Programming P89C51RD2BA

[Singer]

Hi All,

Hoping you can help me out with a problem I'm having with Flash Magic. I'm having connectivity problem using ISP to program my board.  I know flash magic works because I used it on a couple boards previously but now for some reason I'm unable to connect anymore.  I have the following settings: COM 2, baud rate = 9600 bps, Device = 89C51RD2xx, Interface = None (ISP).    

I have checked that the upper case 'U' character is correctly echoed at 9600 bps but for some reason flash magic keeps throwing the "Unable to connect at the specified baud rate".  This suggests to me that my target boards is following the ISP protocol as outlined in the Manual for the P89C51RD2.  

Any ideas of why I can't connected.

[Andy Ayre]

I assume you can't even read the device signature. If so...

Start FM
Press F1 to enter debug mode ([Debug] appears at the top of the Window)
Chose ISP -> Read Device Signature...
Wait for the unable to connect message.
Press F2 to exit debug mode
Email me the debug file C:\flashmagic.fmd
Delete the debug file.

My email address is at the bottom of this post and in the Help -> About window.

[Andy Ayre]

Here was the problem:

"The signal ground to the PC was wired into Vcc
on the board. The boards Vcc is +8V which caused the PC to bias its
communication around that level.  I did notice that strangely the signal
output from the signal seemed to have a DC bias but being a firmware guy
I didn't clue in and since my board was receiving and echo back the
character it didn't occur to me that the received might be biased to +8V
and hence missing the bits.  The reason it worked before is that I had
the Vcc set to +7.5V which brings it very close to the cusp of the -3V
logic 1 threshold specified in RS-232. So on a good day the data would
be received on a bad day it wouldn't receive at all."