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ovmsdev@lists.openvehicles.com

October 2022

11 participants
22 discussions

OBDII vehicle chicken-n-egg issue
by Craig Leres 03 Oct '22

03 Oct '22

I cloned the OBDII module when I started work on the C6 Corvette and 2nd gen CTS modules. Trying to debug my C6 Corvette canbus issues I'm not understanding how OBD polling works. What I see when I look at vehicle_obdii.cpp is that there is a list of pids that are polled. However, OvmsVehicleOBDII::IncomingPollReply() is the only place that *enables* polling: case 0x0c: // Engine RPM if (value2 == 0) { // Car engine is OFF PollSetState(0); StandardMetrics.ms_v_env_handbrake->SetValue(true); StandardMetrics.ms_v_env_on->SetValue(false); StandardMetrics.ms_v_pos_speed->SetValue(0); StandardMetrics.ms_v_env_charging12v->SetValue(false); } else { // Car engine is ON PollSetState(1); StandardMetrics.ms_v_env_handbrake->SetValue(false); StandardMetrics.ms_v_env_on->SetValue(true); StandardMetrics.ms_v_env_charging12v->SetValue(true); } break; I can only assume "engine RPM" canbus frames are always sent by the vehicle (not unreasonable); but then I don't understand why we are polling for it? I guess I would expect ms_v_env_on state changes to happen in SOvmsVehicleOBDII::IncomingFrameCan1(). But maybe OvmsVehicleOBDII::IncomingPollReply() gets engine RPM frames since they are on the list of things we're polling for? So if we didn't handle them in IncomingPollReply() we'd have to add a IncomingFrameCan1() routine? Playing around with savvycan I find it's possible to have the C6 Corvette, with engine running, to not be "on" but still send canbus frames to savvycan (at least until *it* gives up and disconnects). This makes me think I'm getting into a situation where ovms does not detect that the car is on but not because the canbus is not working due to logic errors on my part. Certainly "can can1 status" reports a similar number of tx fails when compared to my working vehicle (2nd gen Cadillac). Craig

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savvycan foo
by Craig Leres 02 Oct '22

02 Oct '22

I clearly do not understand how to drive savvycan. I have two versions on a windows 10 laptop: ?, self identifies as V203, circa April 2021 1.0.245, self identifies as V204, circa May 2021 Connecting is very problematic. I started with my Cadillac which "works". As per the documentation I started with: can log start tcpserver discard gvret-b :23 I was never able to connect with the May version. (Meanwhile, the FreeBSD version 1.0.245 port "works" as well as the Windows May executable... BTW, I'm the port *maintainer* for this!) With the older, April version I can sometimes connect but it's painful; if anything goes wrong or once it disconnects, I do not know how to reconnect, the *only* option appears to be to delete the device and add it back... In the rare cases I was able to connect (to a vehicle with an ovms module that I have started a tcpserver on, and the engine running) it *always* disconnects after N frames are received (about 125K for the Cadillac). It's like it fills up a buffer and quits. As stated, I do not understand how to drive this tool. The 2nd gen CTS has two buses: a canbus @ 500k and a single wire canbus @ 33.333k. Is it really not possible to configure the buses to *different* speeds? (And if gvret-b allows savvycan to know how many buses the network device has why doesn't it know what their respective speeds are? And why is 33.3333 missing?) Sorry for ranting about savvycan issues on the ovmsdev list but I have to believe some of you folks understand how make it do something useful. Craig

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