BR16F84-1.07 ETC, BR16F84-1.07 Datasheet - Page 11

• Manufacturer Part Number: BR16F84-1.07
• Description: OBD II Interface Chip
• Manufacturer: ETC

All other pins are not used. Normally, you do not need a shield,
so if present, the shield need not be connected.
It is recomended to keep the cable length 30 Ft or less,
but you may be able to make it longer, depending on the characteristics
of the cable and the serial port itself.
-------------- NOTES ON COMPONENTS ------------------------
Most of the resistors can be standard 5% carbon film.
There is one resistor (270 Ohms) which should be 1/2 watt.
If you only want to use this circuit with one or two types of protocols,
you can look at the schematic and omit any parts that are not needed.
For example, if you only wanted to use with VPW (Domestic General Motors),
you would only need 3 wires (pins 16,5 and 2) connected at the vehicle.
In this case, you could also omit several components from your circuit.
Here are some examples of parts that can be omitted.
If you don't use PWM, you can omit:
R4, R6, R7, R8, R9, R10, Q1, Q2, D1
If you don't use ISO, you can omit:
R15, R16, R17, R18, R19, R21, Q4, Q5
If you don't use VPW, you can omit:
R13, R14, R23, R24, D2, D3, Q3
The components used in the schematic are not critical.
Except for the pre programmed microcontroller and the crystal,
you can probably get all the parts from Radio Shack,
(They are usually available for less cost at electronics stores
or by mail order.)
You can use plain 5% tolerance carbon film resistors.
If you build this circuit on a piece of perfboard or a pc board
without an enclosure:
Take care that you don't lay it on a conducting surface,
causing it to short out. Your vehicle is pretty well protected,
but you could damage the interface circuit or keep it from operating.
Note that there is no reset button for the interface processor.
To reset just unplug from vehicle, then replug it to the vehicle.
(That will automatically reset the interface processor).
Then restart the PC's software program and reinitialize the interface.