0-255 adder missing integer 17 and 19?

peepo

prolly not exactly what you were hoping for, in the way of code....
but I seem to have run out of ideas....

expected function: to send integer 0 to 255 repeatedly over uart
actual: 0 to 255 repeatedly, but missing integers 17 and 19 only.
I have built and run this a number of times, results always identical.


based on: http://hamsterworks.co.nz/mediawiki/index.php/Module_16

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

entity top_level is
    Port ( clk_50MHz : in  STD_LOGIC; -- FPGA's external oscillator
                data_out : out std_logic
    );
end top_level;

architecture Structural of top_level is

   signal busyshiftreg : std_logic_vector(9 downto 0) := (others => '0');
   signal datashiftreg : std_logic_vector(9 downto 0) := (others => '1');
   signal counter : std_logic_vector(12 downto 0) := (others => '0');
    signal shiftreg : std_logic_vector(7 downto 0) := "00000000";
   
begin

data_out <= datashiftreg(0);

uart_out : process (clk_50MHz) is
begin
    if rising_edge(clk_50MHz) then
        if busyshiftreg(0) = '0' then 
            busyshiftreg <= (others => '1');
            datashiftreg <= '1' & shiftreg & '0';
            shiftreg <= shiftreg + 1;
        elsif counter = 5207 then  -- 9600 baud
            datashiftreg <= '1' & datashiftreg(9 downto 1);
            busyshiftreg <= '0' & busyshiftreg(9 downto 1);
            counter <= (others => '0');
        else
            counter <= counter+1;
        end if;
    end if;
end process;
 
end Structural;

jpiat

There is no obvious reason I can think of ... Is the tx output wired to a pc/raspberry/microcontroller ? The only reason I can imagine is a baudrate mismatch or that those two values have a typical waveform that can make them misinterpreted by receiver. Do you receive nothing when those values are sent or some garbage ?

peepo

LogiPi is attached to RPi as normal

nothing is output to console, see end for edited copy
all other integers are present.

.ucf
NET "clk_50MHz" LOC = P85;  #50Mhz
NET "data_out" LOC = P82; #TX


read_uart:

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>


int main(int argc, char ** argv) {
  int fd;
struct termios options;
tcgetattr(fd, &options);
cfsetispeed(&options, B9600); //B115200);
cfsetospeed(&options, B9600); //B115200);
tcflush(fd, TCIFLUSH);
tcsetattr(fd, TCSANOW, &options);

  // Open the Port. We want read/write, no "controlling tty" status, and open it no matter what state DCD is in
  fd = open("/dev/ttyAMA0", O_RDONLY | O_NOCTTY | O_NDELAY);
  if (fd == -1) {
    perror("open_port: Unable to open /dev/ttyAMA0 - ");
    return(-1);
  }

  // Turn off blocking for reads, use (fd, F_SETFL, FNDELAY) if you want that
  fcntl(fd, F_SETFL, 0);
  char buffer[1];

  while(1) {
    int  n = read(fd, (void*)buffer, 1);
    if (n < 0) {
      perror("Read failed - ");
      return -1;
    } else if (n == 0) printf("."); //printf("No data on port\n");
    else {
      buffer[n] = '\0';
      printf("%d\n",buffer[0]);
      fflush(stdout);
    }
  }
  close(fd);
  return 0;
}

254
255
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
21
22
23

peepo

minicom -b 9600 -o -D /dev/ttyAMA0 rtscts
wfm
see: http://en.m.wikipedia.org/wiki/Software_flow_control

I did not yet find a way using termios

courtesy Hamsterworks!

tx

~:"
 

jpiat

I would never have think of this ! This means that termios has XON/XOFF enabled by default ... there must be some way of disabling it by software.

Hamster

Hi,

This code is how I do it (open port, set speed, set flow control)...

/********************************************************************/
static int openSerialPort(char *fname)
{
    int f, flags;
    struct termios cf;
    f = open(fname, O_RDWR);
    if (f == -1)
    {
        fprintf(stderr, "Unable to open '%s'\n", fname);
        return -1;
    }
    if (tcgetattr(f, &cf) == -1)
    {
        fprintf(stderr, "Unable to get termios details\n");
        close(f);
        return -1;
    }
    if (cfsetispeed(&cf, B19200) == -1 || cfsetospeed(&cf, B19200) == -1)
    {
        fprintf(stderr, "Unable to set speed\n");
        close(f);
        return -1;
    }

    /* Make it a raw stream and turn off software flow control */
    cfmakeraw(&cf);
    cf.c_iflag &= ~(IXON | IXOFF | IXANY);
    if (tcsetattr(f, TCSANOW, &cf) == -1)
    {
        fprintf(stderr, "Unable to set termios details\n");
        close(f);
        return -1;
    }
    if (-1 == (flags = fcntl(f, F_GETFL, 0)))
        flags = 0;
    if (-1 == fcntl(f, F_SETFL, flags | O_NONBLOCK))
    {
        fprintf(stderr, "Unable to set non-blocking\n");
        close(f);
        return -1;
    }
    return f;
}

peepo

I had tried IXON | IXOFF | IXANY without success, will give it another hack....

tx

~:"