<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div>Avesh,</div><div><br></div><div>That's correct, the ATMA command will spew messages that match your filter (or all messages if you set the CAN filter mask to 000: ATCM 000) until you type a character to interrupt it. I usually hit space or return.</div><div><br></div><div> Tom</div><div><br></div><span id="OLK_SRC_BODY_SECTION"><div><div>On 2/10/14, 11:05 PM, "Avesh Chauhan" <<a href="mailto:aveshcool@gmail.com">aveshcool@gmail.com</a>> wrote:</div></div><div><br></div><div dir="ltr">Dear Tom,<div><br></div><div>Thanks for so nicely explaining your work. I tried almost similar steps using wifi enabled ELM 327 chipset on my car ( not a electric car ). However did not use the command Can Mask command you suggested . This is useful as with ATMA command , OBD adapter is not able to provide all data so filtering the data is awesome idea.So i believe it will continue to monitor particular parameter unless interrupted ???</div><div><br></div><div>@ Dear Mark and all :</div><div><br></div><div>have you guys worked on ELM 329 chipset. I am not able to understand the difference between ELM 327 and 329. Any help is appreciated .</div><div><br></div><div>Regards,</div><div>Avesh</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Feb 11, 2014 at 7:20 AM, Tom Saxton <span dir="ltr"><<a href="mailto:tom@idleloop.com" target="_blank">tom@idleloop.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-size:14px;font-family:Calibri,sans-serif;word-wrap:break-word"><div>I bought a tiny $12 ELM327 Bluetooth gizmo that's listed among the devices compatible with LeafSpy.</div><div><br></div><div><a href="http://www.amazon.com/gp/product/B008U1MOM8/" target="_blank">http://www.amazon.com/gp/product/B008U1MOM8/</a></div><div><br></div><div>I also bought the OBDII Y cable that Mark suggested which looks like a high quality cable and it works.</div><div><br></div><div><a href="http://www.amazon.com/gp/product/B00EEDOWU8/" target="_blank">http://www.amazon.com/gp/product/B00EEDOWU8/</a></div><div><br></div><div>At first I had zero success getting CAN messages from the Leaf's CAR-CAN bus using the ELM327; I got either nothing or garbage data with errors and buffer overflow messages. </div><div><br></div><div><div>This tutorial Mark suggested is inspiring, and illustrates a good general technique for figuring things out, but it has no information on how to get CAN data.</div><div><br></div><div><a href="http://theksmith.com/technology/hack-vehicle-bus-cheap-easy-part-1/" target="_blank">http://theksmith.com/technology/hack-vehicle-bus-cheap-easy-part-1/</a></div><div><br></div></div><div>I was then led astray by reading the ELM32X data sheet and the Wikipedia page on how OBDII CAN messages work.</div><div><br></div><div><a href="http://elmelectronics.com/DSheets/ELM327DS.pdf" target="_blank">http://elmelectronics.com/DSheets/ELM327DS.pdf</a></div><div><a href="http://en.wikipedia.org/wiki/OBD-II_PIDs" target="_blank">http://en.wikipedia.org/wiki/OBD-II_PIDs</a></div><div><br></div><div>The specifics of how the messages are formatted is completely wrong for the Leaf. The 11-bit CAN ID values are not used to identify ECUs, they are the message identifiers. Instead of looking at CAN IDs in the range 7E0 to 7EF, you have to look at all CAN IDs from 001 to 7FF.</div><div><br></div><div>The next problem is that there is so much traffic on the Leaf's CAR-CAN bus, that a low-bandwidth unit like the cheap Bluetooth gizmos can't possibly keep up. I was able to determine that the output baud rate on the above gizmo is at most 38400 bps. To look at things, you need to filter to only get a subset of the constant stream of traffic on the CAR-CAN bus.