Ble connection distance adjustment

[siltvm]

Hi,

Currently, I am developing a project using the nRF52810 as my controller. I am using an emulated project of ble_app_uart with the SoftDevice S112. I have integrated the timer peripheral into the project to perform LED indications based on some Bluetooth commands received from the APK. I am using the Nordic UART service to send responses back to the APK. However, I observed that after a successful Bluetooth connection, when the distance between the controller and the APK increases beyond a few meters, it disconnects. I have a question: Is there any way to increase the Bluetooth connection distance between the controller and the APK?

IDE: SEGGER Embedded Studio version 5.42a
SDK: nRF5 SDK 17.0.2

[Sigurd]

Hi!

Are you using a custom board or the DK?

[siltvm]

Hi,

During the firmware development stage, we used the nRF52832 PCA10040 development board. Currently, we are using a custom PCB with the nRF52810 controller.

I just read somewhere that adjusting the transmission power range can improve signal strength, thereby increasing the bluetooth range. Is this possible?

[Sigurd]

Hi!

For custom boards, it's also important to tune the antenna, have a good PCB layout, etc to get good range.

siltvm said:

I just read somewhere that adjusting the transmission power range can improve signal strength, thereby increasing the bluetooth range. Is this possible?

Yes, correct, use the function sd_ble_gap_tx_power_set() for that. You can set it to +4 dBm when using the nRF52823 and nRF52810.

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s112.api.v7.2.0/group___b_l_e___g_a_p___f_u_n_c_t_i_o_n_s.html?cp=5_7_0_2_2_1_3_31#gad10e80ba20ddab42d1753fd1be2d8c26

[siltvm]

hi,Sigurd ,

I created a function to adjust the transmission power. The function definition is given below. I called the function before the advertising start function call and flashed the code into the PCA10040 nRF52832 development board. I believe it's rebooting. What could be the possible issues?

When I adjust the transmission power of BLE_GAP_TX_POWER_ROLE_ADV, there's no problem. However, adjusting the power of BLE_GAP_TX_POWER_ROLE_CONN causes the issue

void tx_power_modification()
{

int8_t tx_power = 4;  // Value can range from -40 to +4 dBm

uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, 0, tx_power);
printf("BLE_GAP_TX_POWER_ROLE_ADV : %d\n",err_code);
APP_ERROR_CHECK(err_code);

uint32_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_CONN, 0, tx_power);
printf("BLE_GAP_TX_POWER_ROLE_CONN: %u\n", err_code);
APP_ERROR_CHECK(err_code);

}

[Sigurd]

siltvm said:

However, adjusting the power of BLE_GAP_TX_POWER_ROLE_CONN causes the issue

Since you are not in a connection yet, then sd_ble_gap_tx_power_set() likely returned BLE_ERROR_INVALID_CONN_HANDLE

[siltvm]

hi Sigurd , modified the code according to your suggestion. adjusted the power of BLE_GAP_TX_POWER_ROLE_ADV before starting advertising and BLE_GAP_TX_POWER_ROLE_CONN after establishing the Bluetooth connection. observed a slight variation in advertising and connection distance over a few meters (3 to 4).  tested this behavior on a development board. Are there any other options for improving the connection range? What is the maximum BLE connection and advertising range for the nRF52810?

[Sigurd]

siltvm said:

What is the maximum BLE connection and advertising range for the nRF52810?

It depends on the PCB/board, and the RF environment the device is in.

siltvm said:

Are there any other options for improving the connection range?

Again, it's important to tune the matching network/antenna and have a good PCB layout to get good range. This is maybe the most important thing.

siltvm said:

observed a slight variation in advertising and connection distance over a few meters (3 to 4).

For connections, if only 1 side of the link have increased TX-power, then it might not make that much difference in range, if the device that increased the TX-power is also the device with the poorest RX sensitivity.

If you want, you can create a new private case, ask for a PCB layout review of your board. We can also help with the tuning.

 General PCB design guidelines for nRF52 series