Hi Mike, Sorry about the CC (are you getting two of this message, if so please let me know and I will stop CCing you). Yes, I am using an old version of OrCAD (v4.???). I'm very new to the PIC, but I have a 16C84-04 and a 16F84-10 to play with. This PIC list is great -- I found out a lot from all the email bouncing around (but I still have a LOT to learn). I would appreciate any hints, circuits, starting points, etc. I want to connect a 2x16 line LCD (8 data lines + 3 control lines), a fully addressed ISD voice chip (10 address lines + 3 control lines + 2 status lines), compass module (1 data line + 4 control lines), serial communication (PIC to PIC: 1 data line + gnd). 3 or 4 push buttons, Hex rotary switch - BCD format (4 lines) and 2 or 3 misc I/O (2 or 3 lines?). Also maybe some motor control lines and a data line for hall effect sensor (to keep track of motor). If there is enough I/O, then maybe control the LCD contrast with digital pot (4 lines?). Digital volume control would be nice too (4 control lines - using a digital pot???). Does the PIC need to read data FROM the LCD. I know that bit 7 needs to be read for the LCD busy flag, but do the rest of the lines need to be accessed??? I wish to do a few custom graphic characters in the LCD (an Up and Down arrow.....funny that they don't have these, as there is a left and right arrow in the character set). I think that I am allowed to create up to 8 custom characters???? More questions: A) I wish to use: 1) The internal watchdog 2) The timer for PIC to PIC serial communication 3) The timer for frequency measurement (20KHz to 80KHz) Can I do this? I was thinking that if I can't, then maybe using an external watchdog & power sense chip (Dallas DS1232). B) How can I isolate the lines to implement in-circuit-programming (ICP)? I wish to use have access to the MCRL line for reset from external watchdog & power sense chip and also a pushbutton manual reset. How can I isolate the B lines (PB6 & PB7 used for programming)? I was think of using an HC245 and disabling the chip (Z state) when using ICP but then I would need to enable the chip when using it for the real circuit. I can use a PNP transistor to isolate the PIC and HC245 chip power so that they are the only ones powered up during ICP. Comments???? .....please! Thanks -Randie /*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/ */ Randie Ohtsji /* /* Glenayre R&D, Vancouver, BC CANADA Phone: (604) 293-1611 x4555 */ */ Email: rohtsji@glenayre.com Fax: (604) 293-4317 /* /*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/ > From msmith@pasteur.dialix.com.au Fri Oct 17 05:12:25 1997 > From: "Mike Smith" > To: "Randie Ohtsji [4555]" > Subject: Re: What is the best way to sense a pushbutton press??? > Date: Fri, 17 Oct 1997 21:36:10 +0930 > MIME-Version: 1.0 > Content-Transfer-Encoding: 7bit > X-Priority: 3 > X-MSMail-Priority: Normal > X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 > > > -----Original Message----- > From: Randie Ohtsji [4555] > To: PICLIST@MITVMA.MIT.EDU > Cc: msmith@PASTEUR.DIALIX.COM.AU > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > Hmm, you didn't wan't me to miss your reply > > > > > Date: Friday, 17 October 1997 2:00 > Subject: Re: What is the best way to sense a pushbutton press??? > > > >Mike, > > > >Thanks for the response! > > > >The B lines (PB0 - PB7) are used as both inputs and outputs (with HC373 > >and HC244 chips) so I can't dedicate them to trigger an interrupt from > >a switch. > > You could, actually. Do you have a schematic design editor? If so tell me > which format, and I'll send you some ideas - I wont guarantee functionality, > just to serve as starting point. Which PIC you using? > > There will be about 4x HC373 and 2x HC244 used (chip selected > >by the HC138) so the B lines sequence will go something like: Output1, > >Output2, Input1, Output3, Output4, Input2. The switch will be on Input2. > >......err I hope you are getting what I am trying to say. > > Most Pic'sters try to maximise this stuff inside the PIC to minimise cost. > Maybe give me an idea of switch count and output device latched pin count. > Is o/p a display? > > > > >Since the B lines will only look at Input2 (the switch input) a minimum > >of 1/6 of the time, I need to capture the switch press by using the > >Flip-flop. > > > >Is the circuit and logic of what I am attempting to do the best way to > >capture a switch press???? > > Maybe. > > > >I thought the Flip-Flop could be used for de-bounce. > > > > Yes - but less flexible - for instance if you want a held down switch > condition, its easier in s/w > > MikeS > > >