Aldl interface, 2 transistor type

[tucson kid]

I have 2 transistor aldl interface that works with older 160 baud ecm 747, the question is will it with Tunerpro rev 5, and a ecm with 8192 baud if connect to Pin M. i am thinking upgrading to faster ecm

[1320_john]

Do you have the schematic? Most of the designs should work. One transistor would pull the serial data line low. The other transistor was used to buffer the receive line IIRC.

[f85gtron]

Have you read this thread on the max232 chip? http://www.gearhead-efi.com/Fuel-Injection/showthread.php?719-Uber-easy-DIY-USB-ALDL-Cable&highlight=Max232
I originally made a two transistor cable, but couldn't get it to work. This chip works perfect and it's fast. Oh, and it's cheap too!
I just use paperclips to interface with the aldl port.

[tucson kid]

I have tried a couple of times to put one together, but have not got them to work with my 747 ecm. Not sure what issues is, there is two different circuits that have seen. What ecm do you have that worked with maxx232 chip, did you buy it already put together? I really thank you for replying

[lionelhutz]

You could use a USB to TTL serial converter. About $5 shipped from China or $10-$15 from US sources. I can dig up the thread if you're interested to see the part and how to connect.

[tucson kid]

yeah I might want to try it, thx

[lionelhutz]

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4586-Building-16pin-ALDL-USB-cable-(94-95-Camaro)

Use a 1N914 diode and a 1k resistor. I have only tried the JY-MCU boards and they worked for me, but any FT232RL chip based board should work.

The only thing to note is that apparently there are some counterfeit FT232RL chips around that don't work with the official FTDI drivers. The JY-MCU ebay listing did state it was an original FT232RL chip.

[f85gtron]

I have tried a couple of times to put one together, but have not got them to work with my 747 ecm. Not sure what issues is, there is two different circuits that have seen. What ecm do you have that worked with maxx232 chip, did you buy it already put together? I really thank you for replying

I've used that max232 ttl board with both 160 (various fiero ecms) and 8192 baud (7730) ecms. Also used it with tuner pro and aldldroid.
The chip comes mounted in a breakout board and all you have to do it push the supplied breakout wires onto the correct pins and away you go.
My two transistor board that i ruined started out as a one transistor for 160baud, then i did an ecm swap and built a two transistor for 8192, but i never could get it to connect. I gave up and bought the chip and never looked back.

[RobertISaar]

i had the same issue with a 2-transistor setup, worked fine for 160 baud, never got it to function with an 8192.

I've done both MAX232 and USB/UART bridges, both work great in any application I've tried them in. if you go the USB route, the FT232 is the most consistent route(even if you have to use an older set of drivers if you manage to pick up a cloned chip), though the CP2012 works too, IIRC. have to modify the driver though.