I built my own serial port adapter based on MAX232. It works perfect with my only serial device I have at home: my ADSL router, it connects at 9600 baud.
For long time I have not been able to put it to work with Vag-Chek and my OBD-II adaptor based on 232 chip (there are some others based on optocouplers) to do car diagnostics. I know my OBD-II adaptor works fine because I tested it with a laptop and Vag-Com v311.2 application :approve:
I did tons of tries witch includes building my own optocoupler adapter, replacing MAX232 / 1uF capacitors by MAX 3232 / 0.1uF capacitors, powering MAX3232 with 3.3v versus 5v, slowing down processor speed with XCpuScalar, using older versions of Vag-Check… and all crazy combinations among all of that
It started to have some results once I slowed down processor speed. I found some information where it is said that Axim baud rate is based on processor speed and it should be set to 300MHz, is it right?
The slower speed I set the better connections I get. I get the best results when setting slowest speed available of 104MHz.
I addition to this I get better connections when using the oldest Vag-Check version 1.1.1, but still only few tests get connected to car
Is there any one that could add any comment on this? :nw: :nw:
I found some information where it is said that Axim baud rate is based on processor speed and it should be set to 300MHz, is it right?
I cannot believe this. I'm as sure as I can be, without proof, that the axim has a separate baud rate generator.
It sounds to me like your problems relate to 'hand shaking'. It seems likely that slowing the axim is merely giving the external device more time to respond.
Do you have access to an oscilloscope or other data analyser?
I cannot believe this. I'm as sure as I can be, without proof, that the axim has a separate baud rate generator
Me neither, here is the link: http://www.robsaudiworld.com/vag.htm, see paragraph "Hardware issues".
But it took me add it to my tests and once I set any fixed processor speed it starts to connect. As I slow the speed the number of connect successes increase. With 104MHz it never fails.
Originally Posted by Bill_Todd
It sounds to me like your problems relate to 'hand shaking'. It seems likely that slowing the axim is merely giving the external device more time to respond
You are probably right, Vag-Check allows me to enable/disable RTS signal (my serial circuit does have RTS) and I could see no effect.
When I say it never fails I am referring to just 4 tests, there are a lot more that never get connected, probably because data streams are longer.
Originally Posted by Bill_Todd
Do you have access to an oscilloscope or other data analyser?
Not now, probably in one week.
It seems serial port does not like too much my RS232/OBD-II adapter, but I would like to know what is happening before buying another one. My adapter woks perfect with a laptop, it is confusing me.
On the other hand my serial port woks perfect with my ADSL modem, but I think it does not use handshaking.
Me neither, here is the link: http://www.robsaudiworld.com/vag.htm, see paragraph "Hardware issues".
But it took me add it to my tests and once I set any fixed processor speed it starts to connect. As I slow the speed the number of connect successes increase. With 104MHz it never fails.
The more I think about it the more certain I am that the baud rate is uneffected by the cpu speed. So, if cpu speed effects the connection, it must be due to character and/or block timing.
Perhaps the car's system does not impliment flow control correctly (or not at all), the section:
Quote:
Under Tools there are settings for the serial connection, Char Interval and Block Interval. Alfredo (the author) states : "If you decrease these values, it should speed up your connection, but the application could become unstable. Char bit rate is the wait time between transmission of a character and next, block rate is the time wait from a packet received and its response."
suggests to me that it requires some manual adjustment to get the timing correct on a car-by-car basis.
My car uses ISO9141-2 witch needs a baud rate of 10400. I am wondering if X51V can set that baud rate, I have never seen it in terminal apps. Maybe Vag-Check is internally setting the closest standard of 9600 and that is the reason of so random behavior.
Is thre any tool to see COM1 setting when other application is connected in background?
It seem Vag-Chek is playing low level functions to get non standard 10400 baud rate. May be it is processor speed dependant.
Ah! yes, that would explain it.
I think if I were going to develop an interface, I'd use a small PIC (microcontroller) to receive at 10,400, buffer and output at, say, 19,200 to the axim (and vise-versa). The PIC can drive the LEDs in the optoisolators directly and talk to the axim in (inverted) ttl, thus avoiding the need for a level converter.
