LPC931 not working after adding anotehr 3.3V device

[kasd]

My LPC930 programming (using the UART Rxd and Txd with Flash magic)  to program my old target with LPC930 as the only 3.3V device. After I add another 3.3V device to the same board, the programming does not work.

It is found that the LPC930 UART receive is not being driven to required 3.3V at HIGH. It is ~~2V only. So I power up the target board and then program it. It is able to program.

But if I try to re-program the same target with another hex file using the same method as above (ie powering up the target first), it does not work. It still does not work without powering the target. Anyone encounter such a problem.

The programming tool I am using is self-built board with circuitry using the same as the MCB900. It is able to work because it can program the MCU without another 3.3V device connected to the target.

[erikm]

This "stinks" power supply overload

Erik

[kasd]

but I have pump a direct 3.3V on the programming tool and then the result is the same.