Can not program device

[Sergy]

Hi,

I have 2 pins that connected to transistors that turn on high-side FETs. One turns on 3.3v for the rest of the system and another one 4v.

When I turn on 3.3v everything is fine, but when I turn on 4v I can not reprogram device anymore in Keil - says Device not found.

4v lines (controlled by P0.05) do not even cross SWCLK or SWDIO lines. What could be the problem?

Device continues to operate properly, just cant do anything with the debugger.

Also eventually after a while i can reprogram the device (after i completely power it off, disconnect JTAG and UART-USB!!!).

Any idea what could be the problem?

Thanks!

[Sergy]

Hello Hung, it has SD programmed on it, but it doesnt use it and yes GSM has about 1.6A peak current.