RFM69HW Power Measurements

[gussabina]

Hello All:

I was testing the auto-power feature the way it is implemented by RFM69_ATC.cpp library but I was not able to fully regulate the power down to the minimum. Taking a closer look at the library I see the setPowerLevel( ) is only using the PA1+PA2+High-Power mode, and it doesn't use other lower power modes.
So I decided to test all different modes and measure the current in each one, and I found the attachment table.
I didn't populate all RSSI but values missing values are between those in the table. The idea was to configure the radio in all possible power levels and measure the corresponding current.
All configurations in Output Power that appear in the table are the ones really affect the current. All configurations between those values measured the same level of current, so no point on using them.

In my case, for maximum power configuration (PA1+PA2+High-Power mode), no matter the value of Output Power (31..16), the current was always the same ~47.86mA.

I would like to hear if someone experimented similar results.

Thanks
Gus

[perky]

Some similar experiments done here:
https://andrehessling.de/2015/02/07/figuring-out-the-power-level-settings-of-hoperfs-rfm69-hwhcw-modules/

Mark.

[TomWS]

Hello All:

I was testing the auto-power feature the way it is implemented by RFM69_ATC.cpp library but I was not able to fully regulate the power down to the minimum. Taking a closer look at the library I see the setPowerLevel( ) is only using the PA1+PA2+High-Power mode, and it doesn't use other lower power modes.
So I decided to test all different modes and measure the current in each one, and I found the attachment table.
I didn't populate all RSSI but values missing values are between those in the table. The idea was to configure the radio in all possible power levels and measure the corresponding current.
All configurations in Output Power that appear in the table are the ones really affect the current. All configurations between those values measured the same level of current, so no point on using them.

In my case, for maximum power configuration (PA1+PA2+High-Power mode), no matter the value of Output Power (31..16), the current was always the same ~47.86mA.

I would like to hear if someone experimented similar results.

Thanks
Gus

Did you disable AGC on your RSSI sniffer during the test?  (See LNA register settings) I don't remember if RSSI takes the gain factor into consideration.

Tom

[gussabina]

Now I'm thinking I have a current limitation from the power supply, and for this reason max current is ~47mA and not 130mA as datasheet states.

I will change power supply and run again.

Thanks
Gus

[gussabina]

Hello TomWS:

No, but I will check it. Thanks.

Regarding the RSSI, I modified the point in which the readRSSI() is call because it worked better for me (comparing RSSI between Gateway (my hardware) and Sniffer (Moteino)).
In the Moteino library, the call is at the end of the interruptHandler() while in mine it's at the beginning. In fact, in the Moteino library this function appears at the begining also, but it's commented out. So it seems it was there previously.

Thanks
Gus