Messages

> Devices come from the factory so they reset into ISP mode - i.e. the status
> bit is set. Only after you have programmed them for the first time are you
> really testing your ISP entry method.

Yes, I noticed that :-)


> Therefore I suggest you download the Flash Magic application note on ISP
> entry using the handskaking signals. In there is a description of the MCB900
> circuit with waveforms. You can use this to debug it.

Allready got that and used it as a basis for my own adapter board
that goes in between the PC serialport and the application board.


> The pulses are very fast - too fast to see on an LED. You need an
> oscilloscope.

As I wrote in an earlier posting, I did not see the pulses with the scope.
Now I soldered a new lpc935 on the app. board and FM v3 can at least
read the bits and all by selecting an option out of the ISP pulldown menu.

roelof

So now I replaced the lpc935 with a fresh one and FM is once
again detecting and reading the uC :-)

But it still leaves me with the question what I did wrong in the
first programming cycle with FM and the lpc935.
As it appears to me that the complete bootloader is gone
from flash and I do not have a way to check it. I mean I do
not have a suitable parallel programmer that can handle
the lpc935.

Now I have to figure out how to get back in to the bootloader
reliable after programming even with non working code.

roelof

Well the rs232<->ttl level converter is there, it is the sp3223 from Sipex.
I meant the negative voltages on the NOR gate inputs. Sorry, I did not
make that very clear.

Even with a scope I did not see the pulses. I also adjusted the 120 ms
to 1 sec orso, but that must mean the time between the pulses :-(

No notouch anymore possible, so I have to desolder the lpc935 and
exchange it with a working/fresh one.

Thanks.

roelof

Hi all,

I am new to this forum and offcourse I do have a question.

I have made a pcb with a 89lpc935 on it. This uC should
be programmed by means of ISP. I have shameless copied
the mcb900 circuit and adapted it at some points to counter
negative voltages produced by the PC serialport. The dtr and
rts line do control resp. the power and reset line.
I put some LEDs on the pcd to see what is going on.

Now the problem : I can not initialize the flash embedded
bootloader anymore. Apparently the first time it worked
and I could program (some non working) code into flash.
But now it is dead even when I manually try to get the lpc935
into bootloader mode. No reaction after sending "U" :-(
So the bootvector and or the bootstatus bit is upset.

In my trials to get things working again I noticed the LED which
is connected to the rts (reset) line. It does not toggle three
times after pushing the start button in FM. This also goes for
the LED which is connected to the rxd line (data from the PC).

Is this observation correct ?

Is there another way to get the bootloader going except for
the notouch method ?

TIA,

roelof