Hi, The answer depends on how you are going to use it. I would recommend using synchronous mode with one the master, the other the slave. Read the chapter in the data sheet on the usart, then re-read it. There are a lot of features that can make your life easier doing this. Assuming you go this route: 1. - Configure TRISB<2:1> as 1's (inputs) 2. - Connect the data line's together, and connect the clock lines together. The bus is bi-directional, with the master supplying the clock. 3. - How fast to remove data from the RCREG depends on your clock rate, and the baud rate used by the master. You should have "plenty of time" to get the data out and into a buffer in an ISR. Don't do too much processing in the ISR though. For two PIC's, I would have the master send a data packet (can be more than one byte), then wait for awhile for the slave PIC to respond, then turn on the RX in the master. The slave should be set for continuous receive, and be ready to get the rx data out fast (ISR recommended). The other way is to have the master send his data, then go into slave mode until he gets a response (put a timeout on this). The slave gets the data, processes it, when ready to respond, switches to slave mode and sends. After sending the slave returns to slave mode. Remember that slave/master mode determines who sends the clock. The system I am working on uses another line as a chip select. The slave only listens when his CS is set low. He then waits to transmit (if he has data) until his CS goes low again. The PIC also has address detection built in if you ever need more than one slave PIC. I have a 16F628 reading data in the slave mode and data comes in at over 4Mbs. There are gaps in the data so I can still do other things, but during comms, the code must be tight. BTW I am running the PIC at 20MHz. Hope this helps Norm - NC7I -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Mias Van Vuuren Sent: Wednesday, July 11, 2001 6:57 AM To: PICLIST@MITVMA.MIT.EDU Subject: [PIC] : USART on 16F628 Hello everybody I am trying to get the usart running between two 16F628's, and need some help. 1. how do I configure portb<2:1> i.e. as inputs or outputs. 2. How do I connect the two pics, i.e. portb1 to portb2 and vice versa, or portb1 to portb1, and portb2 to portb2. 3. if I enable continuous reception, how fast do I have to move the received info from the rcreg to somewhere else, and does that mean I need to send a byte at the transmitter, then wait a while and send another? Thanks. Mias van Vuuren e-mail : vanvuum@vodacom.co.za -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics