Lpc2000

"rattencremesuppe" <tricknology@...> writes:

> I'm using a TinyARM eval board which worked fine with a 10MHz crystal.
> Then we replaced it with a 3.6864MHz crystal and now Philips Flash
> utility says that it can't connect to the test board.

Everyone agrees, apparently, that we need at least a 10 MHz crystal.
That's too bad.  

I've had in mind the idea of "de-tuning" the LPC210x to make it somewhat
of a PIC or MSP430 replacement.  I find the ARM much more pleasant to
program than the PIC and it would be nice to stick with a single CPU and
instruction set etc. etc. ("one size fits all").  Of course, the power
supply and sometimes the clock will still be more complicated than with
the PIC.

I'm using Martin Maurer's lpc21isp program from

   http://www.engelschall.com/~martin/lpc21xx/isp/index.html

as the bootloader running under Linux.  Here is the command I use with
my Olimex LPC2106 board with a 14.7456 MHz crystal:

     lpc21isp -bin combo.bin /dev/ttyS0 115200 14746

So, your crystal at 3.6864 MHz is exactly one fourth that speed.  I
wonder if you could use either the Philips bootloader or the Maurer
bootloader and /say/ the crystal speed is 14746 even though it is only a
quarter of that.  The bootloader (at least Maurer's) might not actually
set the serial port speed, I'm not sure.  In which case you might really
set the serial port speed to 9600 but say the baud rate is 38400, e.g.

     lpc21isp -bin combo.bin /dev/ttyS0 38400 14746

There might be some way to trick the bootloader and the chip into
programming the Flash.  Perhaps the Flash time periods would then be
off.  It might still work.

I think the source is available for Maurer's bootloader, so if it does
set the serial speed, we might be able to change it to set it to one
quarter of what it will tell the LPC chip.

I hope you will experiment further and let me know how it all works out.

Another possibility might be to have two clock sources.  A fast one used
just to do the initial programming of a custom bootloader (or perhaps
used everytime you program the Flash) and a slow one for normal use to
conserve power.  Just a thought.


-- 
Frank