AP1616

The AP1616 is designed as the software modifications of register WDTCON. Software modifications of register WDTCON may be performed at any time during program execution, however, modifications of WDTIN and WDTREL will become effective at different times.

A change of bit WDTIN will immediately (at the end of the execute phase of the instruction which writes to WDTCON) switch the clock input for the Watchdog Timer to the selected prescaled CPU clock. This means that when changing WDTIN from 0 to 1 (fast to slow clock), the Watchdog Timer will get the next clock tick within the next 0 .. 1024 TCL. When changing WDTIN from 1 to 0 (slow to fast clock), the Watchdog Timer AP1616 will get the next clock tick within the next 0 .. 4 TCL.

When bit field WDTREL is modified, the new value will not be transferred into the high byte of WDT until either the Watchdog Timer overflows or the SRVWDT (Service Watchdog Timer) instruction is executed. Therefore, if an immediate transfer of WDTREL into the high byte of WDT is desired, SRVWDT must be executed after WDTREL has been written to WDTCON. If you want to know more information such as the electrical characteristics about the AP1616, please download the datasheet in www.seekic.com or www.chinaicmart.com .