LR1121 Custom PCB without SKY13588-460LF

[gc9n]

Hi there , i use a LR1121 , and in my design i do not use SKY13588-460LF Switch , as an MCU i use STM32L4

I can talk to LR1121 , i can update the Radio firmware , i can send all commands , however , the RSSI is stuck on -127, i assume that In order to Set LR1121 in MODE_RX DIO5 have to be HIGH DIO6 have to be Low , DIO5 and DIO6 is handled by SKY13588...

any help?

[jgromes]

I can't really offer any guidance on the particular RF switch you have selected. It is possible the -127 value is caused by some problem in the library. However, to help you further, I will need the information requested by the issue template, mainly the code you are running and all output from the serial console.

[gc9n]

Hi again , and i am sorry i double checked with the Evaluations Board of LR1121 SEMTECH
and With My design , and i found the issue. my Design ignores this command ,

lr11xx_status_t lr11xx_radio_set_rx_with_timeout_in_rtc_step( const void* context, const uint32_t timeout )
{
    lr11xx_status_t status                                  = LR11XX_STATUS_ERROR;
    const uint8_t   cbuffer[LR11XX_RADIO_SET_RX_CMD_LENGTH] = {
        ( uint8_t ) ( LR11XX_RADIO_SET_RX_OC >> 8 ),
        ( uint8_t ) ( LR11XX_RADIO_SET_RX_OC >> 0 ),
        ( uint8_t ) ( timeout >> 16 ),
        ( uint8_t ) ( timeout >> 8 ),
        ( uint8_t ) ( timeout >> 0 ),

    };

or if you prefer better this

int16_t LR11x0::setRx(uint32_t timeout) {
  uint8_t buff[3] = {
    (uint8_t)((timeout >> 16) & 0xFF), (uint8_t)((timeout >> 8) & 0xFF), (uint8_t)(timeout & 0xFF),
  };
  return(this->SPIcommand(RADIOLIB_LR11X0_CMD_SET_RX, true, buff, sizeof(buff)));
}

i have the exact behavior in Semtech board when i dont set the LR1121 to RX mode. which is dead RSSI ,i change channels etc but the RSSI is dead. is -127. its not in RX mode , its on the default state i guess standby

i want to confirm if its a HArdware issue

[jgromes]

Can you post the code you are running, as I have asked in my previous post? I'm guessing you are calling LR11x0::getRSSI, but since you have not posted your code, I cannot be sure.

I also invite you to examine the RadioLib documentation for LR11x0::getRSSI:

    /*!
      \brief Gets RSSI (Recorded Signal Strength Indicator) of the last received packet. Only available for LoRa or GFSK modem.
      \returns RSSI of the last received packet in dBm.
    */
    float getRSSI() override;

The comment clearly says "of the last received packet". If you have yet to receive a packet, then I don't know what will the result be.

[jgromes]

Closed due to inactivity.