Datasheet

757
AT32UC3A
36.9.8 SYNC
This instruction allows external debuggers and testers to measure the ratio between the external
JTAG clock and the internal system clock. The SYNC data register is a 16-bit counter that
counts down to zero using the internal system clock. The busy bit stays high until the counter
reaches zero.
Starting in Run-Test/Idle, SYNC instruction is used in the following way:
1. Select the DR Scan path.
2. Scan in an 16-bit counter value.
3. Go to Update-DR and re-enter Select-DR Scan.
4. Scan out the busy bit, and retry until the busy bit clears.
5. Calculate an approximation to the internal clock speed using the elapsed time and the
counter value.
6. Return to Run-Test/Idle.
The full 16-bit counter value must be provided when starting the synch operation, or the result
will be undefined. When reading status, shifting may be terminated once the required number of
bits have been acquired.
36.9.9 AVR_RESET
This instruction allows a debugger or tester to directly control separate reset domains inside the
chip. The shift register contains one bit for each controllable reset domain. Setting a bit to one
resets that domain and holds it in reset. Setting a bit to zero releases the reset for that domain.
See the device specific documentation for the number of reset domains, and what these
domains are.
For any operation, all bits must be provided or the result will be undefined.
36.9.10 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
Table 36-12. SYNC_ACCESS details
Instructions Details
IR input value 10111 (0x17)
IR output value peb01
DR Size 16 bits
DR input value dddddddd dddddddd
DR output value xxxxxxxx xxxxxxeb
Table 36-13. AVR_RESET details
Instructions Details
IR input value 01100 (0x0C)
IR output value p0001
DR Size Device specific.
DR input value Device specific.
DR output value Device specific.
32058K
AVR32-01/12