Communication Busses

• I2C
• SPI (4-wire daisy chained SPI is one of the few buses that does not require every node on the bus to have a unique address, since each device is implicitly addressed by its position along the length of the bus)
• USB
• X10
• midi
• iButton
• Fiber Optic
• Onewire
• Ethernet

The difference between a "serial bus" and a "serial interface" and a "network protocol" is blurring -- see network protocols (TCP/IP, telephone, CANbus, ethernet, etc.), serial IO (RS485, SPI, etc.).

See also:

• /techref/ti/calc/sio.htm TI calculator protocol.
• MODBUS
  • http://www.modicon.com/ Full reference to MODBUS including source code.
  • http://members.tripod.com/~mbserver/index.htm There is a free windows modbus master that might help.
  • http://www.modbus.org has lots of usefull stuff.
  • The CRC page mentions "a very compact (no-tables) CRC-16 function in C (for modbus)"
  • Microchip PIC 16F87X - 20 Modbus RTU Slav
• The VMEbus FAQ is at http://www.ee.ualberta.ca/archive/vmefaq.html or http://www.oritools.com/info
• The I2C FAQ is available from: ftp.uni.paderborn.de/elrad
• Universal Serial Bus home page: http://www.teleport.com/~USB
• ISA pinouts can be found at http://www.cistron.nl/~nctnico/index.htm
• ISA, EISA, VLB, and PCI pinouts, signal descriptions, and timing information can be found at http://www.gl.umbc.edu/~msokos1
• "AT Bus Design, IEEE P996 Compatible", by Edward Solari ISBN 0-929392-08-6
• Official standard for the EISA bus are available from BCPR services (Texas) Tel: 1-713-251-4770
• Standards for the EISA bus are available from Global Engineering Documents, Englewood, Colorado USA at phone: (800)854-7179, fax:(303)397-7935
• The PC/104 Consortium has a page at http://www.controlled.com/pc104/ Request a resource guide and spec document.
• The PCI specification may be obtained from: PCI Special Interest Group (SIG)
  P.O. Box 14070, Portland, OR 97214
  (800) 433-5177 (503) 797-4207 FAX: 234-6762
  (503) 797 4297
  http://www.pcisig.com/
• Other PCI information:
  • http://www.teleport.com/~pc2/pcisigindex.html
  • http://www.vchips.com/products/pcicores.htm
  • http://www.altera.com/html/new/pressrel.old/pr_pcipack.html
  • http://www.cypress.com/cypressprodgate/apps/ultralogic.html
  • http://www.xilinx.com/apps/pci.htm
  • ftp://fission.dt.wdc.com/pub/otherdocs/pc_systems/how_it_works
• AMCC makes a chip which provides an interface to PCI on one side and a fairly simple generic interface on the other side. AMCC is in San Diego, California. Their telephone number is (619)450-9333. The part number for the PCI interface chip is S5933.
• Ziatech, http://www.ziatech.com has the CompactPCI spec in Acrobat. CompactPCI uses the PCI timing and pinout with a eurocard format and connector.
• D Prutchi, "Hot Swapping on the PC - An Active Extender Card for the 16-bit PC-ISA bus", Circuit Cellar Ink, Issue #62, 62-71, September 1995.
• PCMCIA specs are available from http://www.pc-card.com/ (not free) The PCMCIA association lists manufacturers with links to webpages, also links to books.

Lost somewhere in the sands of time was an interesting serial protocol used on TI graphing calculators. There's plenty of good reference material on Google, but it basically worked like this:
Two bidirectional lines with pull up resistors. The sender starts by pulling one line low, the receive end acknowledges by pulling the other line low. They both release and start again. Zero's and ones were signified by which line the sender pulled low. Works _very_ well in a busy processor since every bit waits for an ack. Data rate could be quite high with the addition of interrupts if so inclined. Opto isolation may be more challenging, but seems workable.

TI calculator protocol.