Re: Programming the external flash in a ROMless microcontroller (NXP

Started by Stephen Pelc December 7, 2007
From: Deven Topiwala

> LH79520 is a ROMless device (at least the one from NXP does not have
> in-built flash, the sharp device has some in-built flash).

> How do I write the program in the flash?

Because most Flash is soldered to the board, the usual way is to
use a JTAG device to connect to the CPU and to waggle the
address, data and control lines. This is usually very slow.

On an ARM, you can download Flash programming code into RAM
through JTAG, and then run it while providing data through the
JTAG link. This is much faster.

Nearly all ARM JTAG units will talk to nearly all ARM7 cores, as
they mostly use the same debug unit. You may find one that
supports your combination of CPU and Flash. Otherwise you will
have to write the Flash driver yourself.

For a JTAG unit that is completely user programmable, and
includes an ARM debugger, assembler and disassembler, see:

Stephen Pelc,
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: - free VFX Forth downloads

An Engineer's Guide to the LPC2100 Series