General Write Synchronization

Write-Synchronization is triggered by writing to a register in the peripheral clock domain (GCLK). The respective bit in the Synchronization Busy register (SYNCBUSY) will be set when the write-synchronization starts and cleared when the write-synchronization is complete. Refer also toSynchronization Delay.

When write-synchronization is ongoing for a register, any subsequent write attempts to this register will be discarded, and an error will be reported though the Peripheral Access Controller (PAC).


REGA, REGB are 8-bit core registers. REGC is a 16-bit core register.

Offset Register
0x00 REGA
0x01 REGB
0x02 REGC

Synchronization is per register, so multiple registers can be synchronized in parallel. Consequently, after REGA (8-bit access) was written, REGB (8-bit access) can be written immediately without error.

REGC (16-bit access) can be written without affecting REGA or REGB. If REGC is written to in two consecutive 8-bit accesses without waiting for synchronization, the second write attempt will be discarded and an error is generated through the PAC.

A 32-bit access to offset 0x00 will write all three registers. Note that REGA, REGB and REGC can be updated at different times because of independent write synchronization.