----- Original Message ----- From: "Robert Rolf" To: Sent: Tuesday, September 02, 2003 5:21 PM Subject: Re: 7404 in an 8 pin DIP? > Why not use a couple of transistors for the level translation/inversion? Could I do it with a couple 2n2222s, no resistors ( I am not very good with analog electronics)? > > Or just drive the PIC pins directly with series R (1k on Rx, 100R on Tx) > and invert the logic if you're bit banging? > It is a PIC isn't it ? If it isn't, you're going to need clamp diodes > to VCC and Gnd for the Rx line. > > And if you are going to use a SMT logic device, I recommend the 74HC14 > (Schmidt). > I use it all the time in our lab on 50' cables at 19.2kbaud without problems. > The official Rx spec for RS232 says anything about 3V is a Mark and lower than > -3V is a space, and -3 to 3 is undefined (so 0V is ok). In other words, you get > a minimum of 2V of noise margin using a 74HC14 driving a 'normal' RS232 > chip like the 1489. > > John Pearson wrote: > > > > Is a 7404 or equivalent available in an 8 pin dip? Or perhaps is there a way to mount a SMD 7404 onto an 8 pin DIP adaptor, or a SIP adaptor? > > > > What I want to do is to try to use an rs232 serial connection with a 5Volt mpu using a very short cable and low speed (9600 max). > > Thanks > > -- > 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#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body