Question regarding NoteStatus 341

[bernha...@googlemail.com]

Hi,
Ist will start with UAVCA but with the first message ich have already a Problem.

I will develop a simple temperature sensor with a Stm8 Prozessor.

I found in the Document "List of standard data types" the following fields for the NoteStatus 341.

-uint16 MAX_BROADCASTING_PERIOD_MS = 1000
-uint16 MIN_BROADCASTING_PERIOD_MS = 2
-uint16 MIN_BROADCASTING_PERIOD_MS = 2
-uint16 OFFLINE_TIMEOUT_MS = 3000
-uint32 uptime
-uint8 health
-uint8 mode
-uint16 vendor_specific_status_code
-Tail

If ich take a look into the simple Example ich found only the fields
-Health
-Mode
-Vendor_specific_status_code
-Tail
Together > 7 Bytes

Im not sure sure that ich should implement ich my system?
I prever the short messages.

Regarding

Bernhard

[Pavel Kirienko]

Hi Bernhard,

 

Which example are you referring to? Is it the "simple sensor node example" published at http://uavcan.org/Examples/Simple_sensor_node/?

 

The tail byte is a crucial part of the transport layer. A single CAN 2.0 A/B frame can accommodate up to 8 bytes, 1 of which is used by the tail byte, which leaves us with 7 bytes for the payload. Taking the NodeStatus message as an example, we see that its size is fixed at 7 bytes indeed; adding the tail byte we get an 8 byte sized payload that fits into a single CAN frame.

 

Perhaps I failed to answer your question adequately; if so, could you please clarify which part is unclear?

 

-- 

Pavel Kirienko

+7 926 253 2081

Zubax Robotics OÜ

 

 

 

22.07.2017, 16:18, "bernhardnikl via UAVCAN" <uav...@googlegroups.com>:

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[bernha...@googlemail.com]

Thanks for the answer.
Yes i mean the sample.
If ich look in the "List of standard data types" i found a lot of more data fields for 341.
Is somewhere a other source for the structure of the messages?

Regards

Bernhard

[Pavel Kirienko]

The additional fields are constants, they do not affect the binary layout and are never exchanged over the bus. You can find more background information on the topic in the third chapter of the specification: http://uavcan.org/Specification/3._Data_structure_description_language/

 

Both definitions you referred to are fully compatible and equivalent.

 

-- 

Pavel Kirienko

+7 926 253 2081

Zubax Robotics OÜ

 

 

 

22.07.2017, 19:20, "bernhardnikl via UAVCAN" <uav...@googlegroups.com>:

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[bernha...@googlemail.com]

Hi Pavel,

Ahhhh.
Now i unterstand. ;-)

Sorry, i 'm a little bit confuse.

In case of 1110.
2 byte device_id
2 byte temperature
1 byte error_flag
1 byte tail

Thanks a lot

Regards

Bernhard

[Pavel Kirienko]

Yes, the layout you posted looks correct.

 

You can get a hands-on experience with the UAVCAN GUI Tool. It has a CAN bus monitoring and decoding utility that should help you better understand the protocol.

 

-- 

Pavel Kirienko

+7 926 253 2081

Zubax Robotics OÜ

 

 

 

22.07.2017, 21:20, "bernhardnikl via UAVCAN" <uav...@googlegroups.com>:

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