Dear community,

I'm working on sx1280 with home made board ( STM32 + SX1280 over SPI).
The first basic uses case was to make a ping-pong over two board.

It's work, but the range is not conforme as expected ( RF communication fault over 45m).
In spide of the RF setting was set to +13db Tx power, the effective RF power measured by spectrum analyser directly on component RF pin ( without Z adaptation), give me +2db.

this following picture show my measure in function of RF settings.


my question, is anyone here have already use this IC ? measure is RF Power ? a mistake on my reasoning ?
thanks in advance.

 

Too many variables to give you a straight answer.

When you were measuring RF power what mode was the transmitter in and what were you transmitting? Was your antenna matching connected at the time? What is your spectrum analyser and how were you connecting it?

 

Too many variables to give you a straight answer.

When you were measuring RF power what mode was the transmitter in and what were you transmitting? Was your antenna matching connected at the time? What is your spectrum analyser and how were you connecting it?

Right, more details :
-> Freq : 2.4Ghz @ GFSK
-> Mode SetContinousWave
-> No Zadapation. The RF output is "around 40r" (from datasheet), analiser RF input "50r".
not the correct adaptation, but not enought for loose +10dBm...
-> Connected directly on RFIOby a SMA pigtail.
-> Analyser reference 'Rohde & Swchwarz FSL6'

 

And your normal antenna matching was completely disconnected? What is the PCB layout for your RF connection?

 

First i have try to measure directly on IC RFIO pin.
In spide of the Z impedance adaption was not correct, the value must be near the goal.
in second time, i have do the same measure WITH the Z adaption preconised by constructor.

same problem...
as my custom board without RF IC, but connected to the official devboard do the same problem, i think that the problem come from firmware.
BUT, after run an example with a arduino board +official devboard + web arduino lib do the same...
i'm lost

 

Hard to see how it could be firmware. One thing you could try is measuring IDD at each RF power point as per table 3-8 and confirm they are in the right ballpark...

 

the problem is solved !

The cause : RF cable quality AND a RF attenuator (value not correct) .
I have discover that by replacing my device with a signal generator with exactl the same path.

Now i'have the correct rf power.

thanks for your help, yours idea.


SOLVED