i want to do simple data transfer and why blueetooth serial terminal was not be able to detect the device?

[venkatesha kj]

how to do simple data transfer using bluetooth serail terminal?

[Karl Ylvisaker]

venkatesha kj said:

i have set the transmit power to 4dbm but in nrf connect app rssi level was -45dbm when i am near to the device will the tx power set to 4dbm or not?

No, the +4 dBm is what the radio will be outputting - so the RSSI on the receiving device will always be lower than the power it was sent with. -45 dBm is a normal value for a close device.

venkatesha kj said:

and am using s140 can i set Supported tx_power values: -40dBm, -20dBm, -16dBm, -12dBm, -8dBm, -4dBm, 0dBm, +3dBm and +4dBm.
* In addition, on some chips following values are supported: +2dBm, +5dBm, +6dBm, +7dBm and +8dBm. any of the tx power level?

The possible TXPOWER levels depends on which SoC you are using, not which SoftDevice you are using. You could see which power levels are supported in the TXPOWER register of the device you are working with.

Best regards,
Karl

[venkatesha kj]

RSSI actually indicates the received strength right then if the transmited signal strength is 4dbm then why rssi shows -45dbm?

[Karl Ylvisaker]

The RSSI is the received signal strength indicator. The signal will always be received weaker than what it was transferred as on the other side of the link.

Best regards,
Karl

[venkatesha kj]

err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, tx_power_level);

if tx power set to 4dbm it increases the transmission range right?

[Karl Ylvisaker]

Yes, compared to +0dBm it will increase the transmission range.