MCP900 - Schematic - Does it Really work

[aquib]

Hi,

I am planning to build my own ISP programmer based on the MCP900 Schematic provided on the Keil Website.
I want to know what are the success ratio of my board working successfully. If I replicate the entire design will it surely work??

If anyone has a successful ISP design for the LPC9xx please forward it to aquibf at yahoo dot com

Cheers
Aquib 

[Je Gold]

Yes... if you  copy exactly as variation may introduce incorrect timing or voltages .....the RESET pin is pulsed in 50uS intervals.... any additional resistance or capacitance may throw the timing out.

Check your ISP waveforms against those in the flashmagic manual for the LPC900's.

All Vdd supply  lines need capacitor coupling..... however the "switched"  Vdd to the LPC900 micro will require quick rise times as per the data sheet for programming.

Joe

[aquib]

Hi Joe,
Thanks for the reply. In order to keep a the board resistance and capacitance low the PCB layout should be done meticulously.
Do you have any suggestions for the PCB layout for the MCP900 replica? Also a reference PCB layout would be good... do you know where I can get one.

Have you made your own ISP for the LPC9xx??

Cheers
Aquib

[erikm]

WHY?

The MCP900 cost (when shopping around) less than it will cost you to make your own.

Erik

[Je Gold]

1. MCB900 schematic
Yes, I have made the layout, nothing special just watch the lead lengths on the RESET line (because of the 50uS pulses)
(but naturally all lead lengths should be short as possible)

2. MCB900
Yes,  I agree  the MCB900  is very cheep... but cost of freight can be more than the MCB900 tool.

www.lpctools.com  for a low cost of $60 USD...  http://www.lpctools.com/index.asp?PageAction=VIEWCATS&Category=4

It is a  MCB900  not MCP900.

FDI has a very cheep programming tool also! 
http://www.teamfdi.com/USBDongle/usb-dongle.shtml   A small investment in tools can save hours of heart ache.

3. USEFUL INFO

There 3 methods of programming (+variants)
a) ISP programming via UART.... there are a few ways to get in to ISP.... but the hardware entry is 3pulse on the reset line immediately after POR (Power On Reset).... this is what MCB900 does quite cleverly.

Because it uses the UART a stable clock source is required - if you select an external clock source and no xtal or osc in connected the
the UART can not work and no ISP

b) ICP is real hardware level programming and the LPC900 micro is clocked by the external hardware.... you can recover from most situations to program the LPC900's/

However the hardware is a little more complicated  and 7pulses on RESET is required after POR.

The FDI tool does this/

c) Self Programming... or IAP   LPC900 code programs sections of the flash from code execution.

Complicated.... ask later.


Joe