> -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of Olin Lathrop > Sent: 02 August 2010 13:42 > To: Microcontroller discussion list - Public. > Subject: Re: [PIC] wake from sleep using serial port on 16F77 >=20 > Michael Rigby-Jones wrote: > > I have probably missed something here, but the USART will also > > generate an interrupt when it receives a character in asynchronous > > mode. >=20 > Yes, but that requires the clock running, so can not be used to wake the > processor from sleep. Some of the newer UARTS do have a wakeup capability. >=20 Right - as I suspected I was overlooking something! Thanks. I suppose running in synchronous mode you are going to need at least 8 clock cycles to get an interrupt, worst case that could be 8 complete bytes if those bytes happened to be 0xFF. I wonder if you could switch the pin to an output and toggle it to 'manually' preload the USART with 7 bits prior to sleeping? The bus conflict problem would need to be fixed (simple resistor would probably suffice) even assuming this is possible. Mike =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .