RAK811 - Unable to set SF6

lmreglmuk · September 28, 2020, 3:22pm

Issue: I seem to be unable to set SF6 on a RAK811. It returns an Error 2 (argument not found). The hardware supports it, the documentation for the RAK811 suggests it is supported both through AT commands and the API however it always returns an error.

Setup: I am using a WisNode RAK811 Development board, version V3.0.0.13.H.T3.

Details: I successfully change to LoRaP2P mode and can set the SF to any other value [7-12] and have tried all combinations of BW and CR in case there is any restrictions on certain configurations. The command I am using is at+set_config=lorap2p:868100000:6:1:1:5:10.

Can anyone confirm if they have been successful in configuring SF6 and if so how? Does anyone know what the problem might be?

Many thanks.

@nmcc

nmcc · September 28, 2020, 6:19pm

Certainly could work as per documentation but this may need a new firmware build as.

The SX1276 SF6 support requires a non-generic register setup that wouldn’t take the normal range of parameters so is likely to need to be added.

And the RUI LoRa config code has validation to check for SF from 7 to 12:

github.com

RAKWireless/Products_practice_based_on_RUI_v2.0/blob/be2f71abf3b263abe07edd5ec1dbdb99c3b9fafa/based on RAK811/RAK811/lora_config.c#L1538


        return FAIL;
}
else
{
    if(verify_param_len(argv[0], 10) == FAIL)
        return FAIL;
}


/* Spreadfact: 7-12 */
if((atoi(argv[1])>12)||(atoi(argv[1])<7))
{
    RUI_LOG_PRINTF("ERROR: %d\r\n",RUI_AT_PARAMETER_INVALID);
    return FAIL ;
} else Spreadfact = atoi(argv[1]);

if (Spreadfact < 10)
{
    if(verify_param_len(argv[1], 1) == FAIL)
        return FAIL;
}

@Nicholas & @anon55548400 can you advise if this can be implemented or will it require a STM32 build from scratch?

@lmreglmuk, can you give us some context to the SF6 requirement - is it speed of transmission, maximising bandwidth, reducing potential RF interference?

anon55548400 · September 28, 2020, 8:49pm

Hey @nmcc,

As you mentioned, the SF = 6 is a particular use case for the highest data rate transmission possible with a LoRa modem. To support it, several settings must be applied in the SX1276/77/78/79 registers when it is in use. Due to the error pointed, I can say that the team probably did not consider the SF6 option during development.

@Fomi can provide your opinions about this issue?

Cheers,
Maria H.

Fomi · September 29, 2020, 1:36am

Hi, @anon55548400 @nmcc @lmreglmuk

Yes, the default setting for LoRaWAN stack is only SF0 ~ SF5, as @anon55548400 mentioned, we haven’t considered the SF6 option during development.

@lmreglmuk, can you please tell us why you want to use SF6? Sorry for that, but we need some information to evaluate whether we should support SF6 in the next version firmware.

Thank you!

frank_r · September 3, 2021, 8:32pm

I’m having problems with SF6 also. In P2P mode. Looking at the Current and RAK811 UART responses, the transmission times is about 10ms for a BW125KHz and 8ms preamble 60 bytes, CR1. The Semtech tool indicates I should be getting about 64ms transmission time. Definitely the radio chip in RAK811 is not programmed correctly.

carlrowan · September 5, 2021, 1:54am

Regarding SF6, there was no support with RAK811. If really necessary, you need a different FW with RAK811. You can check STM32Duino via Lmic if SF6 is supported.

Another option is use a newer module like RAK3172 that uses the STM32WL LoRa SoC that supports SF6.

frank_r · September 5, 2021, 4:36am

NOPE! That’s not true at all. At least be honest with me sir!. It says right there in RAK811 AT document SF6-12. Why lie to me? Do your documents mean anything?

beegee · September 5, 2021, 6:21am

@frank_r
Thank you for finding a mistake in our documentation.
Documents can have mistakes and we are permanently improving them…
Can you give me the link to the document you found SF6 please. We will correct this mistake.