SLAU320AJ July 2010 – May 2021
Devices that support protection by user password can be unlocked by providing the correct password. To unlock the device, the JTAG mailbox is used in combination with the device BootCode.
To activate the password unlock mechanism, the password exchange request (0x1E1E) must be applied to the device (see the detailed sequence diagram below).
After executing the password exchange request, there is a timeslot of only 1.2 s to apply the correct password. If the password is not applied during this time frame or if the password is wrong, a BOR event is executed by the device.
Initialize JTAG access (ResetTAP) and hold device in RESET | ||||
IR_Shift(IR_JMB_EXCHANGE) | :do JTAG mailbox exchange request | |||
DR_Shift16(0x0011) | :configure JTAG mailbox to 32-bit mode | |||
DR_Shift16(0xA55A) | :send device after BootCode execution into LPM4 | |||
DR_Shift16(0x1E1E) | :perform password exchange request | |||
Stop JTAG (release and run device) | ||||
Wait until BootCode is executed and device is in LPM4 | ||||
Initialize JTAG access (ResetTAP) | ||||
IR_Shift(IR_JMB_EXCHANGE) | :do JTAG mailbox exchange request | |||
DR_Shift16(0x0001) | :configure JTAG mailbox to 16-bit mode | |||
DR_Shift16(password[i]) | :configure JTAG mailbox to 16-bit mode | Repeat for password length |