I accidently set the security bit. Jtag stopped working. I tried to erase the flash by doing the follow:

1. TST=0,
2. ERASE=1.

But jtag still complaining no device found.

What is the correct procedure to clear the security bit, or erase the whole flash so jtag will work again?

thanks

Power off the board.

Disconnect TST (should internally pull low, normally disconnected)
Set ERASE to VCC (3V3)

Power on board.

Wait a second (at least 10ms).

Power off board

Pull ERASE low (external 10K to GND)

Following contains schematic for AT91SAM7S-EK
http://www.atmel.com/dyn/resources/prod ... oc6112.pdf

Powering on with TST at VCC (plus several other GPIO's high) for 10 seconds will write the default SAM-BA loader into flash.

I did set ERASE to high, TST unconnected. the flash is erased b the security bit is still set. I still cannot use the segger/iar jtag. Complaining it cannot find any device on the chain.