Can programm my MCU only one Time (LPC935()

[tuxilein]

Hey,

i use Flash Magic Programmer a long time ago. I have had no problem with reprogramming the Device. Now i start to programm a device and it is done but i will reporgramm the same device nothing go.
I have not change any values it is all the same as before.

Flash magic can not conect after programing to the device. But the device is running.

Thanks

[Andy Ayre]

Which ISP entry method are you using?

What tests have you performed to determine the ISP entry method is working and what were the results?

[tuxilein]

"Use DTR and RTS to enter ISP mode"  if you mean this, i did'nt change everything.

now i have connnect a lcd display on the i2c bus and if it will programm secound time any data trash came.
this is only on some mcu's.

i can programm every mcu one time the next time i't don't will programm it.

thanks



Post Edited (09-20-06 13:45)

[Andy Ayre]

It sounds like your ISP entry method is not working. Use a scope to check the Rst and RxD pins and make sure you are seeing the three pulses. If you are not using an MCB900 then copy that circuit - it is the only one guaranteed to work.

[tuxilein]

mm i think you don't understand it.

my programmer circuit is ok and works good bevor. i use it over 2 years long now and i have net hed any problem with the programmer and reprogramming the mcu.

this problemm is now here. i can programm new mcu and the next time i didn't can programm it. noting change on the programmer hardware and no changes on the FM sw!

The circuit is from:
http://www.esacademy.com/software/flashmagic/appnotes/ISPHardwareEntryAppNote.pdf
site 5 and it works great. ok.

now you think after this the entry mode isn't ok?

thanks

[Andy Ayre]

So you have the same:

  - target board
  - microcontroller
  - version of Flash Magic
  - PC
  - serial cable

for the last two years, and it used to work but not you are having problems?

Something has changed. It's a matter of finding out what. Being able to program a brand new device once but then not being able to do it a second time is a classic symptom of failure to place the device into ISP mode.

[tuxilein]

ok thats right is all the same but the pc has changeed for 1,5 year but for a month i can programm with this.

yes i have now 12 devices that i can't programm again it was all new devices.

you have no idea what can change but the funny think is i can programm a new device one time and than is out to programm it.

[Andy Ayre]

So for the last month you were able to reprogram devices and then suddenly it stopped working with no changes to anything, including the hex file or version of Flash Magic?

Based on the limited information I have, I don't have any magic answers to your problem. In your situation I would do what probably most engineers would do and that is to throw away assumptions and start testing to build up a list of facts. If you want me to help you with that process, let me know.

[erikm]

my programmer circuit is ok and works good bevor. i use it over 2 years long now and i have net hed any problem with the programmer and reprogramming the mcu.

two possibilities

1) the most likely
The circuit is from:
http://www.esacademy.com/software/flashmagic/appnotes/ISPHardwareEntryAppNote.pdf
site 5 and it works great. ok.

you have substituted something and ended up with "a defective circuit that works"  such is VERY common and to make such show the problem can take something as simple as a change in temperature.  The callic is "My 232 inetrface is "tested and proven" now it does not work and after dragging along it is revealed that it does not work now because the PC was replaced.

2) something in your hardware is broken

Erik

[oarecare]

could it be that he has not selected 'erase blocks used by hex file' and the programs write on top of each other? just a guess... try to erase it fully and see if it works