RAK4270 - RXD Glitch causes wake up

LPWAN Nodes
1

Hello

We are power profiling our new LoRa Sensor based on RAK4270 and have found the resulting problem

  1. Put RAK4270 to Sleep

  2. Put HOST CPU to Sleep. All I/O Lines Tristate / Disabled. TXD to RAK4270 low (not driven)

  3. The HOST CPU wakes up and at this point the TXD goes high

  4. This causes the RAK4270 to exit sleep and therefore waste power.

I have tried a large pullup (150K) on the RXD Line and this causes the RAK4270 to draw more power in sleep mode.

I cannot find documentation stating that the RAK wakes up on a rising edge of the RXD line !

Comments Please

Thank You

2

Hi Paul,

It is in the AT Command documentation Appendix IV. I will update the docs and add these notes on the sleep command so that it can’t be missed out.

image
image887×204 26.6 KB

3

Hi Carl
Thank You for your reply

Are you able to enquire when the new firmware for the RAK4270 will be available ?

We need this information so we can inform our clients when we can ship

Thank You

KR
Paul

4

Paul, that’s not a firmware update, it’s making what you discovered more obvious in the docs.

You could put some sort of MOSFET switch in the line controlled by the MCU.

Or you could, for this iteration, live with the wasted power - I see that idle mode isn’t documented - I’d guess at 5mA - and you could send a sleep command immediately if the MCU doesn’t need to use the module.

5

Sorry Nick

My error in a poor response.

The question regarding firmware was added because beegee mentioned in another post about there being a new firmware and I wanted to ask Carl if he knew of any dates

KR

Paul

6

Ah, so, not the thread you were looking for :wink:

I’m not even sure @carlrowan & @beegee are in the same city/town so it may be that @carlrowan isn’t in the loop on that one!

7

Hi @dingoxx ,

I asked the FW team about the target release. But for now I don’t have the official words from them yet. Hopefully I get the info tomorrow and I will update you ASAP.