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

[Simonr]

Hi Rashmi

As per the BL600-SA datasheet, the typical receive sensitivity is at -91dBm (which could easily be -95 in an office environment). At what range does the chip stop advertising altogether with the different TX powers, I don't think you'll be able to see any differences up close with the antenna that is on the BL-600.

Best regards,

Simon

[Rashmi]

Hi Simon

We are able to get the maximum of -100dBm for all the Tx power levels at the distance of 30cm. If we increase the distance we are not able to detect the Bluetooth device.

Thanks,

Rashmi

[Simonr]

Hi Rashmi

That seems very strange. Do you use the antenna on the module itself or have you built a custom board around it? Is the device in some sort of casing or similar? This does not seem like a problem with the TX power to me, but rather a hardware issue. If you want, I can set this case to private mode and take a look at your schematics and PCB layout (if this is a custom board, that is).

Best regards,

Simon

[Rashmi]

Hi Simon

We have contacted the LAIRD to check if there is any hardware issue with the module. They suggested us to set PO.20 LOW(0) to get 4dBm normal Tx power. Set PO.20 HIGH(VCC) to get Tx whisper mode power(-30dBm to -55 dBm).

In our application we have set the pin PO.20 to low and now we are getting the range approximate 12 meters inside office environment. Seems like they have some hardware configuration to allow the module to transmit at higher power when PO.20 made low.

Thanks for your support.

Thanks,

Rashmi

[Simonr]

Hi

Thank you for your update, I was not aware of this, sorry about that. Glad you were able to figure it out!

Best regards,

Simon