----- Original Message ----- From: "embedded engineer" To: Sent: Wednesday, May 09, 2001 5:13 PM Subject: Re: [EE]: adding an external counter > You bring up some good points. We already have RB0 connected in > parallel with USART RX for wakeup. I guess they could be or-ed or use > RB-change. A bigger problem though is reading T1. On the flash PIC > 16F873 it cannot be done as it can modify the contents of T1 itself. > That would corrupt the real time clock. See the errata for 16F873 for > example. Would this work around the T1 problem: Directly read (using BTF instructions) the port pin used to clock the T1 timer, watching for the appropriate edge to go by (either 0->1 or 1->0, whichever applies), then read T1 immediately thereafter. To get the count. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.