Post by thread:[PIC]: keypress

Hi, Has any one ever tested how long does a human key press lasts ? I thought I saw a 10ms but was not quite sure. Any help is appreciated. It would be more helpful is someone can point me to a web source about keypad intfacing to pic. Yansong {Original Message removed}

Yansong, It would suggest it may be better to write the software such that it is independent of time key is pressed. ie. act on keypress but don't respond to further key presses until original key is released. You also normally debounce the key with a small delay (30-50ms maybe). ie. If keypress detected wait 30ms if key still being pressed, act wait till key released small delay Regards David Huisman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 10:59 PM 11/23/00 -0800, Yansong wrote: >Has any one ever tested how long does a human key press lasts ? I thought I >saw a 10ms but was not quite sure. Any help is appreciated. It would be more >helpful is someone can point me to a web source about keypad intfacing to >pic. A keypress is pressed to last much longer than 10 ms. What 10 ms corresponds to is the time period after which the key has stopped bouncing. Most keys are specified to reach steady state in 5 ms, so 10 ms is safe. If you have poor quality switches, you may want to allow 20 ms to make sure. ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: spam_OUTralTakeThisOuTlcfltd.com Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causas scire" ================================================================ -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On 23 Nov 00, at 22:59, yansong gu wrote: > Hi, > > Has any one ever tested how long does a human key press lasts ? I thought I > saw a 10ms but was not quite sure. Any help is appreciated. It would be more > helpful is someone can point me to a web source about keypad intfacing to > pic. > In Jal ( http://come.to/jal): -- some pin's and variable definition pin_c3_direction = input -- one button active low pin_c2_direction = input -- second button active low var bit curent_push, next_push -- routine for tmr_0 rollover at 20 or 50 ms tmr0_rollover --main program forever loop next_push = ! pin_c3 if ( next_push ^ curent_push ) & next_push then -- after first push button is inactive until... curent_push = next_push -- do job for this push curent_push = low -- ... until this reset -- or polling button in conjunction with t0if elsif (! pin_c2) & intcon_t0if then intcon_t0if = low -- do job for this push end if end loop **************************************** Surducan Vasile email:.....vasileKILLspam@spam@l30.itim-cj.ro URL:http://www.geocities.com/vsurducan **************************************** -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

This is really helping me for my project. Thanks all for the help. Yansong -----Original Message----- From: David Huisman <david.huismanKILLspamADVMININGTECH.COM.AU> To: .....PICLISTKILLspam.....MITVMA.MIT.EDU <EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU> Date: Thursday, November 23, 2000 8:39 PM Subject: Re: [PIC]: keypress >Yansong, > >It would suggest it may be better to write the software such that it is >independent of time key is pressed. ie. act on keypress but don't respond to {Quote hidden}>further key presses until original key is released. > >You also normally debounce the key with a small delay (30-50ms maybe). > >ie. If keypress detected wait 30ms > if key still being pressed, act > wait till key released > small delay > >Regards > >David Huisman > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics