Seeeduino Lorawan gps Power Consumption higher than expected...

Products & Technology Arduino & Seeeduino
#1

Hello,



I’m having problems with the seeeduino LoRaWAN +gps board. The rated current in sleep mode is 80uA. However, following the steps of the wiki, I cannot achieve nothing near that value of consumption.



Removing all the leds and testing the board with the suggested sketch for low consumption it draws 17-18mA powered at 3.5V though the battery connector.



Reading the GPS module datasheet it says that it has a current consumption is 12mA when tracking (and I think the gps is tracking by default) so that could be the problem… There is an “stand by mode” you can enter by sending the command: $PMTK161,0*28



But even doing so the current doesn’t drop much… Also the seeedstudio wiki does not say anything about that…



This is the sketch I am using:

[code]#include <LoRaWan.h>
#include <EnergySaving.h>

EnergySaving nrgSave;

void blink()
{
for(unsigned char i = 0; i < 5; i ++)
{
digitalWrite(13,HIGH);
delay(500);
digitalWrite(13,LOW);
delay(500);
}
}

void setup()
{
Serial.begin(9600); // gps

for(unsigned char i = 0; i < 26; i ++)      // important, set all pins to HIGH to save power
{
    pinMode(i, OUTPUT);
    digitalWrite(i, HIGH);
}

lora.init();
blink();    
lora.setDeviceLowPower();
blink();   

Serial.write("$PMTK161,0*28\r\n");

nrgSave.begin(WAKE_EXT_INTERRUPT, 7, dummy);    // buton on D7 to wake up the board
nrgSave.standby();

}

void loop()
{
blink();
nrgSave.standby();
}

void dummy(void)
{
// do something
}

// END File[/code]

Any help will be appreciated.

#2

Hello there,

I’m having exactly the same problem but I managed to get it down to ~320uA. The GPS needs to be carefully handled as it wakes up directly when nudging any of the power lines.

Have you reached the stated 80uA in any way?

#3

I have followed this example code code erasing everything but the bare minimal comparing it to my code and it only gets me down to ~320uA and it isn’t close to the stated 80uA.

They even state in the example below that a rating of 60uA is possible with the following code.

I’m using a firmware of 3.x

#4

I have found out that at least 200uA of the current comes from the GPS module being in standby-mode and not the lowest consumption backup-mode.

Entering backup mode with a current of about ~2uA is not possible because the input VCC is hardwired to the module. So it is a dead case where you need to remove the gps module if you want to be able to draw less current

#5

Could you tell me the SKU of the gps module?

#6

Not really. It’s a part of 102010128.

Conclusion for my sake to get to the 80uA is that you need to remove the gps or modify the board so that it follows the specification for entering the v_backup-mode.

you can probably get even lower by adjusting peripherals in the mcu also.