problem with serial - usb

[arjun mitra]

Hi,
Im a 7th sem electrical engineering student. I recently made a pc interfaced p89c51rd2bn programming circuit using max232 for the serial interface.All was well when i was using the serial port of a p.c.But when i tried programming the circuit using a laptop( with a usb to com cable), i cannot establish communication. when insert the cable into the usb port, the laptop says it has been installed automatically. But as you know flash magic uses the com port as an i/o interface. So how do i establish communication and ultimately program my circuit using this usb to com port cable. Do i change any settings of flash magic? Is there any way of tinkering with the software to prompt communication via a usb-serial port.
Thanks
Arjun

[Andy Ayre]

The USB cable driver must install so it appears as a regular COM Port. Check that it appears as a COM port under the device manager and note the port number (which may not be what you expect).

If the cable appears as COM port and you still cannot get it to work try using Hyperterminal to make sure the cable and driver works.

[Tushar Jagad]

Hey,

I too have tried the same. I got a USB-RS232 from Intex and after installing the drivers i get COM4 as my virtual serial port.

If I try to communicate with my circuit on the laptop using Flash Magic it fails to communicate with it. But if i program the controller on the PC and connect the circuit to the laptop then hyperterminal is able to communicate with it whereas Flash Magic fails to do the same.

I am using the Flash Magic v2.34 and WinXP as my OS.

Thanx,
Tushar

[Andy Ayre]

Are you using DTR and RTS at all? If so try increasing the values of T1 and T2 in the advanced options. If not then I would check using a scope the actual baud rate of the 'U' being sent to the device to autobaud, when using the cable. Is it what you are expecting?