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krish j
krish j
Associate II
September 15, 2017
Question

Low output power LORA STM32L073 nucleo board

  • September 15, 2017
  • 5 replies
  • 2207 views
Posted on September 15, 2017 at 16:29

Hi All,

I am using STM32l073 nucleo board with module. I am unable to get power more than 14.6 dBm while transmitting data packet. On my other device i am able to get 19 dbm of power using same sx1272 module.

I tried writing the PADAC and PACONFIG registers separately as well still my power is not going above 14.6 dBm.

Any help would be greatly appreciated

Thanks

#nucleo-l073rz #lora #sx1272
This topic has been closed for replies.

5 replies

Tesla DeLorean
Tesla DeLorean
Guru
September 15, 2017
Posted on September 15, 2017 at 17:24

Are these 'modules' of the same design? What's the tolerance of the parts in the RF path?

Can't fix hardware issues with more software..

Your description doesn't have the details I need to see if we're talking about an apples-to-apples comparison.

Custom modules, data sheets, images, links to...

This?

http://www.st.com/en/evaluation-tools/p-nucleo-lrwan1.html

 
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krish j
krish jAuthor
Associate II
September 18, 2017
Posted on September 18, 2017 at 13:02

Hi,

I am using P-NUCLEO-LRWAN1 for Indian ISM band (ISM_865), As per Indian ISM band maximum radiated power is 30dBm but i am not getting  more than 14dBm.

Software Details: en.i-cube_lrwan (downloaded from Stmicroeletronics site)  

Define Indian Region (REGION_IN865) in preprocessor directive 

I know Sx1272 is  capable to radiate till 20dBm only.

Question:  Is there any setting to get more than 14 dBm output, any hardware dependency or power (5 v , 12 v)?

I am using USB port for power

Any help would be greatly appreciated

Thanks

Tesla DeLorean
Tesla DeLorean
Guru
September 18, 2017
Posted on September 18, 2017 at 15:22

 ,

 ,

Measuring at the output or via software settings?

♯ define TX_OUTPUT_POWER , , , , , , , , , , , , , , , , , , , , , , , , , , , , 20 , , , , , , , // dBm (14 - 25mW, 20 - 100mW)

Not aware of any supply side issues, USB should be able to supply sufficient current for 100mW operation. You could try a 2.1A type USB charger supply.

Have you reviewed the schematic for the shield?

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Tesla DeLorean
Tesla DeLorean
Guru
December 7, 2017
Posted on December 07, 2017 at 16:57

Must also adjust the current limit settings in SX1272

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krish j
krish jAuthor
Associate II
September 19, 2017
Posted on September 19, 2017 at 09:28

I tried changing this but had the same result. I also tried to writing into the PACONFIG register directly which provides the 20db boost but to no avail. 

krish j
krish jAuthor
Associate II
September 20, 2017
Posted on September 20, 2017 at 09:44

I tried changing   

#define  TX_OUTPUT_POWER          20        // dBm (14 - 25mW, 20 - 100mW)  on

en.i-cube_lrwan ping_pong project Indian ISM band 

but had the same result ,Measuring at the output on Spectrum analyzer getting 14dbm still now. 

this is my 

en.i-cube_lrwan End_node project min ,max and default powers.

/*!

* Minimal Tx output power that can be used by the node

*/

#define IN865_MIN_TX_POWER TX_POWER_10

/*!

* Maximal Tx output power that can be used by the node

*/

#define IN865_MAX_TX_POWER TX_POWER_0

/*!

* Default Tx output power used by the node

*/

#define IN865_DEFAULT_TX_POWER TX_POWER_0

/*!

* Default Max EIRP

*/

#define IN865_DEFAULT_MAX_EIRP 30.0f

/*!

* Default antenna gain

*/

#define IN865_DEFAULT_ANTENNA_GAIN 2.15f

any idea how to get max tx_power of 20dbm please guide me.

Tesla DeLorean
Tesla DeLorean
Guru
September 21, 2017
Posted on September 21, 2017 at 02:35

Have you tried a 915 MHz signal?

Have you checked the current limiter settings?

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Andrew Neil
Andrew Neil
Super User
December 7, 2017
Posted on December 08, 2017 at 00:35

By default, the LoRaWAN EndNode example has Adaptive Data Rate (ADR) defined - you need to turn that off.

See my earlier question: 

https://community.st.com/0D50X00009XkbSMSAZ

 

As far as I can find, there is no proper API to specify the output power.

:(

EDIT

Just to say that I was only looking to reduce output power - didn't investigate how to increase it!

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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