Control Myxa with UART

mah · February 3, 2021, 2:45am

Hi,
I’m trying to control the Myxa with an Arduino over serial. Is there a document somewhere that explains how to format the serial packets and what parameters can be read/written? I couldn’t find what I needed in the knowledge base.

pavel-kirienko · February 3, 2021, 10:48am

Currently, the best we can offer is this:

but we are working on supporting UAVCAN v1 in Myxa, which will be available not only as UAVCAN/CAN but also as UAVCAN/serial via UART and USB.

mah · February 5, 2021, 9:10am

Hi Pavel,
I was able to control the motor and get telemetry over UART by copying the parsers in messages.py in Kucher. However, I can’t find the part where we find part at the very beginning when you get the hardware/firmware version after connecting. Can you point me to the right location to find the correct packet structure?

pavel-kirienko · February 5, 2021, 3:33pm

It’s here:

github.com

Zubax/popcop/blob/master/python/popcop/standard/endpoint_info.py

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mah · February 5, 2021, 7:17pm

Is there a table somewhere to look up the “frame type code”?

pavel-kirienko · February 5, 2021, 7:26pm

For standard messages there is only one frame type code:

https://github.com/Zubax/popcop/blob/f45deea2486fa1d5f18d575c7eba7197bbd22e32/python/popcop/_\_init__.py#L33

For application-specific:

github.com

Zubax/kucher/blob/fced36646d693fbdd6baa30cbcafaae11ef45cdd/kucher/model/device_model/communicator/messages.py#L459-L464


      
          self._type_mapping: typing.Dict[MessageType, typing.Tuple[int, con.Struct]] = {
              MessageType.GENERAL_STATUS:         (0, GeneralStatusMessageFormatV1),
              MessageType.DEVICE_CHARACTERISTICS: (1, DeviceCharacteristicsMessageFormatV1),
              MessageType.COMMAND:                (2, CommandMessageFormatV1),
              MessageType.TASK_STATISTICS:        (3, TaskStatisticsMessageFormatV1),
          }

mah · February 6, 2021, 6:16pm

Thanks, I got it working.

If anyone else needs to control Myxa with an Arduino over UART, I uploaded my code here:

My MCU was the Teensy4.0.

dan · March 21, 2022, 4:49pm

Hi Mah, would you kindly be able to share your python script to control and monitor myxa?

mah · March 21, 2022, 10:54pm

sorry, I never made a python script. the code in the git repo linked is all I have.

denny · July 20, 2022, 11:19am

Hi, mah

Do you use UART using a pin of dronecode probe?
I am using dronecode probe’s 2(Rx) and 3(Tx). problem is your code could not parse the messsage through the pin but I think the message from USB connection is no problem…

AM I something wrong?

pavel-kirienko · July 20, 2022, 3:33pm

Check the serial port settings, they should be 115200 8N1.

denny · July 21, 2022, 1:39pm

Thanks, Pavel

My board is not teensy 4.0 used by man but it is lolin nodemcu v3 esp8266.

I think I should change something to work in my board, but I don’t know what exactly what I do. I am not professional.

Could you let me know what and how to change?

Thanks,

pavel-kirienko · July 21, 2022, 2:48pm

I can’t help with “how” but the “what” is to set the baud rate to 115200, 8 bit word, no parity, one stop bit.

denny · July 22, 2022, 12:50pm

Thanks, I order teensy 4.0.

mah · July 22, 2022, 7:47pm

Hi Denny,
I don’t use the dronecode probe, the debug port is connected directly to the microcontroller. Make sure the settings are like Pavel said and that Rx<->Tx for both lines. Also, when you make an instance of the object you need to indicate the serial ports you want to use. In the example code I was using Serial3 and Serial5 for command/logging, so you need to edit this to make it correspond with the serial port on your device.
For the NodeMCU V3, I think you cna try using Serial0 (GPIO1/3) and Serial2 (GPIO13/15).

denny · July 23, 2022, 10:43am

Hi mah,

Thanks for your reply.

NodeMCU V3 doesn’t have 2 hardware serial(googling, somebody said it does not have 2 serial). So, I changed to ESP32 NodeMCU.

Before I posted here, I could check serial monitor something broken.

So, I have checked the setting and find some weird. why is the result in serial monitor different?

Firmware : 0.4

Below code is just modified.

MyxaESC myxa(&Serial2, 115200, &Serial, 115200,MYXA_STATUS_CMD_HOLDUP_MS,MYXA_RUN_TASK_HOLDUP_MS);

NodeMCU + Myxa(microUSB connect)

13456×2234 970 KB
NodeMCU + Myxa(DC-Power/14v)

23456×2234 954 KB
NodeMCU + Myxa(DC-Power/14v) + BLDC motor(not running) :

3_13456×2234 1.37 MB

3_23456×2234 1.84 MB

denny · July 24, 2022, 2:56pm

is there way to downgrad the firmware from 4.0 to 3.0??

pavel-kirienko · July 24, 2022, 3:31pm

Yes. Older firmware revisions are still available upon mere request, but we no longer distribute them publicly. Your request is unusual, however, because normally, there should be no reason to downgrade. Could you please clarify what you are trying to achieve? If you require any older firmware version, please either PM me or send a message to support@zubax.com.

mah · July 25, 2022, 6:46am

Can you post some photos of your setup?

denny · July 25, 2022, 12:20pm

For firmware 4.0, something changed.
I check the byte order comparing to kajuwise’s code.

byte controlModeBytes[4] = {myxaUnescapedMsg[97], myxaUnescapedMsg[98], myxaUnescapedMsg[99], myxaUnescapedMsg[100]};

above line should be chaged like this.

byte controlModeBytes[4] = {myxaUnescapedMsg[101], myxaUnescapedMsg[102], myxaUnescapedMsg[103], myxaUnescapedMsg[104]};

mah : your code is difficult to me. So I couldn’t modify. However, very thannks!!!