Post by thread:[PIC]: PIC to PIC Interfacing?

Dear PicSters,

as a newbie i have chosen the 16f84 to start myself off. i was wondering how i can connect two of them together, or maybe even three, so that i could have one main pic, and use another/others to control separate things like motor control hardware eg.servos, and sensors! and use another to control i/o devices like rs232 computer interfaces, lcds, and rf transcievers.

Thankyou all for your time

Anamalech

Web: www.anamalech.multiservers.com

Email: anamalech@hotmail.com

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I have done something like that. Reads servo commands from an RC receiver, calculates and generates servo commands to output, controls motors, and updates an LCD. I put each pic on a separate board, all plugged into a backplane for power and the communication bus. The bus consisted of 8 data lines, ground, power, and a couple of control lines. I used FRAM for the shared memory because I couldnt find a small serial RAM. The project is explained at http://www.technogap.com/computer.htm {Original Message removed}

The 16F627 or 16F628 is a better choice over the F84. It has a built-in UART that can be used to address other PICs by "name", as it can transmit codes that will start other F628s working. It will also be easier for you to interface to the RS232 of a PC You can still use I2C or your own custom bit-banging if you want to stick with the F84 (or indeed use it with the F628). Take a look at how I2C systems work and emulate it with PICs. One advantage you have with the micros is that they are smarter than I2C chips like memories, and it would be possible to have full duplex I2C. That is, one portion of the PIC can be a listening slave, another portion can be a transmitting master. It's something that would be good to set out on paper and do a logic flow. With processor speeds of 20MHz, I2C at 400kHz means a lot of room to manouevre -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

A couple of suggestions: 1) Please don't post HTML to the list. Not everyone uses a web based E-mail reader to read mail. 2) Especially for what you are doing you may not want to use the 16F84. The simplest way to handle communcation is to use hardware peripherals, like a USART, or I2C interface. The 16F84 doesn't have these. However Microchips newer flash parts, for example the 16F628 or the 16F672, do. And Microchip has them priced cheaper than the 16F84, at least in the US. Take a look at using the USART in 9 bit mode with EIA485 (RS485) for addressible, multidrop communication. But you'll spend a lot for time and effort doing this with a 16F84. BAJ -- 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

> 2) Especially for what you are doing you may not want to use the 16F84. The > simplest way to handle communcation is to use hardware peripherals, like > a USART, or I2C interface. Personal favorite of mine is the Parallel Slave port on the '877 and others. -- Jon Baker -- 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

Jon, Do you have more information about I2C (PIC to PIC communication) that you you give me? Thanks Aryldo G Russo Jr Research and Development Manager AeS Automação e Sistemas Ltda. Address: Rua Domingos Barbieri, 294/298 ZIP: 05531-060 - City/State: São Paulo/SP Tel.: + 55 11 3722-1166 + 55 11 3721-5333 Fax.: + 55 11 3721-0567 -----Mensagem original----- De: pic microcontroller discussion list [spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU] Em nome de Jon Baker Enviada em: sexta-feira, 18 de janeiro de 2002 12:43 Para: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU Assunto: Re: [PIC]: PIC to PIC Interfacing? > 2) Especially for what you are doing you may not want to use the > 16F84. The > simplest way to handle communcation is to use hardware peripherals, > like a USART, or I2C interface. Personal favorite of mine is the Parallel Slave port on the '877 and others. -- Jon Baker -- 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 -- 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

> Do you have more information about I2C (PIC to PIC communication) > that you you give me? http://www.piclist.com/techref/microchip/i2c.htm Philips I2C "how to" http://www.semiconductors.com/acrobat/various/I2CBUS.pdf -- 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

> Do you have more information about I2C (PIC to PIC communication) > that you you give me? I should add this one http://www.semiconductors.com/products/all_other.html Further I2C references, and more. One thing the Philips site isn't short of is data sheets, if only some other manufacturers were so forthcoming -- 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