July 2020 - OvmsDev - Open Vehicles

Netmanager priority issue solved
by Michael Balzer 05 Jul '23

05 Jul '23

TL;DR: you need to pull my latest esp-idf changes. I've finally found & solved the strange priority changes for our netmanager task (i.e. being raised suddenly from origin 5 to 18/22): the bug was in the esp-idf posix threads mutex implementation. I had suspected the mutex priority inheritance for a while, so added a way to retrieve the internal mutex hold count for our task list. Using this I noticed the hold count would always & only raise by 2 whenever any kind of mongoose connection was closed. That lead me to checking the thread concurrency protection for mongoose mbufs, because every mongoose connection has two mbufs associated (rx & tx), each having a posix mutex. The bug was: posix mutexes were deleted after locking (taking) them. FreeRTOS mutexes must not be deleted while being taken, that breaks the priority inheritance (more precisely the disinheritance), with the visible effect being the mutex hold count not returning to zero. As a side effect, this may also solve the strange event task starvations (hope so…). I was investigating this as I suspected some busy loop in the netmanager context. With the netman running at prio 22, that would effectively block almost all other processing including the timer service. I've found & fixed one potential busy loop trigger in the netman that would have been caused by the netman task still running while all interfaces had been lost -- not sure if that could happen, but it would explain the effects. So please watch your crash debug info & report if the issue still turns up. Regards, Michael -- Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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ESP32 CAN controller hardware bug / interrupt issue
by Michael Balzer 03 Apr '21

03 Apr '21

Second finding & commit: TL;DR: * ESP32 CAN controller is broken, delivers trashed & duplicated RX frames * we need to optimize interrupt latency Users have been reporting occasional false BMS readings on the Twizy for more than a year. The error always trashed the reading of voltage #10 and/or temperature #8, so I initially thought that must be a variant of the SPIRAM/cache bug. But the SPIRAM fix didn't help, and the bug still occured with all BMS data in internal RAM. The issue correlated with high load situations and the SIMCOM UART issue. On testing the latest changes by Marko, my car module began showing that issue regularly, so I could take a closer look. It turned out the wrong data came from the CAN bus. Checking with a CAN logger didn't show any wrong data on the bus. So I scanned our CAN driver for potential issues, found & solved some (even a serious race condition) but that didn't fix it. I then added debug dumps of all frames read, dug into the SJA1000 spec sheet and found this: The SJA1000 RX FIFO has a capacity of 64 bytes. It's supposed to work as a ring buffer, with frames wrapping around as necessary. If no space is left in the FIFO for a new frame coming in, that frame should be discarded completely, not counted, just the overflow indicator should be set & the according interrupt be generated. Reality differs. The frame causing the overflow is added to the FIFO partially. It's also counted both in the RMC register and indicated by RBS as a valid frame when retrieving the FIFO contents. The read buffer delivers the partial frame + some trashed bytes up to the nominal frame length. In the BMS frame sequence it would normally trash bytes 7 & 8 on the sixth frame of length 8 in a sequence. A standard frame needs a 3 byte header + the data bytes in the FIFO, so 6 frames would add up to 66 bytes => 64 + 2 trash. The first trash byte normally is "08", the second "84" or "2a" or sometimes "ab", possibly some internal SJA1000 data. Better yet, if you rely on the indicators of the SJA1000 when reading the FIFO, the SJA1000 will repeat the first frame within the FIFO after the invalid frame. Mostly once or twice, and sometimes 7 times or more: inv_msg: framecnt=13, invindex=6 inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 24 04 00 00 11 40 10 22 37 55 00 37 | 4..?........