Post by thread:Beginner In Need Of Help

Hello Everybody, Well, thanks to the RTF from Tim Hamel (http://pc-tek.hypermart.net/begin.rtf) I am well on my way with learning about PIC programming. I am having one hitch though. Could anyone say how the heck I access ports A and B? I am not entirely clear on how and when to use the STATUS register to enable port access. Is the access method for output the same as for input? Help. Thanks much. Regards, Ricardo F. Chung Kingston, Jamaica

In a message dated 1/9/00 10:04:09 PM Pacific Standard Time, spam_OUTrfchungTakeThisOuTANNGEL.COM.JM writes: > Hello Everybody, > > Well, thanks to the RTF from Tim Hamel Anytime =) > (http://pc-tek.hypermart.net/begin.rtf) I am well on my way with learning > about PIC programming. I am having one hitch though. > > Could anyone say how the heck I access ports A and B? I am not entirely > clear on how and when to use the STATUS register to enable port access. Port A and Port B are seperate memory addresses. Port A is at address 0x05 and Port B is at 0x06. In Port A's contents (I assume you're talking about the 16F84), only 5 bits are used, 0 to 4. With Port B, all 8 bits are used. Now, the STATUS register is for bank selecting, status bits, etc. Usually you use bit 5 of the STATUS register to switch to Bank 1 where from there you set the ports' state. Even though Microchip hates us for doing it, it's easier to just use the TRIS instruction to set the pin states. > > Is the access method for output the same as for input? Help. Thanks much. Yes > > Regards, > Ricardo F. Chung > Kingston, Jamaica > Hope this helps, Tim Hamel

<x-flowed>Ricardo F. Chung wrote: >Hello Everybody, > >Well, thanks to the RTF from Tim Hamel >(http://pc-tek.hypermart.net/begin.rtf) I am well on my way with learning >about PIC programming. I am having one hitch though. > >Could anyone say how the heck I access ports A and B? I am not entirely >clear on how and when to use the STATUS register to enable port access. > >Is the access method for output the same as for input? Help. Thanks much. The STATUS register is not required for port access. Treat the port just like any other register - use MOVF & MOVWF for I/O. You must however set the port up first by setting the respective TRIS registers. The Microchip data sheets & examples should give you the idea. Regards... ___________________________________ David Duffy Audio Visual Devices Ph: +61 7 38210362 Fax +61 7 38210281 .....AVDKILLspam@spam@uq.net.au Unit 8, 9-11 Trade Street Cleveland, Qld, 4163, Australia. ___________________________________ </x-flowed>