Problem with loading hex files to DS89C420 ISP pins

DS89C420 ISP problem

I have a 420 board with some SRAM and other bits on it. The ISP pins are hard wired ( RST to VCC, EA,PSEN to gnd) so I can just program the chip.
I can logon to the 420 loader ( using the 420 0.04Beta software from the www), I can erase the device and get 4400 CRC . I can display memory contents. When loading a small Hex file,(200 bytes) I see % loaded + errors.Sometimes I get "loading done"( x errors) sometimes , with another file , I get "invalid hex file" errors.
On loading the small hex file, I get 1A C0 for the first two bytes instead of 02 04.This seems to be 100% consistent although the number of errors and % loaded seems to vary.The hex files load correctly into our other programmers.

I have tried various baud rates ( down to 9600) and both hardware/ XonXoff protocols with no difference.
I can get it to do the same thing with Hyperterminal, but what is the syntax for loading a hex file . The manual says "L" or "LX" but what do I have to do to get the hex file transmitted?
I'm really stuck.
Any ideas greatfully received.

Re: DS89C420 ISP problem

Hi,
I used the programming utility from dallas, and I had some kind of similar problems, like yours. I did not figured entirely from where the problem was, but a substantial decrease of error number was observed after I improved the quality of my power supply. Check your power supply, to be 5v, noise as low as possible, and put a large tantalum cap (100-470uF) near the chip, along with 100nF near each vcc pin.

Re: DS89C420 ISP problem

1. Are you sure you are using the correct HEX file?
2. L commadn in the Hyperterminal then choose send text file.
3. Be sure to erase it first using the K command before using the L command.
4. Series of G's will come out as a feedback for correct transmission of program.
5. The program MTK has some bugs if you do not have a capacitor in your reset and a resistor.
6. Be sure you are supplying enough power to the chip.

If any other problem arises, contact me.

Re: DS89C420 ISP problem

Just additional, what is the use of SRAM? are you loading the file in the SRAm or FLASH?

Re: DS89C420 ISP problem

I fixed it....... Dallas Semi sent me this link **broken link removed** and suggested I use the KTK software .

Now it works 100%. It still doesn't work using loader.exe but I don't care.
Thanks for your replies.

SRAM is for data storage only.A large array. program is loaded into on-board Flash.