AS923 Class C not working?

[Harald]

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:

pycom.rgbled(0x141400)
	# 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
	lsock.setblocking(False)
	
	#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.settimeout(10)
	lsock.setsockopt( socket.SOL_LORA, socket.SO_CONFIRMED, 0 )
	print('waiting for data')
	while(True):
		try:
			data, port = lsock.recvfrom(128)
			proto_handler_multi(data, port)
		except TimeoutError:
			send(bytes([0x01,0x00]))
			#print('still waiting...')
			continue

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?

[Harald]

@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
print('Joining...')
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():
    time.sleep(2.5)
    print('Not joined yet...')

print('Joined')

# remove all the non-default channels
print('Removing other channels')
for i in range(1, 16):
    lora.remove_channel(i)

# 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
s.setblocking(False)

time.sleep(5.0)

pkt = b'PKT #' + bytes([i])
print('Sending:', pkt)
s.send(pkt)
time.sleep(4)

print('Listening...')
while True:
    rx, port = s.recvfrom(256)
    if rx:
        print('Received: {}, on port: {}'.format(rx, port))
    time.sleep(1)

[Harald]

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

[oligauc]

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

[Harald]

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

[bmarkus]

@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.

[jcaron]

@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?

[Harald]

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?

[oligauc]

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