Trying to dump flash memory through JTAG

Hi guys,

I´m trying to connect in an embedded system which uses BGA 28F128J3A flash. I bought a FT2232H mini module interface for JTAG connection. I wired up the four lines between target and interface.

Windows detects my interface as two USB serial ports without problems. I have used UrJtag program and Boundary Scan tool software. Both programs recognize my interface but when I try to go deeper and detect the flash from the unit it always says "TDO seems to be stuck at 1" and you can´t go further.

When I measure at four lines I get 3,3V, so it means high level which I guess it´s not nomal but I´m not sure. I don´t know if it has to do with the driver or there is some trick to avoid this situation.

May be some of you have worked with similar tool before and have some idea about the problem. Thanks.

Are you sure the jtag is connected only to that flash, and not daisy chained?

Hi Kubeek,

not sure about anything, no schematics, multilayer processor BGA board, but based on an SMD previous version I follow JTAG lines from the processor to a free connector and I guess it should use exactly the same pins. It seems the problem is from the interface and not from the equipment.