Quote:
Originally Posted by njakts
what must be done to try 14230 protocol?
I am quite dumb in software level. I have no idea how the program works  |
I hope you haven't given up. It appears there's an OBDuino support drought recently.
You'll need to take a look in the source and find the following code:
Code:
// Uncomment only one of the below init sequences if using ISO
#define ISO_9141
//#define ISO_14230_fast
//#define ISO_14230_slow
This is the default configuration in trunk - iso9141. To try the other protocols place a single line comment (two foreslashes) in front of the #define ISO_9141 and remove the comment from one of the other two to try a different iso protocol. Upload to your atmega and give each protocol a try.
Also, if you're using schlorkist's voltage comparator circuit, I found that a small revision was necessary in order for switching of the RX side, this could very well be your issue also. I had to remove the interconnect from pin 6 to pin 5 and create a separate voltage divider that floats this input closer to 3 volts (I had a 4.1k and a 12k resistor handy, which happened to work). If you're not sure what I'm getting at here don't hesitate to ask and I'll try to draw up a schematic.
An easy way to test whether the RX comparator channel is functioning properly is to use a multimeter and watch the output of the LM339 channel 2 (pin 1). If it's at or near 0 volts the majority of the time you have the same problem I did. When the voltage divider is right you will see the output of channel 2 hover around 5 volts most of the time and then pulse near 0v when the iso init routine sends the 5 baud request. This should happen in unison with the K-Line output on the collector of Q1 (measure on pin 7 of the LM339). I'm not sure if this is a flaw in schlorkist's design, or possibly a difference in comparator sensitivity. I wonder if he would care to chime in about this in case he made revisions to the circuit that weren't posted.