Peripheral UART example show echo text, how to fix it?

[William.SportsArt]

Hi support team,

My environment:
nRF52-DK / PCA10040 / s132   (central)   by   \nRF5_SDK_17.1.0_ddde560\examples\ble_central\ble_app_uart_c
MDBT42Q-DB   (peripheral)   by   \nRF5_SDK_17.1.0_ddde560\examples\ble_peripheral\ble_app_uart
SDK 17.1.0
MDK IDE-Version: V5.38.0.0

COM4 is peripheral, COM5 is central, why does com4 always echo the same text but com5 doesn't?
How to fix the echo text problem?

[Jørgen Holmefjord]

Hi,

Are you using the examples from the SDK without any modifications?

Have you tried switching which board runs which firmware, to see if the behavior follows the FW or the board?

I'm not familiar with this serial terminal software, but some softwares have a feature to local echo text, is this enabled in one of the terminals but not the other?

Best regards,
Jørgen

[William.SportsArt]

Hi Jorgen,

Thank you for your reply.

I'm using examples from the SDK without any modifications.

I tried switching central & peripheral firmware to both development boards, and the echo text issue was also switched.

Thus, the echo text issue happens in the peripheral firmware.

How does peripheral firmware have this issue? How to fix it?

Thank you.

[hmolesworth]

Ain't the peripheral, it be central .. check this setting; central has an option to echo everything received over BLE from the peripheral back to the peripheral over BLE just as though someone sent a new command:

on Central:
    if (ECHOBACK_BLE_UART_DATA)
    {
        // Send data back to the peripheral.
        do
        {
            ret_val = ble_nus_c_string_send(&m_ble_nus_c, p_data, data_len);

[William.SportsArt]

Hi,

Thank you for your reply.

You are right, the echo text was from Central.

I disabled ECHOBACK_BLE_UART_DATA and tested again, the result is as follows. (Figure 1)

Thank you.

[hmolesworth]

You're welcome, thanks for letting me know it helped; trick is to enable the same feature on the peripheral and they will happily chat for hours :-)