How to receive LoRa packets with sync_word other than lorawan public(0x34) and lorawan private(0x12)

[ask-gh]

Hi,

I've been looking into extending the board to handle configurations outside of the loRaWAN protocol. I'm assuming here that the hardware is capable of capturing this data?

I'm using:

• rpi 4b
• seed studio wm1302 concentrator
• seed studio wm1302 pihat

From the docs it wasn't clear whether the sync word is configurable from the configuration files - from the looks of the source code it is not. I narrowed it down to this function

sx1302_hal/libloragw/src/loragw_sx1302.c

Line 1111 in 4b42025

int sx1302_lora_syncword(bool public, uint8_t lora_service_sf) {

What value would be required in the second parameter of lgw_reg_w() here? It seems from the other sync words that, for sync word 0x {val1} {val2}

RX_TOP_FRAME_SYNCH0_SF7TO12_PEAK1_POS_SF -> 2 * {val1}
RX_TOP_FRAME_SYNCH0_SF7TO12_PEAK1_POS_SF -> 2 * {val2}

This may be a complete coincidence, hence the question.

On top of this, I would also want the option to set a custom preamble length. From the source code it appears that this would need to be set in sx1302_lora_modem_configure:

sx1302_hal/libloragw/src/loragw_sx1302.c

Line 971 in 4b42025

err |= lgw_reg_w(SX1302_REG_RX_TOP_TXRX_CFG6_PREAMBLE_SYMB_NB, 10); /* LSB */

A couple questions,

• Why has the value be set to 10 to cover the SF5/6 preamble length of 12 and SF7-12 length of 8 for lorawan?
• Is this the correct place to be changing the length if I want it to be, say, 16?

Thanks in advance :)