SX Embedded Controller Register

RTCC (Real Time Clock Counter)

Date Code(s): 9815, 9818, 9819, 9825, 9827, 9829, 9830, 9837, 9838, 9841, 9843, 9844, 9848: In Turbo mode, if the Prescaler is not assigned to the RTCC, the RTCC will not sense any external events. If the Prescaler is assigned to the RTCC, the RTCC works as an external event counter. With the Prescaler assigned to the WDT (Watchdog Timer), the RTCC will only function as an internal timer clocked internally and will ignore any external events.

RTCC is a Read/Modify/Write register, just like the IO ports. Eberhard Haug says:

... and don\'t use any TEST RTCC to check RTCC for zero e.g., because TEST will reset the RTCC prescaler like any MOV to RTCC. As a result it could happen that your 4-byte counter never counts correctly. TEST RTCC is equivalent to MOV RTCC,RTCC. If you like to check RTCC just use a MOV W,RTCC etc.

See Interrupts for more on how to setup the RTCC

The SX literature says that the dual stage synchronizer is _always_ activated on RTCC. If that is so, then the RTCC may actually be counting two LESS pulses than have actually been presented on the input pin.

Interested:

See also:

• http://forums.parallax.com/forums/default.aspx?f=7&m=249607 When you modify RTCC the next several instructions don't increment RTCC. In effect, the instruction that modifies RTCC takes several RTCC counts
  - If the prescaler is 1:8 or higher, the instruction that modifes RTCC is one count.
  - If the prescaler is 1:2 or 1:4, the instruction that modifes RTCC is five counts. The next five instructions do not increment RTCC.
  - If the prescaler is 1:1, the instruction that modifies RTCC is three counts. The next 3 instructions do not increment RTCC. +

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