno(uart), UART_SETSPEED, &baud);
        _ioctl(_fileno(uart), UART_SETPARITY , &parity);
        _ioctl(_fileno(uart), UART_SETSTOPBITS, &stopBit);

        /*UART1 */

        NutRegisterDevice(&DEV_UART1, 0, 0);
        uart1 = fopen(DEV_UART1_NAME, "r+");
    _ioctl(_fileno(uart1), UART_SETSPEED, &baud);
        _ioctl(_fileno(uart1), UART_SETPARITY , &parity);
        _ioctl(_fileno(uart1), UART_SETSTOPBITS, &stopBit);

        /* ETHERNUT */
        NutRegisterDevice(&DEV_ETHER, 0x8300, 5);
    NutNetLoadConfig(DEV_ETHER_NAME);
    memcpy(confnet.cdn_mac, mac, 6);
    NutNetSaveConfig();

    /*
     * Setup the ethernet device. Try DHCP first. If this is
     * the first time boot with empty EEPROM and no DHCP server
     * was found, use hardcoded values.
     */
    if (NutDhcpIfConfig("eth0", 0, 60000))
        {
        if (NutDhcpIfConfig("eth0", mac, 60000))
                {
            u_long ip_addr = inet_addr("192.168.192.100");
            u_long ip_mask = inet_addr("255.255.255.0");

            NutNetIfConfig("eth0", mac, ip_addr, ip_mask);
            /* If not in a local network, we must also call
               NutIpRouteAdd() to configure the routing. */
        }
    }

        fprintf(uart,"IP: %s\n", inet_ntoa(confnet.cdn_ip_addr));


    /*
     * The low level function read() will grab all available bytes
     * from the input buffer. If the buffer is empty, the call will
     * block until something is available for reading.
     */
    /*
        * Create a socket.
        */
    if ((sock = NutTcpCreateSocket()) != 0)
        {
        /*
            * Listen on port 23. If we return, we got a client.
            */
        if (NutTcpAccept(sock, 23) == 0)
                {

            /*
                * Open a stream and associate it with the socket, so
                * we can use standard I/O. Note, that socket streams
                * currently do support text mode.
                */
            if ((stream = _fdopen((int) sock, "r+b")) != 0)
                        {
                                /*
                                * Send a welcome banner.
                                */
                                fputs_P(banner_P, stream);
                                /*
                                * Flush output and read a line.
                                */
                                fflush(stream);
                                for (i = 0;; i++)
                                {
                                        int i;

                                        got = _read(_fileno(uart1),
inbuf, sizeof(inbuf));
                                       
                                        fprintf(stream,"bytes read
%d\r\n",got);
                                        for(i=0;i<got;i++)
                                        {
       
fprintf(stream,"\nrecieved char is %x",inbuf[i]);
                                        }
                                        fprintf(stream,"\r\n");
                                       
                                }
                               
                        }
                }
        }
        /*
     * Nut/OS never expects a thread to return. So we enter an
     * endless loop here.
     */
    /*
        * Close our socket.
        */
    NutTcpCloseSocket(sock);
        while(1);
}


Regards
Prasad


-----Original Message-----
From: en-nut-discussion-bounces@...
[mailto:en-nut-discussion-bounces@...] On Behalf Of Harald Kipp
Sent: Wednesday, June 10, 2009 11:02 PM
To: Ethernut User Chat (English)
Subject: Re: [En-Nut-Discussion] UART0 receive problem

Prasad.Nagapati@... wrote:

> I need a help, basically I want to tap the I/O  line between a smart
> card and smart card reader.
>
> For this I am using JNUT board 1.3H, where I want to connect the UART0

> Rx line to the above mentioned I/O line.
>
> What is the extra circuitry I need to Tap this I/O line.
>
> Is it sufficient to connect the I/O line from smart card via a pull up

> resistor to the Rx pin of UART0? Or there is a level shifter is
> required?
>
> Smart card also works in the +5V,

If the smart card interface is 5V then you simply connect expansion port
pin 39. And, of course, GND (pins 5, 6, 7 or 8).

First problem:
You need to remove R18, otherwise the RX output of IC6 will work against
your smart card and one of them will become damaged sooner or later.
This is an intentionally larger SMD resistor, so it shouldn't be too
difficult to remove it.

Second problem:
Needless to say that, after removing R18, your receiver at the DB-9 is
gone.

Third problem:
When programming the board, you need to remove the new connection at pin
39. Otherwise programming will fail.

To avoid all these problems, why not use UART1 and connect the smart
card to expansion port pin 57?

Here's the expansion port layout
http://www.ethernut.de/en/hardware/enut1/ports.html
(Do not mount R33! This is for UART1 routed to the DB-9 only.)

For the software use

NutRegisterDevice(&DEV_UART1, 0, 0);
fp = fopen(DEV_UART1_NAME, "r+");
fread(fp,....);

The big advantage is, that you don't need to modify the hardware and
UART0 at the DB-9 connector is still available.

Harald

_______________________________________________
http://lists.egnite.de/mailman/listinfo/en-nut-discussion
_______________________________________________
http://lists.egnite.de/mailman/listinfo/en-nut-discussion

[Ethernut]

Prasad.Nagapati@... wrote:

> But I am getting random data, what could be the reason, do I need an
> inverter before connecting to the Rx of UART1?

Typically not, but could be. I'm not familiar with smart cards.


> Please help me regarding this. Sample code below

IMHO, this code is too complicated for testing. I recommend to remove
everything which is not related to the smart card sniffing. Remove all
the network stuff. Simply use DEV_DEBUG with stdio to output the data.

If you still get random data with minimalist code, then most likely the
problem is not caused by a bug in your application.

Harald

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[Bernd Walter-2]

On Thu, Jun 11, 2009 at 02:12:18PM +0800, Prasad.Nagapati@... wrote:

>  
> Hi Harald,
>
> As you mentioned I am using UART1 now, and connected it to directly the
> smart card I/O line which operates at +5V.
> Smart card settings are 9600, 8 data bit, Even parity, 1 stop bit. Even
> I configured the same in my code also.
>
> But I am getting random data, what could be the reason, do I need an
> inverter before connecting to the Rx of UART1?

Random data ist usually a problem of false settings.
A scope is a good tool to find out if timing and levels are Ok.
Parity can be difficult to verify unless you send single
characters.

I never saw the requirement for an inverter.
All devices normaly agree that high level is idle.
So you should measure 5V is nothing is send.
Some devices however disable their driver in some situations to
allow multiple slaves.
Therefor it is usually a good idea to enable the pull-up on the RX line.

Normaly I programm the uart myself and don't use Ethernet code
for it, so I can comment on your code.

--
B.Walter <bernd@...> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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[Ethernut]

Prasad.Nagapati@... wrote:

> But I am getting random data, what could be the reason, do I need an
> inverter before connecting to the Rx of UART1?

Typically not, but could be. I'm not familiar with smart cards.


> Please help me regarding this. Sample code below

IMHO, this code is too complicated for testing. I recommend to remove
everything which is not related to the smart card sniffing. Remove all
the network stuff. Simply use DEV_DEBUG with stdio to output the data.

If you still get random data with minimalist code, then most likely the
problem is not caused by a bug in your application.

Harald


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