Editing BoostC from the Fourm

http://forum.sourceboost.com/index.php?showtopic=3909&pid=14605&mode=threaded&start=#entry14605


Sounds like the classic read modify write issue, when ports externally are being dragged down by whatever is connected to them. Remember that when a port is read on a PIC16 the actually logic level on the pins are read, not the last data written. This is not a problem on PIC18 if you use the LAT register as this actually holds the last data written. 

Possible solutions:
1) Don't drag down the outputs with excessive load.
2) Use a shadow register to hold the data written to the port.