$....@."7U.7 inv_msg: 25 04 00 00 0a 1b 44 ff fe 4e 01 26 | 4..?........%.....D..N.& inv_msg: 54 05 00 00 37 37 37 37 37 37 37 00 | 4..?........T...7777777. inv_msg: 56 05 00 00 31 63 14 31 53 14 31 4a | 4..?........V...1c.1S.1J inv_msg: 57 05 00 00 31 43 14 31 53 15 *08 2a* | 4..?........W...1C.1S..* ^^^^^ trashed bytes … followed by 7 repetitions of the first frame: inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n inv_msg: 55 01 00 00 07 98 50 54 54 20 00 6e | 4..?........U.....PTT .n If you had occasional strange false readings leading to strange effects, this may be the explanation. Note: the SJA1000 FIFO bug may need specific circumstance to occur in addition to the overflow, maybe the overflow happening on a specific byte position in the FIFO -- I haven't tried to determine that. I've tried clearing the overflow ASAP, looping on the IR indicator and looping on the RMC, the fault is always the same. The workaround I've now done is adding up the message lengths read during a FIFO run and discard all frames exceeding the 64 byte border. Not pretty, but functional. That keeps the trashed frames from being forwarded to the OVMS application level. As with the SIMCOM UART, these overflows wouldn't happen if the interrupt handler would react fast enough. It seems we've got a general interrupt latency issue. And just as with the SIMCOM I saw a reduction of overflows when allocating the CAN IRQ on core #0, another one with raising the IRQ level to 3, so that's also part of my commit. The esp-idf CAN driver apparently has the same issue even in the latest release, I'll contact the author about this or post another issue to Espressif. So our interrupt allocation is now: Task Run# Lvl ISR# Usage Source ---------------------------------------------------------------------------------------- - 0 1 0 RTC Core ETS_RTC_CORE_INTR_SOURCE esp_timer 0 1 0 RTOS esp_timer ETS_TIMER2_INTR_SOURCE ipc0 0 1 0 RTOS Scheduler Core0 ETS_FROM_CPU_INTR0_SOURCE ipc1 1 1 1 RTOS Scheduler Core1 ETS_FROM_CPU_INTR1_SOURCE main 0 1 0 RTOS Watchdog ETS_TG0_WDT_LEVEL_INTR_SOURCE OVMS Events 1 1 1 Peripherals (GPIO ISR) ETS_GPIO_INTR_SOURCE OVMS Events 1 1 1 MAX7317 (spi_nodma) ETS_SPI3_INTR_SOURCE *esp32can init 0 3 0 ESP32 CAN ETS_CAN_INTR_SOURCE** **OVMS SIMCOM 0 2 0 SIMCOM UART ETS_UART1_INTR_SOURCE* OVMS Events 1 1 1 USB console (UART) ETS_UART0_INTR_SOURCE OVMS Events 1 1 1 SD card ETS_SDIO_HOST_INTR_SOURCE ---------------------------------------------------------------------------------------- I think we need to find the source of the interrupt latency and/or find some better scheme to distribute the tasks & interrupts over the cores. I still don't know why core #1 already got an issue with just our 6 interrupts. This may be related to the SPIRAM fix adding overhead, but I've seen the FIFO overflows before applying the fix, and the CAN issue also has been present for over a year. My working hypothesis is some task/driver disabling interrupts for too often / too long, or non-IRAM ISRs getting delayed for too often / too long. And it seems this is an issue especially on core #1. Please verify & comment. Regards, Michael PS: a little side mystery: the netmanager task starts with priority 5, then gets raised to 22 (probably a mutex priority inheritance), but never gets lowered back to 5 afterwards. A FreeRTOS bug? -- Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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ELM327 codes to
by Soko 27 Nov '20

