Set the transmit power on NRF51822

[Rashmi]

Hi

We are using BL600-SA in our project. I need to configure NRF51822 transmit power so that it is discoverable at particular distance.

I am using softdevice S110 and I tried to set the Tx power using sd_ble_gap_tx_power_set() function, but I did not finding any difference 

in the RSSI value. The API is returning NRF_SUCCESS. I have also tested with softdevice S130, but that is also not working us.

Can anyone please suggest me the way to configure the transmit power level?

Regards,

Rashmi

[Rashmi]

Hi Simonr,

I didn't test example with SDK 12.3. Will do it on Monday. If the issue with hardware, then in the other board it should have worked as the module was powered for first time and also flashed for the first time.

The RSSI is exact same and there is no much difference. 

nRF5x_MDK_8_2_0_IAR.msi was in the SDK10 folder when we downloaded from the Nordic website. We will try to install the latest version of MDK file and let you know the result after testing.

Thanks,

Rashmi.

[Simonr]

Hi Rashmi

I also tested the example in SDK10 with S110, and I am able to see an increase in RSSI when testing as I did with SDK12.3 and SoftDevice S110. Approximately the same difference between 4 and -8 dBm where I can see the signal going from ~50dB to ~40dB. Are you sure you're changing the "#define TX_POWER_LEVEL                      (4)" in your main.c function? And are you sure that you build the project before flashing it to the chip?

Note: I used the Keil µvision 5 IDE to compile and flash this program, so there might be some issues with IAR for the SDK 10 (I'm not sure about this though, as the SDK is rather old, and I'm not too familiar with IAR).

Best regards,

Simon

[Rashmi]

Hi Simonr

We have tested the ble_app_proximity  example in SDK 12.3. We are not finding any difference in the RSSI value(with -8 and 4dBm Tx power level). We have also tested the example code with two different modules, but the results are same. 

Thanks,

Rashmi

[Simonr]

Hi Rashmi

Okay, then it might be that the signal strength won't get any higher than it already is at the close range. How much is the RSSI value at any of the TX power levels? You can try moving the peripheral further and further away from the central, as you should see the RSSI drop faster (at a lower range) at a lower TX power. 

Best regards,

Simon

[Rashmi]

Hi Simonr,

We are getting the RSSI value of -95dBm at any of the Tx power levels. If we place central and peripheral very closer i.e less than 2cm, we are able to get the RSSI value of -76dBm.

Thanks,

Rashmi