Hej Jan Erik Bertram. Tack fšr ditt meddelande 15:37 991219  enligt nedan:
>There could be exists a other problem, too with the RETFIE command, because
>of the setting of GIE bit, perhaps this is also a
>read-modify-write operation.

I«m pretty sure the RETFIE command sets the GIE bit by means of a direct hardware "Set" signal to the bit, no other bits affected, (easiest to implement it that way) so RETFIE should be completely safe.


However if our *code* disables / enables global interrupt by using BSF/BCF on GIE, (or any instruction that writes to the register, really) then the problem in previous letter applies to the interrupt flags that are in the same register as GIE: T0IF, INTF, RBIF.

But again: 

1) T0 do have an synchronizing buffer according to doc.

2) RBIF is level activated, not edge, so is OK as long as mismatch >1 machine cycle (i believe)

3) INT pin is to badly documented to tell if OK.


/Morgan