Datasheet

712
32133D–11/2011
UC3D
31.6.3.9 CHIP_ERASE
This instruction allows a programmer to completely erase all nonvolatile memories in a chip.
This will also clear any security bits that are set, so the device can be accessed normally. In
devices without non-volatile memories this instruction does nothing, and appears to complete
immediately.
The erasing of non-volatile memories starts as soon as the CHIP_ERASE instruction is selected.
The CHIP_ERASE instruction selects a 1 bit bypass data register.
A chip erase operation should be performed as:
1. Reset the system and stop the CPU from executing.
2. Select the IR Scan path.
3. In Capture-IR: The IR output value is latched into the shift register.
4. In Shift-IR: The instruction register is shifted by the TCK input.
5. Check the busy bit that was scanned out during Shift-IR. If the busy bit was set goto 2.
6. Return to Run-Test/Idle.
31.6.3.10 HALT
This instruction allows a programmer to easily stop the CPU to ensure that it does not execute
invalid code during programming.
This instruction selects a 1-bit halt register. Setting this bit to one resets the device and halts the
CPU. Setting this bit to zero resets the device and releases the CPU to run normally. The value
shifted out from the data register is one if the CPU is halted.
The HALT instruction can be used in the following way:
1. Select the IR Scan path.
2. In Capture-IR: The IR output value is latched into the shift register.
3. In Shift-IR: The instruction register is shifted by the TCK input.
4. Return to Run-Test/Idle.
5. Select the DR Scan path.
DR Size Device specific.
DR input value Device specific.
DR output value Device specific.
Table 31-55. AVR_RESET Details (Continued)
Instructions Details
Table 31-56. CHIP_ERASE Details
Instructions Details
IR input value 01111 (0x0F)
IR output value
p0b01
Where b is the
busy bit.
DR Size 1 bit
DR input value x
DR output value 0