27 Nov '20

Heya, Another thing I can't figure out at the moment. I have to poll the VWeUp and I figured out (hopefully) how to do that. But I have no clue how to translate the "usual" ELM327 Header+PID to one entry for the OvmsVehicle::poll_pid_t The only value I've understood is the polltime. On my OBD2 interfaces I use a PID of 0x22028C for SoC. But PID is here only 16 bit! Where do I put the header 7E5? What is txmoduleid and rxmoduleid? I can't believe that I'm the first one with this issue ;) Couldn't find any doc though :( So I'm very thankful for any pointing in the correct direction/doc/example. thanks Soko

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Plugin Repository
by Mark Webb-Johnson 20 Oct '20

20 Oct '20

I feel that our plugin system offers a missed opportunity. By making small extensions to available functionality, we can use this system to do so much - and with a much lower complexity and barrier to entry compared to C++ ESP IDF development. There are a couple of things I would like to now do: Implement a mechanism for plugins to directly extend the console command language (other than the current ’script exec PLUGIN.fn’). Implement a plugin repository, and command line tools for managing plugins. We simply need to have a store and directory of available plugins, a way of searching/listing those, and a uniform way to install/remove plugins. Once this is done, perhaps someone can handle the web UI side of this, and perhaps that can even be done as a plugin :-) I’m already working on #1. Just an extension to the existing script system to allow plugins to register commands, and to have the command register/deregister done automatically on plugin load/unload. However, #2 is a little more tricky and I’m looking for feedback on the design of this. My idea is: Store the plugins in a new github/openvehicles/Open-Vehicle-Monitoring-System-3/plugins folder. Eventually the /plugin folder will all be migrated to here. Each plugin has a unique name; the directory in /plugins. Within each plugin directory, there is a <name>.json file (JSON format) with defined tags to describe the plugin. If the plugin delivers a web extension, that is in the ‘web’ subdirectory. If the plugin delivered a script extension, that is in the ’script’ directory. Documentation (in rst format) is in the ‘docs' directory. The JSON file would need the following, at a minimum: Name: The plugin ID Title: One line title Group: Group for the plugin Version: The version string of the plugin Description: Longer textual description of the plugin Prerequisites: Prerequisites to be checked (Each plugin installed provides name=version, the system provides system-level ones such as the version of firmware, and then the prerequisites is simple a list of <name><operator><version> as required) We can automatically build the documentation, and list, for all plugins for our docs.openvehicles.com <http://docs.openvehicles.com/> (in a similar way to how it is done for /plugin now). On a repository server, as part of a nightly build job, we can automatically build a single directory JSON file from the <name>,json descriptors. We can publish this, as well as a git export/checkout of the plugins, on a http download site. On the module, we can store a list of repository servers (allowing the user to add/remove as they require). Contributors/authors of plugins simply GitHub clone our repository, and issue pull requests as appropriate. They can also have their own private repository servers (just need to host the directory json file and associated code files) and add it to their modules. The ‘plugin’ command tree on the module will provide commands for: List installed repositories Add a new repository Remove a repository List installed plugins List/Search available plugins Install a plugin Remove a plugin Update a plugin I would like to try to unify the web and script plugin systems a bit more closely. They are really two sides of the same coin (with some plugins providing both). Does that make sense? Any suggestions/comments? Regards, Mark.

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Duktape Persistent Function References
by Mark Webb-Johnson 28 Sep '20

28 Sep '20

@Michael this is probably for you. I am trying to implement javascript command registration. The idea is that a javascript module can call something like: OvmsCommand.Register(basecommand, name, title, callbackfn, usage, min, max) Then we reflect that into MyCommandApp.RegisterCommand, and keep a track of which command is for which javascript callbackfn. When the command is executed, we pass it into duktape. I also have tracking for javascript module loading and unloading, so I can DeregisterCommand() if duktape is reloaded (and also protected against commands being registered in short-lived scripts run from the command line). To implement this, I need to store the callbackfn as a persistent reference to a duktape javascript function. The issue with callback function references in duktape is summarised here: https://wiki.duktape.org/howtonativepersistentreferences <https://wiki.duktape.org/howtonativepersistentreferences> When a Duktape/C function is called, Duktape places the call arguments on the value stack. While the arguments are on the value stack, they're guaranteed to be reachable and the Duktape/C function can safely work with the arguments. However, when the Duktape/C function returns, the value stack is unwound and references in the function's value stack frame are lost. If the last reference to a particular value was in the function's value stack frame, the value will be garbage collected when the function return is processed. The standard approach is to store the reference back in the duktape duk_push_global_stash so it won’t get garbage-collected. But, that seems messy. I see that Michael has already implemented something that seems similar in ovms_script.{h, cpp}, for the async http callbacks. Presumably to avoid this issue. But, the approach seems very different, and I am not sure if it is stopping _all_ garbage collection for the duration of the async query, or just that particular object being garbage collected. The work seems extensive (quite a few objects involved). So @Michael, any suggestions for this? I don’t want to reinvent the wheel... Regards, Mark.

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Hacking TPMS
by Mark Webb-Johnson 25 Aug '20

