In my understanding, BODEN will hold the chip in reset if Vcc is= too low. Its thresholds are set unconditionally to be compatible= with 5v, so if you attempt to run at 3.3, BODEN will always hold= the chip in reset. It would have been more useful to have a BODEN_3.3 and BODEN_5.0,= or maybe a BODEN with an adjustable threshold, but Microchip did= not do it that way. Can someone else back me up on clearing BODEN for 3.3v designs? I= may be out on a limb here. --- Original Message --- >From: "Leo Dep" >To: =A0 >Sent: Wed, 29 May 2002 16:06:07 +0200 >Subject: Re: [PIC]:Powering the 16F877 with a 3.5 V, no quartz= oscillate. > >Hi Brent > >many thanks for your interest and suggestion, I have read the= documentation >about the BODEN, but sincerely I do not have understand its= meaning. >If the actual circuit work with 5 Volt, why I need to change the= BODEN when >I work with a low voltage? > >Best regards > >----- Original Message ----- >From: "Brent A. Crosby" >To: >Sent: Wednesday, May 29, 2002 4:17 PM >Subject: Re: [PIC]:Powering the 16F877 with a 3.5 V, no quartz= oscillate. > >Did you turn BODEN off? > >--- Original Message --- >>From: "Leo Dep" >>To: >>Sent: Wed, 29 May 2002 14:47:11 +0200 >>Subject: Re: [PIC]:Powering the 16F877 with a 3.5 V, no quartz= oscillate. >> >>Hi PIClist friend, >> >>I have a working 16F877 powered with a 5VDC, with a 20 Mhz= quartz. >> >>Powering the same circuit with a 3.5 VDC, the PIC refuse to= start. >> >>Looking with a scope on pin 14, the quartz of 20 Mhz, it= oscillate with an >>amplitude betveen the 0,8 and 1,9 Volt, and on pin 13 a fixed= level of 1,2 >>Volt. >> >>If I change the quartz with one of 8 Mhz, I obtain a bigger= oscillation >>signal, mat not suficient to start the PIC. >> >>I have some spare 74HC14 available, it can be useful? >> >>Regards >> >>Leo > >-- >http://www.piclist.com hint: The PICList is archived three= different >ways. =A0See http://www.piclist.com/#archives for details. > >-- >http://www.piclist.com hint: The PICList is archived three= different >ways. =A0See 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.