18 Nov 2003Ryan Kittredge Digital Communications Ryan Kittredge Technical Topic Report 19 November 2003

18 Nov 2003Ryan Kittredge Three common types IEEE 1284 – Parallel port LPT1 RS232 – Serial port COM1 IIC – Inter-Integrated Circuit “I squared C”

18 Nov 2003Ryan Kittredge Parallel Port LPT1 A 25 pin connector on PC commonly known as the printer port. Uses standard logic levels. –Logic 1 = 5V Logic 0 = 0V Data is in ‘parallel’ via 8 data lines. –Can be configured for input or output. There are 5 status lines that are inputs. There are 4 control lines that are outputs.

18 Nov 2003Ryan Kittredge Serial Port COM1 A 9 pin connector on PC. Uses negative logic –Logic 1 = -3V to -12V Logic 0 = 3V to 12V Requires a method to convert back to standard logic. –MAX232 chip, UART – Universal Asynchronous Receiver / Transmitter. There are 3 lines required for operation. –Transmit, Receive, and Ground.

18 Nov 2003Ryan Kittredge

18 Nov 2003Ryan Kittredge IIC – ‘I squared C’ Uses two wires to communicate serially. –SCL – Serial Clock Line –SDA – Serial Data Line Uses standard logic levels. Software could be used to manipulate the parallel port to communicate with a ‘home made’ version of IIC.

18 Nov 2003Ryan Kittredge

18 Nov 2003Ryan Kittredge Pro’s and Con’s Requires timer from HC08 Pins used on HC08 Additional Hardware Required Ease of Impleme- ntation Best Choice Parallel Port N 10 N Easiest Y Serial Port Y 2 Y Hardest N IIC N 2 N Medium Y

18 Nov 2003Ryan Kittredge Questions? Thank you