25 Aug '20

I’ve been spending the last month or so hacking away at TPMS. This has been an ongoing project for the Tesla Roadster that is finally coming to fruition. About a year or so ago, we already made changes to: Modify the Tesla Roadster cable to connect the k-line pin on the diagnostic connector through to the DB9 connector on OVMS. We labelled this cable ‘OVT1’. Modify the OVMS module to connect that k-line pin to GEP7. I’m now working on an optional expansion board that will include a little TJA1027T transceiver and map it to EXP1 and EXP2 (for async comms) and EGPIO8 (for enable/disable) on the ESP32 and MAX. This board will include a jumpered option for K-line master (one diode + one resistor), as well as jumpered powered selection (5v from usb, 5v regulated from car 12v, or direct car 12v) for the K-line bus. The hand-soldered prototype, using our breakout boards, works well and the K-line async comms works. The screenshot shows OVMS sending a 19 byte request to the ECU (0x0f 0x04 .... 0xf0) and the ECU responding 19 bytes (0x0f 0x05 ... 0xf0) with the 4 tyre IDs. There is a similar command to re-program the ECU with new IDs. On the firmware side, I am implementing a new vehicle independent ’tpms’ subsystem within OVMS (enabled via configureable option). This will allow sets of tyres to be maintained in the config and read/written to the car's TPMS ECU. The following commands will be available: tpms status - show status of the system tpms list - list tyre id sets in config tpms read <set> - read IDs from tpms ecu and store in config tyre set tpms write <set> - write IDs to toms ecu from config tyre set tpms set <set> {<id>} - config a set of IDs manually tpms delete <set> - delete the specified tyre set The initial version will support Tesla Roadster, but the functionality is there for other vehicles to use if they need it (in particular for standard K-line implementations). Comments/suggestions welcome. Regards, Mark. +++Attachments+++ Bench setup, showing (from left to right): Tesla Roadster TPMS ECU opened up Breakout board (power, k, Lin, and can) OVMS for can decode Usb logic analyser Power supply (12v) K-line analysis tool (9010) Windows laptop running k-line software Mac running logic analyser and terminal to OVMS. Hand-soldered prototyping board Async comms over k-line.

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Vehicle Idle Notification
by Derek Caudwell 01 Aug '20

01 Aug '20

Hi all, In Vehicle.cpp the NotifyVehicleIdling() routine is essentially called when StdMetrics.ms_v_env_awake is true and the idle ticker has expired. My understanding from the standard metrics documentation is that the awake metric is to indicate activity on the can bus eg when charging or prior to the vehicle being turned on. Hence I was only expecting an idle notification if the vehicle has been accidentally left in the on state indicated by StandardMetrics.ms_v_env_on. Or have I misunderstood how the two metrics and idle function are intended to work or mean? Cheers Derek

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App for Garmin Watches
by Sébastien Darveau 31 Jul '20

31 Jul '20

Hi Mark, I’m working on a widget to see my SOC on my Garmin watch and I’d like to request permission to go further and publish on the Garmin store (https://apps.garmin.com/en-US/) with “OVMS" as name. Once in the store, user will be able to enter vehicle_id, username and password/token to access own car information. Application uses a proxy on AWS Lambda to access the REST Api. I have taken the resources from the iOS app and reduced the size a bit. Please note that I also use the OVMS logo on the loading screen. Here is the code: https://github.com/sdarveau/Open-Vehicle-Garmin. Feel free to move it under the openvehicles workspace. I’m planning to improve it but I'll keep it simple. Thanks, Sebastien

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Reading config in OvmsVehicleXXXInit
by Soko 26 Jul '20

26 Jul '20

Hey guys, I'd like to keep the sources for the T26A and OBD version for the VW e-up separated. With my little understanding of the OVMS framework I've created one (abstract) class for the vehicle with the web-interface stuff. Then two derived classes, one for OBD one for T26A. Now I try to register those two different classes depending on the settings: OvmsVehicleVWeUpInit::OvmsVehicleVWeUpInit() { int how_connected = MyConfig.GetParamValueInt("vwup", "how_connected", CONN_OBD); ESP_LOGI(TAG, "Registering Vehicle: VW e-Up (9000). how_connected=%d", how_connected); if (how_connected == CONN_T26A) { MyVehicleFactory.RegisterVehicle<VWeUpT26a>("VWUP", "VW e-Up"); } else { MyVehicleFactory.RegisterVehicle<VWeUpObd>("VWUP", "VW e-Up"); } } I know already that this only gets called during reboot as the log-message doesn't show up when I change the vehicle. But it seems that MyConfig isn't really the correct/same instance (?) as I'm getting inside my classes. Because the web-interface shows how_connected=CONN_T26A, but here it is always CONN_OBD (default value). How do I do this properly? Or is it even a better idea to do two separate vehicles?? thx Soko

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Re: [Ovmsdev] debugging CAN bus error flags
by Derek Caudwell 19 Jul '20

19 Jul '20

Thanks Michael, That explains why I was struggling to decode the error flag. Having been through the MCP2515 docs and decoded the logged error flags can2 is receiving they all relate to overflow of RXB0 but not RXB1. Hence this does not really pose or indicate a problem for the can bus / MCP2515 chip, correct? So if I have understood the chip operation is there any reason for line 489 in mcp2515.cpp which causes these to be logged? 489: LogStatus(CAN_LogStatus_Error); As if RXB1 does overflow and cause a packet loss then line 467: ESP_LOGW(TAG, "CAN Bus 2/3 receive overflow; Frame lost."); deals with that? Cheers Derek

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