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Something is fishy and I want to clear this one up! How can one be sure to get a good cable from a seller on eBay or Amazon, if the pics look all the same? Example: one of the recommended Amazon sellers has pictures showing the white PCB with the big fat 7805 on it. What do the expensive cable have, which the cheap ones don't? Better quality control? I read all existing posts on all relevant forums about these white PCB cables and one thing that annoys me is that people do not give any feedback on how the story ended!Īlso, I am annoyed to see that apparently the same cable is sold from 15 Euro to 65 Euro! They all look the same, except some are white PCB, others are green PCB. I'm tired now, but I will investigate further. This is not a problem with the PC to FTDI chip connection, but rather from the FTDI chip to the Atmel. I believe that there is something preventing the FTDI chip to talk to the Atmel controller. I'm not swapping the diode, as I think this is not the bad component. There is a diode close by, an SS14, which I suspected could be dead, but using a simple measurement, it seems to be OK, delivering the same aproximate results as a similar working SS14 on an old motherboard. The reason seems to be the evolved architecture: the interface started out as a pure RS-232 interface, the FTDI 232-to-USB has been added later. These are powered by the car and not by the USB port. This is used to provide stable 5V to the Atmel controllers. even worse than I thoughtħ805 voltage regulator indeed. Seems that the big thing is a power regulator to obtain the 5V.
I hope the link is not against any forum rule. I just need to know what the good diode/transistor reference is.
I believe this is the culprit of all faulty cables and an easy soldering job. What is the reference on the small transistor, which was replaced on the white board with the big one? Perhaps the specs are out of limit. I asume it is powered by the obd2 port and some component on the pcb is broken. The problem is with the communication to the microcontroller (atmel chip i think). This goes straight to the FTDI rs232 to usb converter. The cable consists of a microcontroller that implements the k+dcan protocol and has a rs232 interface for pc communication.
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