RAK 5205 tracker

End Devices (Nodes)
98

Schematic for the 5205:
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:slight_smile:

1 Like
99

Thanks.

With no connection to the GPSs Vbkp pin, if you want to use hot fixing you can only use software shutdown of the GPS and that only reduces current to 500uA. Maybe the schematic is in error here.

There is a power switch to turn off the power to the GPS, which would reduce its sleep current to 0. However turn the power on and the GPS is starting from cold, with a typical run time of 40 plus seconds at 33mA, very battery unfriendly.

100

I can confirm that V_BCKP (pin 6) is not connected (measured with multimeter) to VCC_3V3 (nor GPS_3V3, nor VBATT nor VBIN) .
One would expect it to be connected to VCC_3V3 (which is battery powered). I also do not see a solder jumper that could enable it.
With some soldering craftmanship V_BCKP may be manually connected to VCC_3V3. According to the datasheet that would draw 15 uA (@3.0V) backup current for the MAX-7Q.

The power for the GPS can be switched off completely (with PA15), so if correctly switched off the GPS should not contribute to the measured 1.5mA in ‘low power’ / sleep.

101

15uA would be about right for a Ublox in software shutdown, but I was going on the GITHUB for the RAK 5206 which says they are using a L76. This matches the schematic.

If they swapped to a Ublox MAX 7Q, then they ought not to have left Vbckp floating, from the 7Q datasheet;

“If no backup supply voltage is available, connect the V_BCKP pin to VCC_IO (or to VCC if not avaiable)”

102

I have a RAK5205 VER.B board here with a Ublox MAX-7Q.

103

The GPS switch off with PA15 is flawed because it does not disconnect the RX line input to the GPS. This means the RX line will be powering the GPS via the GPS module input protection circuitry. You can work around this HW limitation by disabling the serial port in software putting the pin in input mode.

1 Like
104

new firmware for RAK5205 Wistrio, V3.0.0.2

105

Anyone tested sleep current on the new fw?

1 Like
106

image

3 Likes
107

new firmware for RAK5205 Wistrio, V3.0.0.3

108

My RAK5205 won’t do anything with this new firmware. Am I missing something?
I have a WisTrio-Lora RAK5205 rev B.

Regards,
Andre

109

Sorry for bothering… Solved.

110

cool… what did you ‘missed’ ?

111

Reading the updated manual… Tried to upload “old” way…
Missed the need for updating de BOOT section :slight_smile: