This is a free technology guide. It is written in human language and
instructs user to build I2C2P device himself with as little thinking as
possible.
Input
- Ability to perform actions exactly as written and send bugreport
in case the guide is ambiguous
- Place where manual soldering is possible
- Ability to work with tiny (SMD) parts.
- Access to a PCB manufacturer
- Material: see component lists
Output
One or more populated working PCB's without casing. Casing is
unfortunately not yet resolved :(
Specification
- Parallel port connector: DB25 male mounted on I2C2P PCB, with hexagonal
nuts. It's necessary to unmount nuts from PC or replace nuts on parallel port
cable with screws.
- Parallel Port Pinout:
| Function | Direction | Parallel port name | Parallel port pin
| Polarity *)
|
| SDA | Parport -> I2C | /STROBE | 1 | noninverted
|
| Parport <- I2C | BUSY | 11 | noninverted
|
| SCLK | Parport -> I2C | SLCT | 13 | noninverted
|
| Parport <- I2C | /ACK | 10 | noninverted
|
| Power | Parport -> I2C | D0 | 2 | all H = power on
all L + /STROBE L + SLCT L = power off
Other=function undefined
|
| Parport -> I2C | D1 | 3
|
| Parport -> I2C | D2 | 4
|
| Parport -> I2C | D3 | 5
|
| Parport -> I2C | D4 | 6
|
| Parport -> I2C | D5 | 7
|
| Parport -> I2C | D6 | 8
|
| Parport -> I2C | D7 | 9
|
| Parport -> I2C | /AUTOFD | 14
|
| Parport -> I2C | /INIT | 16
|
| *) Path between parallel port connector and I2C connector is meant.
|
- I2C connector: RJ12 female monted on PCB.
- I2C connector pinout. It has 6 pin slots from which only
contacts 2-5 are present:
| Pin number | Function
|
| 1 | Contact not present
|
| 2 | +5V
|
| 3 | SDA
|
| 4 | SCL
|
| 4 | Ground
|
| 6 | Contact not present
|
- Dynamical properties:
- Delay: in both direction on both lines approximately 500ns
- Adapter is ready for operation after 100ms from
power on
- When the device is not plugged into parallel port (i. e. powered off) or
the computer is turned off or power is
turned off, the I2C bus is guaranteed to not be loaded.
- I2C2P must work on all IEEE1284 ports. From measurements
of three different parallel ports and careful design of I2C2P it seems that
it will likely work on all previous ports. But it cannot be guaranteed due to
unspecified nature of these ports.
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Send feedback to 
| (c)1998-2004 Karel 'Clock' Kulhavý |
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