> Simple home-made driver for the SX1276 and SX1262 LoRa chip

Beware of what nailed the Meshtastic people: These chips don't have temperature dependent crystal oscillators. Transmitting more than a few milliseconds causing a temperature rise, throwing the clock off, causing transmission warpage, causing timing errors, causing transmission failures.

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ShakataGaNai 3 days ago | parent | next [-]

Temperature Compensated Crystal Oscillators (TCXOs) is what they should be looking for. And to be clear you can get SX1262 variants with such, eg: https://wiki.seeedstudio.com/wio_sx1262/

For the detailed run down, see https://cdn.sparkfun.com/assets/f/f/b/4/2/SX1262_AN-Recommen... page 14

> In the case of an SX1262 operating at +22 dBm in the US 902 – 928 MHz band, the frequency drift measured during the maximum LoRAWAN™ packet duration stays below the maximum limit, provided thermal insulation is implemented around the crystal during PCB design.

> At extreme temperatures (below -20 °C and above 70 °C), it is recommended to use a TCXO.

> For any other frequency bands corresponding to longer RF packet transmissions at +22 dBm, it is recommended to use a TCXO.

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buckle8017 3 days ago | parent [-]

Theory and reality are different here.

As used in the meshtastic devices this chip does actually fail doing normal Lora transmission under reasonable conditions.

I know because I've seen the exact failure.

	▲	nerdsniper 2 days ago \| parent [-]
		You've seen the failures in variants with a TCXO?

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Neywiny 3 days ago | parent | prev | next [-]

You mean they don't have temperature compensated? What you described is temperature dependent

	▲	exabrial 3 days ago \| parent [-]
		too late to edit now :)

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bigfatkitten 3 days ago | parent | prev | next [-]

This is a radio module issue, not a chip issue.

Cheap modules have cheap crystals, better ones have a TCXO.

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oakwhiz 3 days ago | parent | prev [-]

The chip itself supports using a TCXO instead of a regular crystal