VN ALDL Cable

[bldnut]

many moons ago i had this set up in my vp with a carputer using db9 port, just had a rumage through some of my old files and i think this is the ads i used in the end but at the start i used a usa file that ran at 160 and modified it a bit to work with the 808, 160 is painfully slow you can red line the engine from idle and back down to idel before the the screen shows any thing

edit: just had a look around on here and I think the attached file may have come from here so it may not be the 1 I used as I had the car way back in 2005 - 2009, from memory the set up I used worked on tunerpro 3 or 4

[delcowizzid]

160 baud isnt too bad back in the day its how i tuned my whole VE table via blm and narrowband O2 sensor readings for WOT.

[bldnut]

I was lucky and had access to a dyno and wide band to tune mine

[Tazzi]

Well, that didnt work.
Hooked it up, opened up the commport and tired to read any info being set to the arduino/ftdi device but got nothing from either. Either the setup just doesnt work or the ecu isnt kicking into aldl mode with the 10k resistor.

So, I know that on my VY, I can attach the cars ground and comms line straight to the arduino and it seems to work fine (with a couple diodes and a 1k resistor).
From what I can tell, the main differences of the VNs comms is that it is at 160 baud and at 12Volts. (Let me know if Im missing something else)

With that said, shouldnt I be able to simply hook up a 1k ohm resistor to the VNs comms line to the Rx pin or arduino, attach the ground and add in the 10k ohm resistor to select ALDL mode. See image below for a sketchy schematic of what I mean!

Only concern is I dont want to fry my arduino or ftdi device in the process!. Im assuming that the application of the 1K ohm on the comms will pull the 12v down below 5v, and the ftdi device/Arduino should do the rest as previous done on my VY and let me simply open up a comport and feed any info through.

Any comments on whether this will work? Is 1K ohm enough? or should I go to 1.5 or 2?

[antus]

How are you implementing 160 baud?

[Tazzi]

I assumed I could configure the comport to 2400 or 4800 then.. just open up the port and hope for the best? lol
Didnt think anything else would of been required to start getting data through?

[VL400]

One good thing about 160 baud is its slow enough to see the data The CEL will flicker once you have the 10K resistor installed so can confirm that easy enough.

With the interface you need to make sure the polarity of the data is correct. RS232 needs to be inverted, while TTL has no inversion. The NPN circuit wont work in your setup going to the arduino or FTDI.

It might be worth using a series 1K and then a 5V1 zener to clamp it. Using just a 10K resistor should be ok providing the FTDI has internal diodes to gnd and VCC, but better off not stressing them and use the zener if you have one.

[Tazzi]

One good thing about 160 baud is its slow enough to see the data The CEL will flicker once you have the 10K resistor installed so can confirm that easy enough.

Alright, we got that happening when we tried. Least somethings working

With the interface you need to make sure the polarity of the data is correct. RS232 needs to be inverted, while TTL has no inversion. The NPN circuit wont work in your setup going to the arduino or FTDI.
It might be worth using a series 1K and then a 5V1 zener to clamp it. Using just a 10K resistor should be ok providing the FTDI has internal diodes to gnd and VCC, but better off not stressing them and use the zener if you have one.

Ah, that kinda confused me there. Do you mean If using RS232 I would need to invert the signal using a transistor, whereas if Im just directly hooking up to the arduino (TTL) that I dont need the inversion? (plus resistors and diodes)

I kept reading about the signal inverting although I was a bit lost to whether I actually needed it or if it was simply a requirement for converting to a signal to RS232 format.

[VL400]

Yeah with RS232 a '1' is low, and a '0' high. Input to an arduino/FTDI and the 160baud ALDL is opposite, with a more logical '1' being high and '0' low.

So if you want a 160baud interface to connect via RS232 to a PC you would use a NPN to invert the signal.
Connecting to a FTDI or direct to an arduino wont need to invert the signal, just clamp it to your VCC voltage.

[Tazzi]

Ok, thats cool. Cheers VL, It is more logical being 1=high and 0=low.

Ill give a go with the ftdi device first when I next see my mate. If thats a go, will look at using the arduino and put the sd card shield to use for a long trip log.
Might be a silly question, but is it safe to drive the car round while in ALDL Mode?