---------- Forwarded Message ----------
Subject: opening device given its serial and hardware flow control
Date: Tuesday, 10. February 2009
From: "frrrt_" <frrrt_@xxxxxxxxxxxxx>
To: opensource@xxxxxxxxxxxxx
Dear libftdi developers,
I wrote (based on a couple of examples seen online) a little test/demo
program which features two threads: read (continually reads FTDI device)
and write (continually writes random numbers to FTDI device).
I run this program with a FTDI USB cable
http://www.ftdichip.com/Documents/DataSheets/Modules/DS_TTL-232R_CABLES_V201.pdf
with TX connected to RX and ideally RTS connected to CTS doing a
hardware flow control communication between the two aforementioned threads.
However I am stepping into a couple of errors detailed below, which I
hope somebody could help me with please?
See attached readwrite.c
Cheers,
Luca
1. Cant open specific FTDI device with serial D44F6D5
tried with ftdi_usb_open_desc(&ctx, vendor, device, NULL,
"D44F6D5");
and also with ftdi_usb_open_desc(&ctx, vendor, device,
"TTL232R-3V3", "D44F6D5");
If I am logged in as root
init: OK
open: rv=-3, error=device not found, errno=Inappropriate ioctl for
device (25)
If I am logged in as a user
init: OK
open: rv=-3, error=device not found, errno=Operation not permitted (1)
2. Can't get to use handshaking signals RTS and CTS (hardware flow)
Either I connect RTS and CTS together or leave them floating, it
reads 0 for about 5 seconds
then I get following error: (basically it times out after so many
write attempts)
write: rv=-110, error=usb bulk write failed, errno=Resource
temporarily unavailable (11)
close: rv=0, error=usb bulk write failed, errno=Resource
temporarily unavailable (11)
If I manually connect CTS to GND then everything works and I
receive the random numbers. Sounds like FTDI device never
sets RTS(ready to send) to GND. I don't understand this because,
from what I have gathered
googling hardware flow control, CTS line should be high (+3.3V) for
source device to begin transmission
The same happens regardless I set bitbang ON or OFF
-------------------------------------------------------
--
libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
To unsubscribe send a mail to libftdi+unsubscribe@xxxxxxxxxxxxxxxxxxxxxxx //
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation.
//
// Example of pthread read and pthread write inspired by
//
// sertest.c Copyright (c) 2006 Dave Hylands <dhylands@xxxxxxxxx>
// testusb.c Copyright (c) 06/2004 by Wolfgang Wieser
//
// This program is meant to be run on a FTDI device with RX connected to TX and
// CTS connected to RTS (hardware flow control)
//
// ________
// |
// TX |--->
// | |
// RX |<---
// |
// |
// RTS |--->
// | |
// CTS |<---
// |
// ________|
//
// From my understanding of RS232 gathered from internet and books the
following should happen:
//
// RTS goes high whenever the device is ready to receive
//
// CTS high allows device to begin transmission
//
//---------------------------------------------------------------------------------
//
// USAGE
// go to directory
// /home/duffyduck/new_ftdi_driver/my_example2
//
// compile with the following
// gcc -O readwrite.c -o readwrite /usr/local/lib/libftdi.a -W -Wall -Wformat
/usr/lib/libusb.a -pthread
//
//---------------------------------------------------------------------------------
//
// PROBLEMS SEEN SO FAR
//
//
//
// 1. Cant open specific FTDI device with serial D44F6D5
// tried with ftdi_usb_open_desc(&ctx, vendor, device, NULL,
"D44F6D5");
// and also with ftdi_usb_open_desc(&ctx, vendor, device,
"TTL232R-3V3", "D44F6D5");
//
// If I am logged in as root
// init: OK
// open: rv=-3, error=device not found, errno=Inappropriate ioctl for
device (25)
//
// If I am logged in as a user
// init: OK
// open: rv=-3, error=device not found, errno=Operation not permitted (1)
//
//
//
// 2. Can't get to use handshaking signals RTS and CTS (hardware flow)
// Either I connect RTS and CTS together or leave them floating, it reads 0 for
about 5 seconds
// then I get following error
// write: rv=-110, error=usb bulk write failed, errno=Resource temporarily
unavailable (11)
// close: rv=0, error=usb bulk write failed, errno=Resource temporarily
unavailable (11)
//
// If I manually connect CTS to GND then everything works and I receive the
random numbers. Sounds like FTDI device never
// sets RTS(ready to send) to GND. I don't understand this because, from what I
have gathered
// googling hardware flow control, CTS line should be high (+3.3V) for source
device to begin trasmission
//
// The same happens regardles I set bitbang ON or OFF
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/unistd.h>
#include <pthread.h>
#include <getopt.h>
//#include <termios.h>
//testusb
#include "ftdi.h"
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
//#include <sys/time.h>
//#include <time.h>
struct ftdi_context ctx;
static void Error(const char *where,int rv,struct ftdi_context *ctx,int doclose)
{
if(rv)
{
fprintf(stderr,"%s: rv=%d, error=%s, errno=%s (%d)\n",
where,rv,ctx->error_str,strerror(errno),errno);
if(doclose)
{
rv=ftdi_usb_close(ctx);
fprintf(stderr,"close: rv=%d, error=%s, errno=%s
(%d)\n",
rv,ctx->error_str,strerror(errno),errno);
}
ftdi_deinit(ctx);
exit(1);
}
else
fprintf(stderr,"%s: OK\n",where);
}
////////////////////////////////////////////////////////////
//
// Thread which processes the incoming serial data.
//
void *ReaderThread( )
{
int rv;
int i;
const int bufsize = 32;
unsigned char buf[bufsize];
printf("\nEntered ReaderThread \n");
while ( 1 )
{
rv=ftdi_read_data(&ctx,buf,bufsize);
if(rv<0) Error("read",rv,&ctx,1);
else
{
printf("%3d: ",rv);
for(i=0; i<rv; i++)
printf("%02x%s",buf[i],i%8==7 ? i%16==15 ? "\n " : " " : " ");
}
printf("\n"); fflush(stdout);
}
return 0;
} // ReaderThread
////////////////////////////////////////////////////////////
//
// Thread which writes serial data.
//
void *WriterThread( )
{
int rv;
int i;
const int bufsize = 16;
unsigned char buf[bufsize];
printf("\nEntered WriterThread \n");
//Fill TX buffer with some stuff
for (i=0; i<bufsize; i++) {
//buf[i] = 'c';
// buf[i] = i;
buf[i] = random();
}
while ( 1 )
{
//Fill TX buffer with some stuff
for (i=0; i<bufsize; i++) {
// buf[i] = 'c';
// buf[i] = i;
buf[i] = random();
}
rv=ftdi_write_data(&ctx,buf,bufsize);
if(rv<0) Error("write",rv,&ctx,1);
}
return 0;
} // WriterThread
////////////////////////////////////////////////////////////
//
// Main
//
int main() {
int rv;
int vendor=0x0403;
int device=0x6001;
int rc;
pthread_t readerThreadId;
// Initialize
rv=ftdi_init(&ctx);
Error("init",rv,&ctx,0);
// Open FTDI device with serial D44F6D5
//rv=ftdi_usb_open_desc(&ctx, vendor, device, NULL , "D44F6D5");
//rv=ftdi_usb_open_desc(&ctx, vendor, device, NULL , NULL);
//rv=ftdi_usb_open_desc(&ctx, vendor, device, "TTL232R-3V3", "NULL");
rv=ftdi_usb_open(&ctx,vendor,device);
Error("open",rv,&ctx,0);
// Reset
rv=ftdi_usb_reset(&ctx);
Error("reset",rv,&ctx,1);
// Disable bitbang: will need the handshake lines connected or nothing will
happen (short RTS and CTS)
// Comment read in testusb.c
//...With bitbang mode disabled, hence you need to use the handshake
signals. Otherwise, sending
// will stop with timeout and receiving will continuously read chunks of
length 0
rv=ftdi_disable_bitbang(&ctx);
Error("bitbang(off)",rv,&ctx,1);
// Set baudrate to 115200
rv=ftdi_set_baudrate(&ctx,115200);
Error("baudrate",rv,&ctx,1);
// Set hardware flow control
rv=ftdi_setflowctrl(&ctx,SIO_RTS_CTS_HS);
//rv=ftdi_setflowctrl(&ctx,SIO_XON_XOFF_HS);
Error("hardware_flow_control",rv,&ctx,1);
// Read out FTDIChip-ID of R type chips
if (ctx.type == TYPE_R) {
unsigned int chipid;
printf("ftdi_read_chipid: %d\n", ftdi_read_chipid(&ctx, &chipid));
printf("FTDI chipid: %X\n", chipid);
}
//Kick off read thread
rc = pthread_create( &readerThreadId, NULL, ReaderThread, NULL );
if ( rc != 0 ) {
fprintf( stderr, "Error creating ReaderThread: %s\n", strerror( rc ));
exit( 7 );
}
printf("\nInside main function after kicking off ReaderThread \n");
//Kick off write thread
rc = pthread_create( &readerThreadId, NULL, WriterThread, NULL );
if ( rc != 0 ) {
fprintf( stderr, "Error creating WriterThread: %s\n", strerror( rc ));
exit( 7 );
}
printf("\nInside main function after kicking off WriterThread \n");
//for(i=0; i<10; i++) {
//sleep(1);
//}
//keep main alive
while ( 1 ) {
}
}
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