[Ovmsdev] OVMS Poller module/singleton

Sun Jan 19 20:39:48 HKT 2025

Hi,

Am 19.01.2025 um 12:48 schrieb Michael Balzer via OvmsDev:
> Regarding CAN timing, our ESP32CAN/SJA1000 configuration is mostly according to the SAE/CiA recommendations, with one exception: we generally enable multi (triple) sampling, regardless of the bus speed:
>
> esp32can::InitController():
> […]
>   /* Set sampling
>    * 1 -> triple; the bus is sampled three times; recommended for low/medium speed buses     (class A and B) where filtering spikes on the bus line is beneficial
>    * 0 -> single; the bus is sampled once; recommended for high speed buses (SAE class C)*/
>   MODULE_ESP32CAN->BTR1.B.SAM=0x1;
>
> SAE defines "high speed" (class C) as speeds >= 125 kbit/s. See SAE J2284-1, -2 & -3, section 6.10.8 Data Sample Mode: "The data sampling shall always be set to single sample mode."
>
> If setting SAM=0 for 500 kbit/s, our timing setup is exactly as recommended by two tested SJA1000 timing calculators on the web.
>
> Maybe we should give that a try? I.e.
>
>   MODULE_ESP32CAN->BTR1.B.SAM = (MyESP32can->m_speed < CAN_SPEED_125KBPS) ? 1 : 0;
>
> Simon, can you try if that helps?

I have adjusted the corresponding line.
I will check tomorrow whether this has an effect on the active mode.
I tried your recommendation and set the CONFIG_OVMS_VEHICLE_CAN_RX_QUEUE_SIZE to both 200 and 400. I have not yet checked whether the bus also crashes in active mode. However, I can see in listening mode that when I abort a running loading process (there are currently no overflows), many overflow messages are received.

> But as you also use can2, I wouldn't rule out a timing issue with the MCP2515 configuration. At which speed do you have can2, and did you have some indication from the vehicle error codes regarding a specific bus?
RegisterCanBus(1, CAN_MODE_LISTEN, CAN_SPEED_500KBPS);
RegisterCanBus(2, CAN_MODE_LISTEN, CAN_SPEED_125KBPS);
I do not receive any feedback from the car as to which bus is affected, unfortunately no error code is saved for the incident. Do you have the option of specifying the affected bus in the overflow logging?

Cheers,
Simon
>
>
> Am 17.01.25 um 17:49 schrieb Michael Balzer via OvmsDev:
>> OK, I've got a new idea: CAN timing.
>>
>> Comparing our esp32can bit timing to the esp-idf driver's, there seem to be some differences:
>> https://github.com/espressif/esp-idf/blob/master/components/hal/include/hal/twai_types_deprecated.h#L75
>>
>> Transceivers are normally tolerant to small timing offsets. Maybe being off a little bit has no effect under normal conditions, but it has when the transceiver has to cope with a filled RX queue. That could be causing the transceiver to slide just out of sync. If the timing gets garbled, the transceiver would signal errors in the packets to the bus, possibly so many the vehicle ECUs decide to raise an error condition.
>>
>> Is that plausible?
>>
>> On why the new poller could be causing this (in combination with too slow processing by the vehicle): as mentioned, the standard CAN listener mechanism doesn't care about queue overflows. The poller does. `OvmsPollers::Queue_PollerFrame()` does a log call when Tx/Rx tracing is enabled, that could even block, but tracing is optional and only meant for debugging. Not optional is the overflow counting using an atomic uint32.
>>
>> The atomic types are said to be fast, but I never checked their actual implementation on the ESP32. Maybe they can block as well?
>>
>> @Simon: it would be an option to try commenting out the overflow counting, to see if that's causing the issue.
>>
>> Regards,
>> Michael
>>
>>
>> Am 17.01.25 um 15:37 schrieb Chris Box via OvmsDev:
>>>
>>> Yes, I can confirm I've had one experience of the Leaf switching to Neutral while driving, with a yellow warning symbol on the dash. It refused to reselect Drive until I had switched the car off and back on. Derek wasn't so lucky and he need to clear fault codes before the car would work.
>>>
>>> On returning home, I found OVMS was not accessible over a network. I didn't try a USB cable. Unplugging and reinserting the OBD cable caused OVMS to rejoin Wi-Fi. However the SD logs showed nothing from the time of the event. CAN writes are enabled, so it can perform SOC limiting.
>>>
>>> My car has been using this firmware since 21st November, based on the git master of that day. As a relatively new user of OVMS (only since October) I don't have much experience of older firmware.
>>>
>>> Perhaps a safeguard should be implemented before releasing a new stable firmware that will be automatically downloaded by Leaf owners. But I don't have the expertise to know what that safeguard should be. Derek's suggestion of 'only CAN write when parked' appears to be a good idea.
>>>
>>> Chris
>>>
>>>
>>> On 2025-01-15 18:18, Derek Caudwell via OvmsDev wrote:
>>>
>>>> Since the following email I have high confidence the issue on the Leaf is related/caused by the poller as there has been no further occurrence and Chris has also experienced the car going to neutral on the new poller firmware.
>>>>
>>>> ....
>>>> I haven't ruled out it being a fault with my car yet. Shortly after it faulted the car was run into so has been off the road for sometime, my first step was to replace 12V battery. The ovms unit is now unplugged and if it does not fault over the next month while driving I'll be reasonably confident it's ovms related.
>>>> Not sure which firmware version the poller updates were included in but it was only after upgrading to it that the errors occurred (which could be coincidental however it has faulted twice more both on version 3.3.004-141-gf729d82c). For periods where I reverted to 3.3.003 it was fine.
>>>> It might be useful to have an extra option on the enable can write to only enable it when the car is parked/charging.
>>>>
>>>
>>>
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>>
>> -- 
>> Michael Balzer * Am Rahmen 5 * D-58313 Herdecke
>> Fon 02330 9104094 * Handy 0176 20698926
>>
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>
> -- 
> Michael Balzer * Am Rahmen 5 * D-58313 Herdecke
> Fon 02330 9104094 * Handy 0176 20698926
>
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