Post by thread:[PIC]: Serial bit banging with 32 kHz Xtal?

Hello: Can serial coms work, even at a slow speed, by bit banging when the crystal is 32 kHz? Thanks, Brooke Clarke -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Yes, it does work. But how slow do you want it to be? Tan C C -----Original Message----- From: pic microcontroller discussion list [spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU] On Behalf Of Brooke Clarke Sent: Saturday, September 07, 2002 1:39 AM To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU Subject: [PIC]: Serial bit banging with 32 kHz Xtal? Hello: Can serial coms work, even at a slow speed, by bit banging when the crystal is 32 kHz? Thanks, Brooke Clarke -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Can serial coms work, even at a slow speed, by bit banging when the crystal is > 32 kHz? Yes, but only at a very slow speed, <= 600 baud perhaps. - Michael -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Sat, 7 Sep 2002 01:54:39 +0800, you wrote: >Yes, it does work. But how slow do you want it to be? ..and how much CPU time do you need for other tasks.... I guess 1200 would be possible, _perhaps_ 2400 if you don't need any CPU bandwidth for anything else. This would be based on getting an int off the startbit, then staying in the int code for the whole byte. I've done 115Kbaud rx at 4MHz like this. >Tan C C > >{Original Message removed}

> Can serial coms work, even at a slow speed, by bit banging when the crystal is > 32 kHz? Sure, as long as the bit rate is slow enough. You should be able to do 300 baud. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Fri, 6 Sep 2002, Brooke Clarke wrote: >Hello: > >Can serial coms work, even at a slow speed, by bit banging when the crystal is >32 kHz? Yes, I've done it. Try 600 or 1200 Bauds. There will be a small timing error that is up to the max allowable timing error you are permitted in serial comms. I did my own RTC chip, with a twist or two. You cannot receive at these speeds, but I think that 150 or 300 Bauds can be received too (haven't tried). I used pushbutton style set and shift adjust buttons, wired to real buttons or to another mcu. Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

I don't have tested, but in "cheapic" http://www.piclist.org/techref/piclist/cheapic/index.htm ) tehere is the code (ALPHABET.ASM , 16F84 based) for 1200 baud with 32Khz crystal. Marco {Original Message removed}