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Hello Ezra,

I am using ICP-ISP bridge code v16. I hope you are using same. I am using LPC932 on MCB900 to hold the bridge.

My T1 & T2 are 100msec.

In VDD circuit of ICP-method, if you use one npn Tr then Vdd drops below 2.7v (3.3-0.65). Brownout protection becomes active as all fresh chips are brown-out enabled. You need to use npn-pnp pair, so voltage remains near 3.1V. Or you can use MOS-Tr, if you know the technique.

I have MCB900v4 PCB. Circuit attached. Circuit slighly differs from PCB V1 to V4. Although 6VDC should be OK, MCB900 behaviour is TYPICAL. I am using 5V regulated Linear PSU for powering up through jack. But its better to use give power through 2pin relimate connector marked VIN near 9pin connector.

Also check version of LPC9xx you are trying to program, as some of them support only ISP!, I read somewhere.

I hope this helps.

With warm regards.

Yours truly,
Hitesh Mahant
www.vital4all.com

PROGRESS of your life depends only on SIZE and QUALITY of your Goals. And the secret of success achieving them is "How discipliend YOU ARE".

Check your power supply.

I also faced same problem of getting all FFs. Intitially I used a 5V/1A SMPS, where problem was more frequent. i.e. 8/10 times I was getting FFs. Then I changed to a linear PSU of 5V/500mA. The problem reduced to 2/10. (Current rating  is not ciritical.)

I also noticed that  it works best, if I hold eliminator PIN tight and perform  read signature / program the device.I now need to change the PIN of PSU and the socket on MCB board, and install matching pair with good contacts.

hope this helps.Andrew Ayre wrote:

Hitesh

Hello Andy,

I have got some LPC922FN-CC3887 in DIP. I got them from local a supplier.
These have same behaviour. They program only once in ISP mode, whatever simple and smallest TEST code I write!

So I decided to try ICP method. On MCB900 with LPC932 in socket , I loaded ISP-ISP bridge (v16).  With ckt given (with slight modification) all of them worked for multiple programming; even those I doubted will never be usable again!

I made one change in Vdd ckt. Instead of single npn, I used npn-pnp pair in Vdd ckt to get better Vdd for target CPU.

With warm regrds,
Hitesh