Hello,
recently I changed to a new laptop (DELL M90) without RS232. I'm using monitor in ROM and the simulated serial interface for debugging. Everything is working fine if I'm using the integrated RS232 port of the docking station or one of the docking stations RS232-PCI card. But to be mobile I tried a Prolific USB-Serial converter and it fails. It was not very surprising me since we had different problems before (communication stops after some hours). Then I tried a 2x serial ExpressCard (NEWCARD-22020, with a 16C952 UART chip) but it also fails. After that I tried a small program with the bootstrap loader and it fails too. Sometimes the download starts, but the connection aborts after short time. May be a timing problem? I fiddled around with different FIFO parameters but was not successful.
Of course: I have checked all components with a terminal program.
Any ideas?
Hello!
Among some stuff I have tested last year I found the "PORT AUTHORITY USB SERIAL DB9 ADAPTER CABLE" is a very good one. Did you try this USB-RS232 adapter? Here is a link to see the stuff: www.cablestogo.com/product.asp Please note, this is not an advertisment, a reference guide only ;-).
It comes with drivers on CD. The only drawback I can remember is when I use FlashTool Beta from Phytec (http://www.phytec.com) to burn my f/w into a target, the tool slows down but still working. The FlashIt 8 (www.hse-electronics.com/) works just fine (besides its own glitches). Keil remote debugger runs smoothly w/ Authority cable. I use another virtual COM port at the same time, it also runs w/ no problem (I use an external USB hub).
My custom f/w works fine with s/w I wrote under LabWindowsCVI 8.0. However together w/ run-time DLL which come with newer CVI 8.5, it does malfunction (I did not dig a reason, just returned back to older 8.0). Should mention, e.g. the Quatech USB serial adapter QSU2-400 turned out to be a bad one, which fails when there is a small time gap between adjacent bytes in an incoming stream.
Seems to me, the cable I am talking about provides well tuned internal bufferization mechanizm (I did not touch default settings once it has been installed on my PC). It does work on my Dell laptop Latitute D610 where I had big problems with any kind of s/w with its internal RS232 in past.
As per my own experience, this is true: many USB-RS232 converters are bad, or either built-in port fails, or a laptop plugged into a docking station functions in a different way. You are not alone here.
Also, you may want to see the links: http://www.keil.com/forum/docs/thread11464.asp http://www.keil.com/forum/docs/thread11077.asp
Regards, Nikolay.
abouit USB-to_serial-converters and the conclusion was that most are not worth 1/10 the price.
The conclusion - if i recall correctly - was that only those based on the ftdi chip will work for debugging/ISP/ICP etc.
Erik
A lot of serial software expects/allows very short latencies. A USB-to-serial interface with a 256 character FIFO is very good at sending large blocks of data at a very high baudrate. But reacting to a one-character transmission timeout is not so easy...
Thank you for the hints. Latest news: I'm able to download, run and stop at brakepoints with the Prolific USB-RS232 converter (without using the FIFO). With the ExpressCard it is only possible to download. If I insert a breakpoint the communication stops. I will make further tests with PortMon and let you know the results.
By the way, the USB-RS232 adapter I was talking about and referred to as "PORT AUTHORITY" is actually being detected as Prolific manufacturer, and I use it on my Windows XP machine w/ Rx/TX FIFOs enabled and set to highest position.
--- Nikolay.