Hi Andrea,
the meaning of the connection between PB4, PB6 and PB7 and three FPGA
pins and J3 is to have more flexibility if you need to have more
auxiliary lines from the Fox and the FPGA . You can avoid to pull out
R30, R33 and R34 (that would be quite irreversible since the little size
of those resistors in package 0402) simply programming in input the PB4,
PB6 and PB7 lines.
If you run the command "readbits" from the Fox console or telnet or ssh
session you can see an output like this:
111XXX1X XX00XXX1 XXXXXXX11111111101101111XX111111
The mid part: XX00XXX1 is the input from portB where 1 is PB0. So you
can see that in my board PB4 is an input, PB6 and PB7 are output since
they show a "X" as input.
All you have to do is to program in input those lines with simple IOCTLs
with a simple program like this:
#include "stdio.h"
#include "stdlib.h"
#include "unistd.h"
#include "sys/ioctl.h"
#include "fcntl.h"
#include "linux/gpio_syscalls.h"
int main(int argc, char **argv) {
// set PB4 as input
gpiosetdir(PORTB, DIRIN, PB4);
// set PB6 as input
gpiosetdir(PORTB, DIRIN, PB6);
// set PB7 as input
gpiosetdir(PORTB, DIRIN, PB7);
return(0);
}
After the program run the command readbits will show the lines PB4, PB6
and PB7 as inputs with their actual logic values instead of "X".
Please tell me if you need more advise on that.
Roberto Asquini
andrea.maccaferri ha scritto:
>
> I'm trying to use the foxvhdl board & foxboard alltoghether.
> I need to use quite all j3 pin as input to fpga.
> I need to built 28 counters to count input pulse during
> a sample time programmable.
> So I have a 5Mhz clock input as clock for my sample interval,
> a synch 1hz pulse to synchronize my internal time base, and 28 input
> signal to be counted, so I'm quite short on input available.
> All work correct except that pin JP3.3 and JP3.4 looks as there is
> an electrical conflict on them and input counted on them are wrong,
> sometimes more then expected, sometime less then expected.
> Looking to electrical schematics of foxvhdl it looks that a conection
> to PB4, PB6 and PB7 is present on JP3.3, JP3.4 and JP3.5.
> Which is the function of this connection ?
> May I remove R30, R34 and R33 to remove the conflict?
>
> best regards
>
> Andrea Maccaferri
>
>
>
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Roberto Asquini
Acme Systems srl
[EMAIL PROTECTED]
http://www.acmesystems.it
