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]

Shorter link shouldn't require C&amp;P -&gt;
http://members.optushome.com.au/adambradley/electronics/LC/cnv.jpg

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bcb2f$0$28121$afc38c87@news.optusnet.com.au...

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

 

[Adam Bradley]

I've uploaded a couple of images of my schematic in which a TTL high and low
(5v and GND) is injected into the circuit.

Once again the two files are in
http://groups.yahoo.com/group/opendiag/files/AJB/

and called

5V connected to TTL Tx.jpg
5V disconnected from TTL Tx.jpg

The multimeter reading is taken from the K line.

Any ideas how this works?


Adam

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bccd7$0$28122$afc38c87@news.optusnet.com.au...

Shorter link shouldn't require C&amp;P -
http://members.optushome.com.au/adambradley/electronics/LC/cnv.jpg

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bcb2f$0$28121$afc38c87@news.optusnet.com.au...
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

 

[Ken Taylor]

The groups link requires a login/password, and the other links previously
used don't work ("404").

Ken

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f95b1bb$0$4845$afc38c87@news.optusnet.com.au...

I've uploaded a couple of images of my schematic in which a TTL high and
low
(5v and GND) is injected into the circuit.

Once again the two files are in
http://groups.yahoo.com/group/opendiag/files/AJB/

and called

5V connected to TTL Tx.jpg
5V disconnected from TTL Tx.jpg

The multimeter reading is taken from the K line.

Any ideas how this works?


Adam

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bccd7$0$28122$afc38c87@news.optusnet.com.au...
Shorter link shouldn't require C&amp;P -
http://members.optushome.com.au/adambradley/electronics/LC/cnv.jpg

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bcb2f$0$28121$afc38c87@news.optusnet.com.au...
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

 

[Adam Bradley]

That'll teach me for trying to clean up my home page!
Try http://members.optushome.com.au/adambradley/electronics/LevelConverter/
Adam

"Ken Taylor" &lt;ken123@xtra.co.nz&gt; wrote in message news:&lt;SFjlb.186223$JA5.4641327@news.xtra.co.nz&gt;...

The groups link requires a login/password, and the other links previously
used don't work ("404").

Ken

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f95b1bb$0$4845$afc38c87@news.optusnet.com.au...
I've uploaded a couple of images of my schematic in which a TTL high and
low
(5v and GND) is injected into the circuit.

Once again the two files are in
http://groups.yahoo.com/group/opendiag/files/AJB/

and called

5V connected to TTL Tx.jpg
5V disconnected from TTL Tx.jpg

The multimeter reading is taken from the K line.

Any ideas how this works?


Adam

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bccd7$0$28122$afc38c87@news.optusnet.com.au...
Shorter link shouldn't require C&amp;P -
http://members.optushome.com.au/adambradley/electronics/LC/cnv.jpg

"Adam Bradley" &lt;adam_j_bradley@yahoo.com&gt; wrote in message
news:3f8bcb2f$0$28121$afc38c87@news.optusnet.com.au...
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

 

[Adam Bradley]

This may be better still!
Adam

http://members.optushome.com.au/adambradley/electronics/LevelConverter/V10/

 

[Ken Taylor]

"Adam Bradley" &lt;abradley@novell.com&gt; wrote in message
news:aa9c07b7.0310220237.7ada7890@posting.google.com...

This may be better still!
Adam


http://members.optushome.com.au/adambradley/electronics/LevelConverter/V10/

Yep, can see it now.

Hmm, the read (from car to TTL) is a bit rude but it would appear to work.
No idea if it conforms to the ECU's standards though, that's your worry.

Cheers.

Ken