</div><div><br></div><div>The trick is to use the ATCM (CAN mask) and ATCF (CAN filter) commands to filter for a single message. For example, to view message 0x5C5 which includes the Leaf's odometer value, first set up the chip with these commands:</div><div><br></div><div>ATZ</div><div>ATH1</div><div>ATL1</div><div>ATS1</div><div>ATAL</div><div><br></div><div>Those commands in order: reset the chip to defaults, turn on message headers (which show the CAN ID), line endings between messages and spaces between bytes, and enables long messages. Then issue these commands:</div><div><br></div><div>ATCM 7FF</div><div>ATCF 5C5</div><div>ATMA</div><div><br></div><div>The first two commands set the ELM327 to filter for a single message ID, 5C5, the third starts dumping them. You'll get data that looks like this:</div><div><br></div><div><div>5C5 44 00 3C BA 00 0C 00 00</div><div>5C5 44 00 3C BA 00 0C 00 00</div><div>5C5 44 00 3C BA 00 0C 00 00</div><div>...</div></div><div><br></div><div>Type any character to stop the spewing of messages. The first group of three hex digits, 5C5, is the message ID, followed by the message data, bytes 0 through 7. According to the LEAF CAN message spreadsheet, skipping the first byte (44) and taking the next three (00 3C BA) yields the odometer. Sure enough, 003CBA is 15,546 in decimal, which is indeed our Leaf's odometer value.</div><div><br></div><div>I also confirmed the Gid value documented in message 5B3 for several Gid values in the low 200's.</div><div><br></div><div>To get an idea of what's happening on the CAR-CAN bus, I wrote a program that marches though all 2048 CAN ID values, listens for each message ID until either 20 messages have been collected or 2.01 seconds goes by with no messages, then moves on to the next ID. Using that program, I found 49 messages that happen between twice and one hundred times per second when the car is parked and turned on in accessory mode. Together, they total up to over 1500 messages per second. So, you'd need an output baud rate around 500,000 bps to monitor all messages, which is totally not happening with a $12 38400 bps gizmo.</div><div><br></div><div>I've attached a spreadsheet with the list of those messages. I have a text file with 20 sample messages of each type. I'm happy to share if anyone else wants to see it.</div><div><br></div><div><div>See the spreadsheet of known LEAF CAN messages to see what's known about what they contain.</div><div><br></div><div><a href="https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dGRaSWl6VTV2eXBQMy1ON2xZSzlMUXc#gid=1" target="_blank">https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dGRaSWl6VTV2eXBQMy1ON2xZSzlMUXc#gid=1</a></div></div><div><br></div><div>Unfortunately, with the sealed plastic $12 gizmo, there's no way to look at the EV-CAN bus, so that will have to wait until I get a better device. I'm considering these three:</div><div><br></div><div>Mark recommends: <a href="http://www.can232.com/?page_id=16" target="_blank">http://www.can232.com/?page_id=16</a> ($140 + cable + shipping)</div><div>Roadster service techs use: <a href="http://gridconnect.com/can-usb.html" target="_blank">http://gridconnect.com/can-usb.html</a> ($255 + cable + shipping)</div><div>Sparkfun: <a href="https://www.sparkfun.com/products/9555" target="_blank">https://www.sparkfun.com/products/9555</a> ($74.85 with cable and shipping)</div><div><br></div><div>For connecting to the CAN bus, OVMS uses the same pin mapping as the device Mark and Tesla use. Sparkfun uses a different pin mapping which agrees with what OBD2cables.com says is the "de facto standard pinout."</div><div><br></div><div><a href="http://www.obd2cables.com/products/cable-j1962m-right-angle-to-db9f-4-3-ft.html" target="_blank">http://www.obd2cables.com/products/cable-j1962m-right-angle-to-db9f-4-3-ft.html</a></div><div><br></div><div>Standards are so awesome, we have at least two!</div><div><br></div><div>I was surprised to see <a href="http://obd2cables.com" target="_blank">obd2cables.com</a> claiming a standard that's different from what I expected from Mark's and Tesla's preferred gizmos. Fortunately, it should be easy to make a DB9 adapter to convert between the two standards should the need arise.</div><span class="HOEnZb"><font color="#888888"><div><br></div><div> Tom</div></font></span></div><br>_______________________________________________<br>
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