method to return if lora.nvram is available

[philwilkinson]

When a device has rebooted from a deepsleep, is there a simple method to check if lora.nvram_save() was implemented and can be used with lora.nvram_restore()?
line 3 in the sample code below is what I am trying to achieve, however calling lora.nvram_restore() does not return a value, so it cannot be used.
Any ideas?

from network import LoRa
lora = LoRa(mode=LoRa.LORAWAN)
if lora.nvram_restore(): #I want to do something like this
    lora.nvram_restore()
    while not lora.has_joined():
        time.sleep(0.5)
else:
    lora = LoRa(mode=LoRa.LORAWAN, region=LoRa.AU915, adr=False, tx_retries=0, device_class=LoRa.CLASS_A)
    appeui = binascii.unhexlify(app_eui)
    appkey = binascii.unhexlify(app_key)
    lora.join(activation=LoRa.OTAA, auth=(appeui, appkey), timeout=0)
s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
s.setsockopt(socket.SOL_LORA, socket.SO_DR, 5)
s.setblocking(True)
s.send("some data")
s.setblocking(False)
rev_data = s.recv(64)
print('recieved data: ', rev_data)
lora.nvram_save()
machine.deepsleep(some_time)

[Asb]

If you start by calling nvram_restore, you can check using lora.has_joined(), if lora.navram_save() was successfully saved, lora.has_joined() will return true

[philwilkinson]

@Asb thanks for the response.
As you can see from the code, I am using lora.has_joined() method. However lora.has_joined() takes some time to connect and return True, also the time it takes to connect is not predictable.
I hoped to call a method that immediately returned a Boolean to reduce time 'wasted' waiting to connect when nvram_save() was never used.

[philwilkinson]

OK @Asb comment got me thinking that everyone seems to be fine with the lora.has_joined() method call.
So I put a slight delay following the nvram_restore call, and it seems to work ok. 2 seconds seems to be optimal.
This code seems to work most of the time.

    lora = LoRa(mode=LoRa.LORAWAN)
    lora.nvram_restore():
    time.sleep(2)
    if not lora.has_joined():
        print('failed to join via nvram_restore')
        lora = LoRa(mode=LoRa.LORAWAN, region=LoRa.AU915, adr=False, tx_retries=0, device_class=LoRa.CLASS_A)
        for i in range(16, 65): #AU915 TTN gateways need channels removed
            lora.remove_channel(i)
        for i in range(66, 72):
            lora.remove_channel(i)
        appeui = binascii.unhexlify(app_eui)
        appkey = binascii.unhexlify(app_key)
        lora.join(activation=LoRa.OTAA, auth=(appeui, appkey), timeout=0)
        while not lora.has_joined():
            print('trying to join OTAA')
            time.sleep(0.5)
        print('connected and ready to publish')

    s = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
    s.setsockopt(socket.SOL_LORA, socket.SO_DR, 5)
    s.setblocking(True)
    s.send("some data")
    s.setblocking(False)
    rev_data = s.recv(64)
    print('recieved data: ', rev_data)
    lora.nvram_save()
    time.sleep(2)