E220 LoRa Receive-Intervall and MycroPython and Arduino Env communication (UnicodeError:)

[woto]

Hello,
I use the following to receive data:

while True:
    if lora.available() > 0:
       code, value = lora.receive_message()
       print(ResponseStatusCode.get_description(code))

       print(value)
       time.sleep(2)

My question is, what is the time.sleep(2) for?

I have noticed that if I send data within 2sec, then I get an error message in the Thonny IDE or the data is lost.

And what happens if several transmitters send data at the same time?

Kind regards,
woto

• This topic was modified 10 months ago by Renzo Mischianti.
• This topic was modified 9 months, 4 weeks ago by Renzo Mischianti.
• This topic was modified 9 months, 3 weeks ago by Renzo Mischianti.

[Renzo Mischianti]

Hi Woto,
if you don’t add the sleep time, the processor gets 100% of usage and can freeze.

If you receive more than one message, the messages are stored in the buffer of E220, and when you read them, you receive the two messages at once.

Bye Renzo

[woto]

Hi Renzo,

if the transmitter sends within 2sec, then the Micropython programme as receiver is terminated with the error unicode-error at line 636 in lora_e220.py.
What could be the reason for this? The message is only a few bytes long:
“Hello World! 1”. The next message is then “Hello World! 2” and so on.

best regards
Woto

[Renzo Mischianti]

Please, paste the complete error stack trace..
Bye Renzo

[woto]

Hi Renzo,
excuse me for the late answer.

I will do it today in the evening.

best regards,
woto

[woto]

Hi Renzo,
I have now found a little time to reproduce the error.

When I send a message every second I get the following message in the Thonny editor:

Traceback (most recent call last):
  File "<stdin>", line 127, in <module>
  File "/lib/LoraWanE220/lora_e220.py", line 636, in receive_message
UnicodeError: 

Maybe you can help me.

best regards
Woto

[Renzo Mischianti]

Hi Woto,
It seems that there is a character that’s not encoded correctly, which kind of message do you send?
Bye Renzo

[woto]

Hi Renzo,

I send with the following command:
e220ttl.sendFixedMessage(0, DESTINATION_ADDL, 18, DateTimeStr + " ,Hello, world?" + String (i));

The variable DateTimeStr is:

DateTime nowTime = MCP7940.now(); // get the current time
String DateTimeStr = String(nowTime.year()) + "." + String(nowTime.month()) + "." + String(nowTime.day()) + " " + String(nowTime.hour()) + ":" + String(nowTime.minute()) + ":" + String(nowTime.second());

OWN_ADDH = 0x00
OWN_ADDL = 0x01
i is an integer

If I send all 6s, everything is fine. Only if I send every second does this message appear and the programme stops.

[Renzo Mischianti]

But you send from Arduino env and receive in MicroPython env?
Bye Renzo

[woto]

Hi Renzo,
yes, that’s right.

best regards
Woto

[woto]

The sender is a ATTiny1616 and the receiver is a Rapsberry Pi pico.

• This reply was modified 10 months ago by woto.

[g0730n]

Do you have FEC on or off?

[woto]

Hi g0730n,
I do not know “FEC”. What does it mean?

[g0730n]

I’ve been experimenting some with data corruption on my setup sending between arduino and pi pico(micropython).

Factors to consider:

1. Timing
2. Forward Error Correction
3. “ReceiveMessageUntil()”, i have experimented with this setting as i was receiving two messages packed into one… eg. “Msg0Msg1”, using this setting seems to help??

If both devices are powered up at same time, and one LoRa begins receiving half way through the senders transmission, it will only receive half the message, hence corrupted data. I have only noticed this happening with FEC off, but more testing needed.

Once I’m able to log into forum here on my computer I will post my code for the working setup I’m putting together.

I am using bare ATMEGA328P chip on arduino side, and pi pico on the other side.

[woto]

ok, I read
https://mischianti.org/ebyte-lora-e32-micropython-exploring-library-2/
now.

I think it is on, because the Default-Value is ON.

[woto]

Hi g0730n,

thanks for answer.
I will test the function “ReceiveMessageUntil()”. Maybe it could help me.

[Renzo Mischianti]

I also pin this discussion, and if I find some time, I retrieve all devices and do some tests.
Give me feedback on your test.
Thanks, Renzo

[woto]

Hello,
I would now like to switch off the FEC in the Python programm.
How can I do this?

Thanks Woto

[woto]

Hello,
I now have data issued to me.
In lora_e220.py, I insert on line 636 (before data = data.decode(‘utf-8’):
print (data)

If I receive all 4s, I get the following output:
b’0212024.2.2 15:14:25 5cm’
After 4s the next output:
b’0212024.2.2 15:14:29 19cm’

If I receive every second, Data looks like this:
b’0212024.2.2 16:59:58 7cm\xf00212024.2.2 16:59:59 19cm’

After “7cm” it says \xf0. What does that mean?

• This reply was modified 9 months, 2 weeks ago by woto.
• This reply was modified 9 months, 2 weeks ago by woto.

[woto]

Hello,

When I enter the following in the Thonny IDE, I get an error message:

>>> b'\xf0'.decode()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeError: 
>>> 

I think the problem is the character \xf0.
This does not seem to be a Unicode character. Unfortunately, µPython does not allow you to specify a second parameter in the decode() function, e.g. data.decode('UTF-8','ignore').

This does not work.
But how can this be solved?

• This reply was modified 9 months, 2 weeks ago by woto.

[Renzo Mischianti]

Hi woto,
I must do some check, but someone uses this approach to clean the str

x.encode('utf-8','ignore').decode("utf-8")

But I must check It.
Bye Renzo

[woto]

Hi Renzo,
I tried it, but it does not work. I get the following error in der Thonny-IDE:

>>> b'0212024.2.2  15:26:34  3cm\xf60212024.2.2  15:26:35  22cm'.encode('utf-8','ignore').decode("utf-8")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'bytes' object has no attribute 'encode'
>>>

[woto]

Hi renzo,
I think I have a solution for myself, maybe for others too.
I have created a new static method in the class LoraE220:

@staticmethod
 def _cleanData(_data):
     data = bytes(_data)
        
     ret_values = []
     ret_arr = bytearray(ret_values)
        
     for i in range(len(_data)):
         if _data[i] <= 127 :
             ret_arr.append(_data[i])
     return ret_arr

This methode is called before the decode function:

str_ret = LoRaE220._cleanData(data)

data = str_ret.decode('utf-8')
msg = data

Now the decoding function works and if I define a separator for the sender, I can separate the messages from each other.

• This reply was modified 9 months, 2 weeks ago by woto.

[g0730n]

I will keep this in mind.

[Renzo Mischianti]

Hi Woto,
thanks. It’s very interesting and helpful.
I’m going to examine the situation, but with your help, I think It will become simpler.
Thanks again, Renzo.

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