Q: 5V<->12V level conversion

[Adam Bradley]

I'm after some validation of this circuit -&gt;
http://members.optushome.com.au/adambradley/electronics/LevelConverter/cnv.j
pg

I'm after a way of sending/receiving from my car ECU a 12V digital signal
using a uController (AVR).

A kind sole presented the above circuit. Based on the labelling, to transmit
from the car (12V) to uController(5V), place 12V (or 0V) on the collector of
Q1 (labelled K line) and read on Tx.

To transmit from the uController, place 5V (or 0V) on Rx and read
from the K line.

I've also discovered placing 5V (or 0V) on the emitter of Q1
(labelled Tx) works! This freaks me out! Why does this work ?

Anyone got any general suggesions as to whether this is a good
approach. Also, if I want to include optoisolate this circuit (in
both directions) how would I go about doing this given a single line carries
Tx and Rx information?

Thanks in advance!

Adam

 

[Adam Bradley]

I have what I think is a cicuit that will work at
http://members.optushome.com.au/adambradley/electronics/LevelConverter/V10/

Any comments?
TIA!
Adam

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message news:&lt;3f8bf2a8$0$4845$afc38c87@news.optusnet.com.au&gt;...

I'm after some validation of this circuit -
http://members.optushome.com.au/adambradley/electronics/LevelConverter/cnv.j
pg

I'm after a way of sending/receiving from my car ECU a 12V digital signal
using a uController (AVR).

A kind sole presented the above circuit. Based on the labelling, to transmit
from the car (12V) to uController(5V), place 12V (or 0V) on the collector of
Q1 (labelled K line) and read on Tx.

To transmit from the uController, place 5V (or 0V) on Rx and read
from the K line.

I've also discovered placing 5V (or 0V) on the emitter of Q1
(labelled Tx) works! This freaks me out! Why does this work ?

Anyone got any general suggesions as to whether this is a good
approach. Also, if I want to include optoisolate this circuit (in
both directions) how would I go about doing this given a single line carries
Tx and Rx information?

Thanks in advance!

Adam

 

[Anantha Narayan]

some interfacing circuits may help you
http://delabs.tripod.com/cirdir/micro1.html
you may get the solution at my web pages
over 100 circuits
all are useful,
http://delabs.tripod.com/