Lowest power mode on rak3172 using interrupt + timers

LPWAN Modules / EVBs RAK3172
1

Hi,

I’m starting to use RAK3172 module for a battery powered application and this consumes ~7.7uA, far from the ~1,7uA claimed.

I’m using 2 GPIO pins with interrupts for external events and up to 3 timers (RAK_TIMER_0,1,2). GPIOs go to push buttons so doesn’t consume until pressed.

At setup end I have: api.system.lpm.set(1);
And in the loop: api.system.scheduler.task.destroy();

I have made some tests in order to lower the consumption with no success. I have removed the timers and the exact I have the same exact consumption.

Can anybody please guide me in how to reduce this figure? I’m using only the RUI3 api.

Thank you
Antonio

2

Welcome to the forum @AntonioPWNT

(1) 1.7uA is the MCU in low power mode, no application running, I never got a RAK3172 with a custom application down to that value
(2) Do the two GPIO’s for the interrupts have pull-ups or pull-down resistors? If yes, how many Ohm are the resistors.

3

Thankyou for your answer!

I’m using 3 GPIO with a push button

two have 10M resistor to GND
one have 10M resistor to VCC

just configured these PINs as INPUT (pinMode(GPIOxx, INPUT)).

Best regards
Antonio

4

That will not cause the additional 6uA you see.
I am guessing it is from the LoRa antenna RF switch + some other pull-ups/pull-downs that are inside the RAK3172 .

5

Agree.

I have just changed the pinMode INPUT to INPUT_PULLUP/PULLDOWN acordingly and saved an additional 0,5uA.

6

I was going to try and help but for some reason I cannot find the SX1262.c or SX126x.c files for RAK3172, only the headers? Is it opensource, where can I find it?

Anyways, for RAK11720 and RAK4630 (and I am assuming on the RAK3172) there was an issue and I had mentioned it to support. Basically here is what is happening: SX126xAntSwOn() and SX126xAntSwOff() functions are not being used. I changed my local build of RAK11720 so I am more efficient, I saw a 6uA current draw drop when the RADIO_ANT_SW is correctly toggled using the SX126xAntSwOn() and SX126xAntSwOff() functions.

2 Likes
7

Hi @beegee ,

can you please check what @brolly759 says?

Thank you
Antonio

8

ALready in our ToDo list. No ETA given.

2 Likes
9

I assume you have modified the mentioned SX1262.c files, right? And not simply called “SX126xANTSwOn or Off” in your code? I guess you’d need to have those c-files at hand to compile successfully.

10

This instructions are for the RAK11720:

In sx126x-board.c file the functions should be as follows:

void SX126xAntSwOn( void )
{
udrv_gpio_init(RADIO_ANT_SW, GPIO_DIR_OUT, GPIO_PULL_NONE, GPIO_LOGIC_HIGH);
}

void SX126xAntSwOff( void )
{
udrv_gpio_init(RADIO_ANT_SW, GPIO_DIR_OUT, GPIO_PULL_NONE, GPIO_LOGIC_LOW);
}

in that same file the SX126xWakeup function should be like this:

void SX126xWakeup( void )
{
    //CRITICAL_SECTION_BEGIN( );
    SX126xAntSwOn();
    GpioWrite( &SX126x.Spi.Nss, 0 );

    SpiInOut( &SX126x.Spi, RADIO_GET_STATUS );
    SpiInOut( &SX126x.Spi, 0x00 );

    GpioWrite( &SX126x.Spi.Nss, 1 );

    // Wait for chip to be ready.
    SX126xWaitOnBusy( );

    // Update operating mode context variable
    SX126xSetOperatingMode( MODE_STDBY_RC );

    //CRITICAL_SECTION_END( );
}

In sx126x.c

void SX126xCheckDeviceReady( void )
{
    if( ( SX126xGetOperatingMode( ) == MODE_SLEEP ) || ( SX126xGetOperatingMode( ) == MODE_RX_DC ) )
    {
        SX126xWakeup( );

        SX126xAntSwOn( );
    }
    SX126xWaitOnBusy( );
}

In sx126x.c as well:

void SX126xSetSleep( SleepParams_t sleepConfig )
{
    SX126xAntSwOff( );

    uint8_t value = ( ( ( uint8_t )sleepConfig.Fields.WarmStart << 2 ) |
                      ( ( uint8_t )sleepConfig.Fields.Reset << 1 ) |
                      ( ( uint8_t )sleepConfig.Fields.WakeUpRTC ) );
    SX126xWriteCommand( RADIO_SET_SLEEP, &value, 1 );
    SX126xSetOperatingMode( MODE_SLEEP );
}
11

I mentioned this bug to the team in May of this year, so who knows when it will get fixed. I dont know why, but I thought all the files are open source for the latest RUI3 versions? If we can get @beegee to tell us how to access the files: sx126x-board.c and sx126x.c files for RAK3172, then we should be good to do it ourselves. The above instructions might also fix the issue on RUI3 with RAK4630 as well.

12

A quick search in the mounted BSP folder of the RAK4630 shows that they are in the variants folder:

image
image939×598 31.8 KB

For the RAK3172 it is different, the functions are part of the STM32 core (because the LoRa transceiver is inside the STM32WLE5).

I found the sx126x.h, but there is no sx126x.c file. It might be in the SUBGHZ stuff which I can’t find.