Charles,
'Sent' protocol is time based with a
data tick at 15us !!!
While it remains theoretically possible
to process this on pure vanilla Linux with a simple GPIO, such a
decoding model would consumes far too many CPU to be viable.
Outside of a hobby/student proof of concept[1], I do not see how
decoding 'Sent' protocol directly within Linux would make value in
a real project. One option to avoid dedicated 'Sent' hardware
could be to delegate 'Sent' protocol decoding to the MCU present
within any modern SoC (Renesas, Ti, NXP, ST, etc). Asymmetric
multi-core architecture permits to run a pure RTOS as Zephyr
alongside Linux on the same SOC. With such a model you may use the
MCU and Zephyr to decode the 'Sent' protocol and Linux on the
A-cores to process already decoded frames.
Renesas as an ongoing demonstration at
CES-2023 where they demonstrate Linux and Zephyr on the same SoC.
While current Renesas R-CAR demo uses Zephyr to decode CAN frames
the Linux/RTOS collaboration model remains valid for an other
protocol. Note that we also gave a presentation on similar topic
at ALS-Japan[2]
Fulup
On 22/12/2022 14:36, Jan Simon Moeller
wrote:
Hi Charles,
welcome to AGL and thanks for posting. I've added a few remarks and pointers below:
we are currently implementing different applications using AGL to read values from typical powertrain related sensors and control powertrain actuators (EGR Valve, HFM Sensor, Lambda Sensor, Temperature / Pressure sensors, etc.).
We do currently expose data through VSS/VISS (https://www.w3.org/auto/wg/wiki/Vehicle_Signal_Specification_(VSS)/Vehicle_Data_Spec)
by the use of KUKSA.val . So we do feed data into KUKSA.val e.g. by CAN bus.Using a feeder you can also add more sensors here.
We would like to be able to read values from SENT protocol based sensors as their use has become quite widespread in powertrain applications. So we would like to know if there is already any implementation of the SENT protocol within AGL?
As far as I can see there is no support in the Linux kernel atm. I found references for GPIO implementations (aka bit-banging) like here:
Now it depends if bit-banging in a user-space implementation would do it for the use cases you have or if you have very tight timing restrictions.In the latter case there would be work to do to either enhance a user-space implementation with faster kernel interfaces or do a driver in the linux kernel right away. In any case, there is work to do.
AGL can be a home for a collaboration effort for your contributions and contributions for other interested parties.
We do have a weekly developer call - next one will be in January. Watch this space for updates:https://lists.automotivelinux.org/g/agl-dev-community/calendar as the date might move a day.
Best regards,
Jan-Simon
------
Jan-Simon Möller
AGL Release Manager
The Linux Foundation
Visit us at:
www.automotivegradelinux.org
lists.automotivelinux.org
www.linuxfoundation.org
On Tue, Dec 20, 2022 at 11:54 AM Carles Sole via lists.automotivelinux.org <Carles.SoleMendi=de.bosch.com@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hello all,
we are currently implementing different applications using AGL to read values from typical powertrain related sensors and control powertrain actuators (EGR Valve, HFM Sensor, Lambda Sensor, Temperature / Pressure sensors, etc.).
The HW relevant signals / protocols we are using so far:
- PWM, Spi, ADC, DAC, CAN.
We would like to be able to read values from SENT protocol based sensors as their use has become quite widespread in powertrain applications. So we would like to know if there is already any implementation of the SENT protocol within AGL?
Else we would try and implement it from scratch.
Best Regards,
Carles
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