AS923 Class C not working?

  • I ran into a problem trying to use class C on AS923.

    Class A works like expected, but when I change to class C, I cannot receive anything. The joining procedure works fine.

    This is my declaration:

    global lora
    lora = LoRa(mode=LoRa.LORAWAN, power_mode=LoRa.ALWAYS_ON, region=LoRa.AS923, device_class=LoRa.CLASS_C)

    socket and Hello message:

    	# create a LoRa socket
    	global lsock
    	lsock = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
    	lsock.setsockopt( socket.SOL_LORA, socket.SO_DR, 2 ) # datarate
    	#send Hello packet
    	print('sending Hello')
    	lsock.setsockopt(socket.SOL_LORA, socket.SO_CONFIRMED, 1 )
    	model = 0
    	if 'model' in settings.dic:
    		model = settings.dic['model']
    	send( bytes([ CMD_HI , 3, settings.PROTO_VERSION, settings.SW_VERSION, model ]) )

    This is how I wait for a message:

    	lsock.setsockopt( socket.SOL_LORA, socket.SO_CONFIRMED, 0 )
    	print('waiting for data')
    			data, port = lsock.recvfrom(128)
    			proto_handler_multi(data, port)
    		except TimeoutError:
    			#print('still waiting...')

    The gateway (a CloudGate) receives the message and sends messages when I want to but I don't see anything happening on the LoPy. Anyone ran into this issue before?

  • @oligauc

    Can you tell what is wrong with this code then:

    from network import LoRa
    import socket
    import binascii
    import settings
    import sys
    import time
    import pycom
    LORA_FREQUENCY = 923000000
    LORA_FREQ_ADD =  20000
    LORA_GW_DR = "SF10BW125" 
    LORA_NODE_DR = 2
    # initialize LoRa in LORAWAN mode.
    # Please pick the region that matches where you are using the device:
    # Asia = LoRa.AS923
    # Australia = LoRa.AU915
    # Europe = LoRa.EU868
    # United States = LoRa.US915
    lora = LoRa(mode=LoRa.LORAWAN, region=LoRa.AS923, device_class=LoRa.CLASS_C)
    # create an OTA authentication params
    dev_eui = binascii.unhexlify('70b3d5499da97f9c')
    app_eui = binascii.unhexlify('ADA4DAE3AC12676B')
    app_key = binascii.unhexlify('11B0282A189B75B0B4D2D8C7FA38548B')
    # set the 3 default channels to the same frequency (must be before sending the OTAA join request)
    print('Adding channels')
    lora.add_channel(0, frequency=923200000, dr_min=0, dr_max=5)
    #join a network using OTAA
    lora.join(activation=LoRa.OTAA, auth=(dev_eui, app_eui, app_key), timeout=0, dr=LORA_NODE_DR)
    #lora.join(activation=LoRa.OTAA, auth=(dev_eui, app_eui, app_key), timeout=0)
    # wait until the module has joined the network
    while not lora.has_joined():
        print('Not joined yet...')
    # remove all the non-default channels
    print('Removing other channels')
    for i in range(1, 16):
    # create a LoRa socket
    s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
    # set the LoRaWAN data rate
    s.setsockopt(socket.SOL_LORA, socket.SO_DR, LORA_NODE_DR)
    #test set unconfirmed.
    s.setsockopt(socket.SOL_LORA, socket.SO_CONFIRMED, 0)
    # make the socket blocking
    pkt = b'PKT #' + bytes([i])
    print('Sending:', pkt)
    while True:
        rx, port = s.recvfrom(256)
        if rx:
            print('Received: {}, on port: {}'.format(rx, port))

  • The files have been sent! Thanks for looking into this! I will update this thread once the code is fully functional.

  • Global Moderator

    @harald. Please can you send your complete code to support ( ? Class C in the AS923 region works. Please see the pic below:
    0_1539936066796_AS923 Class C.png

  • @jcaron
    I'm using OTAA and can see the joining works like it should.

  • @jcaron said in AS923 Class C not working?:

    I have to admit I don't even know how channel/data rate selection works for class C downlinks... I suppose there must be default channels, and some MAC commands to change that?

    Channel plan is the same for Class A and Class C devices, difference is how downlink delivered. Class A devices listen continously on RX2 channel after RX1 window closed followed by uplink, so you can send downlink any time. Class C is also used for Multicast but as far as I know it is not implemented by PyCom.

  • @harald You may want to check the region-related files in the source code to see if there's anything obvisouly different on the topic for AS923.

    I have to admit I don't even know how channel/data rate selection works for class C downlinks... I suppose there must be default channels, and some MAC commands to change that?

    What type of join are you using? OTAA or ABP?

  • I am Using a CloudGate and create the packets on the gateway itself. I can see the packets being sent, but nothing received on the LoPy. When I changed to EU HW and changed my code to EU868, it worked normally.

    When I send from the LoPy to the gateway, I also see the packets of my LoPy.
    Also Class A functions normally. It looks like it's not listening in Class C when using AS923. How can I confirm this?

  • Global Moderator

    What lorawan server are you using ? You can see downlink packets on your lora gateway ?


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