I think if I were going to develop an interface, I'd use a small PIC (microcontroller) to receive at 10,400, buffer and output at, say, 19,200 to the axim (and vise-versa). The PIC can drive the LEDs in the optoisolators directly and talk to the axim in (inverted) ttl, thus avoiding the need for a level converter.
I think it is sold already made. PDA OBD-II apps like OBDGauge only deals with with 9600 and 19200 baud in its configuration. Now I know why I have never been able to connect with OBDGauge. None of my interfaces (IC 232 or optoisolar based) are listed as valid for OBDGauge. Valid interfaces listed are all expensive, probably all of them are microcontrolled.
Well, this is the answer I was looking for. Now it seem reasonable to buy other sort of interface.
I am still wondering if I would be able to set more stable communications playing with processor speed. XCPUScale only allows me changes in broad steps,
Do you know any other application to set accurate processor speed?
I would use what Bill_Todd said and use a PIC to buffer the comms between the two systems, many PICs these days have everything built onto them (including Serial IOs and clock generators) so you can get it all working on one IC with a power supply. Many PICs also cost less than £3 and the development software is free so it is quite cheap to make, all you need is time.
If you absolutely have to have the processor at a specific speed look at Pocket Hack Master from http://www.antontomov.com/web/index.php which allows quite of possibilities for processor speeds.
I would use what Bill_Todd said and use a PIC to buffer the comms between the two systems, many PICs these days have everything built onto them (including Serial IOs and clock generators) so you can get it all working on one IC with a power supply. Many PICs also cost less than £3 and the development software is free so it is quite cheap to make, all you need is time.
If you absolutely have to have the processor at a specific speed look at Pocket Hack Master from http://www.antontomov.com/web/index.php which allows quite of possibilities for processor speeds.
Wow, what a nice front end. But it still cann not control processor speed, I will track it.
I just make some web search about microcontrollers, it seem easy and I also enjoy building circuits, but as you said I need time. My Aximizer project took all my spare time. I also searched to buy the device and I think I can get it for €30-40, not bad.
Using a microcontroller with inbuilt oscillator you should, theoretically, be able to use any serial speed you like on either side of communications, even making the speed selectable in software or hardware. The main issue is that a lot of microcontrollers require some special hardware to program them which is something I forgot about as I work in an environment where we have these tools.
There might be an issue with using this with the VAG-check software, it is setting up the serial port on the Axim to work in unusual ways so even the microcontroller may have difficulty working with vag-check, especially if vag-check attempts to use a range of baud rates (as is suggested on their site) to communicate with as wide a range of devices as possible.
I think what the people who wrote vag-check need to do is have the pocket pc running at a standard speed for the serial port and then support a microcontroller for adjusting communications speed in line with the serial cable.
Sorry to be a doom sayer, just looking at the possibilities... It should be possible, but you may have some hurdles to overcome.
Using a microcontroller with inbuilt oscillator you should, theoretically, be able to use any serial speed you like on either side of communications, even making the speed selectable in software or hardware. The main issue is that a lot of microcontrollers require some special hardware to program them which is something I forgot about as I work in an environment where we have these tools.
There might be an issue with using this with the VAG-check software, it is setting up the serial port on the Axim to work in unusual ways so even the microcontroller may have difficulty working with vag-check, especially if vag-check attempts to use a range of baud rates (as is suggested on their site) to communicate with as wide a range of devices as possible.
I think what the people who wrote vag-check need to do is have the pocket pc running at a standard speed for the serial port and then support a microcontroller for adjusting communications speed in line with the serial cable.
Sorry to be a doom sayer, just looking at the possibilities... It should be possible, but you may have some hurdles to overcome.
No, it is all right. As I said, I enjoy building circuits, for long time it has been my work and I had everything I could need in my workshop. Now I deal only with software and all what I have is a soldering iron and a multimeter. If I was not able to find it in the market I was to build it. But I have neither time nor tools, and I think €40 is a reasonable price, I hope it will work, I am still choosing one.
When I started with my Aximizer, putting to work OBD interface was just a game, a way to put to work all Axim interfaces at a time. But once I used my interface with a laptop and I have seen all information it provides, I just can say: I want it in my PDA.
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Any serial port or car diagnostics guru?
