Thanks Bob, That's a cool trick to use a PWM 50% oscillator on one uP to drive the clock for another. The primary PIC is actually a Rabbit and someone on their list just suggested a cool trick. I was trying to figure out if their PWM would produce the 32, 38, and 40khz 50% duty cycle carrier signals. It can't, but their async serial port can by setting the right baud rate and sending 0x55's as data. For each pulse of the carrier in the IR protocol, I would just write a number of 0x55's to the serial port. I am still considering the 8pin PIC though. I am wondering if it would have enough juice to process the raw IR signal. Most IR receivers filter for a fixed carrier freq. That's fine for an end product that's being controlled, but for a universal remote, you really want to receive all 3 carrier freqs (the popular ones, anyway) and assemble any and all proper signals. It would be cool if that one little 8pin would be able to transmit on any carrier and receive on any carrier. The comm. Protocol you mentioned could be extended to be bi-directional so the 8pin would send received signals as they arrived. I bet its too much for it, though. I seem to remember that they do not even have an external interrupt, so polling the raw IR receiver line with all the ambient noise would probably be too much for it. When I get the time, I am going to try it, though. --BobG -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Ammerman Sent: Thursday, September 12, 2002 11:21 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Infrared Communications -- Use an 8PIN PIC! ----- Original Message ----- From: "Bob Ammerman" To: Sent: Thursday, September 12, 2002 7:54 PM Subject: Re: [EE]: Infrared Communications -- Use an 8PIN PIC! > How about setting up an 8 pin PIC as follows: > > Generate the clock by connecting to a PWM output of the main PIC. PWM set up > with PR2=0, TMR2 Prescale=1:1, Duty cycle = 50%. This will result in a clock > for the 8PIN pic that is 1/4 the clock of the main PIC. Set PR2=1 to get a > clock 1/8 that of the main PIC. > > Now use data pins as follows: > > Data out - generated infrared signal send to LED driver. > Data in - data supplied by primary PIC > Clock/Ready - open drain output connected to the primary PIC and a pullup R. > You've got 3 more pins availalble for future use! Whoops,.... that would be 2 pins to spare (forgot about the clock pin) Bob Ammerman RAm Systems -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu