Date: Mon, 30 Jun 2008 21:26:52 +0200 From: Volker <volker@vwsoft.com> To: Rohit Grover <rgrover1@gmail.com> Cc: freebsd-embedded@freebsd.org Subject: Re: having trouble receiving serial data using my USB->serial adaptor Message-ID: <4869337C.6050105@vwsoft.com> In-Reply-To: <426bed110806300025j5a92080bx59cdb2248c77b8c0@mail.gmail.com> References: <426bed110806300025j5a92080bx59cdb2248c77b8c0@mail.gmail.com>
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On 12/23/-58 20:59, Rohit Grover wrote: > Hi, > > I am having trouble getting my BAFO 810 USB->serial adaptor to > work. I have built the uplcom and ucom drivers into the kernel, > and my USB->serial adaptor is recognized at boot, as can be > inferred from the following lines from /var/run/dmesg.boot: > > ucom0: <Prolific Technology Inc. USB-Serial Controller, class > 0/0, rev 1.10/3.\ 00, addr 2> on uhub3 > > I am using minicom to drive /dev/cuaU0 at 115200 8N1. > > If I connect the Tx and Rx lines (pins 2 and 3) of the DB9 > connector, I can get echoes of my keystrokes on the minicom > terminal. > > Unfortunately, I am unable to connect to an embedded device which > supports serial connections at 115200 8N1. When I plug the serial > output connector of my adaptor to a NULL modem and then to the > target embedded system, I don't see any serial output from the > device on my minicom terminal. This same device communicates > correctly with the serial port of my linux desktop with minicom > and 115200 8N1. > > As a further experiment, I manually connected pins 2,3, and 5 of > the serial end of my adaptor to pins 3,2, and 5 respectively of > the embedded device, but still no luck. > > What am I missing? > > regards, > Rohit, hard to tell on the distance but if you're able to receive (using a loopback adapter), it sounds like either side is most likely requiring hardware handshake (DSR/DTR, RTS/CTS). Sometimes it helps to short cut the DCD line (to RTS/DSR), as some device refuse to send if DCD is not set. If you're owning a break out box, it should be snap to figure that out. At least you should check using a serial line tester (those little tools signaling line status using LEDs or use a Voltmeter to check for correct line status). Volker
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