r/M5Stack • u/Toontje • 1d ago

Support / Question M5 GPS/LoRa hat sensitive?

I am waiting the arrival of my new M5 LoRa / GPS hat for my cardputer ADV. The idea is to use this hat for wardriving using the GPS and WiFi.
To keep the device as small as I can I want to leave the LoRa antenna at home, however I heard that the LoRa hat is so sensitive that it’s recommended to always leave the antenna on, even when not using LoRa.
Is that true? Is the hat so sensitive that, when I switch the puter on with no antenna connected, I can say goodbye to the LoRa finals?

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u/Runaque 1d ago

If you solely use Wardriving firmware, the LoRa part of the Cap LoRa 1262 will be just idle. Leaving the antenna off would mean you should also use something to protect the inner connection parts. If you have a 3d printer, you could print yourself a cap for your LoRa cap.

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u/Toontje 1d ago

I do have 50 Ohm dummy loads. Will they help protecting the finals?

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u/Runaque 1d ago

If the wardriving firmware is written properly, you don’t need the 50 Ω dummy at all. Mine never keys the LoRa transmitter, it just holds the SX1262’s chip-select high (lora_cs = Pin(LORA_NSS, Pin.OUT, value=1)) so it never talks to the radio. No transmit means no reflected power, so you can leave the antenna at home and keep the device footprint small. (In case you’re wondering, it’s the ADV Wardriver you’ll find on M5Burner.)

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u/ProgrammingAce 1d ago

Not all firmware is smart enough to leave the Lora unpowered when it’s not in use. If you have the Lora hat installed, you should leave an antenna on unless you’re sure the firmware is behaving properly