The CS (Susceptiblility) test is completed with UART output even if there is no response.

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

ovrebekk — Mon, 06 May 2024 09:24:15 GMT

Good to hear you figured out the cause of the problem, I will close the ticket then 🙂

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

pkr2258 — Thu, 25 Apr 2024 23:20:27 GMT

I'm sorry for the delay in registering your results.

In conclusion, there were no problems with nRF52.

A key-related element in the same PCB malfunctioned.

thank you.

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

Hung Bui — Thu, 15 Feb 2024 08:46:49 GMT

@SHMoon: What do you connect on the other side of the UART ?

Please do what I suggested to turn off app_uart_put() in ble_nus_chars_received_uart_print()
Please try to test and make sure you can do UART (without BLE) normally.

If you test with unmodified ble_app_uart do you see the problem ?

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

hmolesworth — Thu, 15 Feb 2024 00:15:51 GMT

Does the peripheral button have a pull-up enabled or an external pull-up? (Required)

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

SHMoon — Wed, 14 Feb 2024 23:56:35 GMT

I am using 4.7k pullups for tx/rx on nRF52832.

During the test, I added a pull-up to the other MCU, but it had no effect.

ECHOBACK_BLE_UART_DATA is disabled.

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

hmolesworth — Wed, 14 Feb 2024 23:37:57 GMT

Suggestion: turn on the internal pull-up on the Rx pin for both Central and Peripheral. With either Rx pin disconnected, without a pull-up the Rx inputs are both susceptible to generate noise such as this which will be forwarded to the Central via BLE and output on the UART.

Edit: Note you may have ECHOBACK_BLE_UART_DATA enabled, which further complicates testing

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

SHMoon — Wed, 14 Feb 2024 23:24:48 GMT

-nRF5_SDK_17.1.0

-NUS (Peripheral-Central)

We conducted an experiment dividing it into two cases.

Case 1) Peripheral power is turned off and central is scanning.

=> UART data above does not occur

Case 2) Peripheral is turned on and paired with central.

=> UART data above above occurs

[quote userid="2121" url="~/f/nordic-q-a/108254/the-cs-susceptiblility-test-is-completed-with-uart-output-even-if-there-is-no-response/468604"]Could you describe how the test is performed ?
The data output on UART were simply noise or it was some data ? [/quote]

There is absolutely nothing transmitted on the UART line that is simply noise.

The orange line below is the tx line of the nRF52832, and the white line is the rx line.

With tx data transmission, data is loaded on the rx line. In other words, the receiving side of communication is sending data through the rx line because the tx is normal.

In the waveform below, I haven't done any manipulation, but data is being generated when the button is pressed.

If you zoom in, it looks like that...

This statistic is actually how we use it.

(The transfer was made via static void ble_nus_chars_received_uart_print(uint8_t * p_data, uint16_t data_len)

Covers the basic format of the case. )

- start byte : 0x02

- mode : 0xA0 ( button )

- length : 0x02

- data : 0x1F (button )

-reserved : 0x00

- end byte : 0x03

Sometimes, tx is generated as shown below.

Occasionally, data that cannot be generated as shown below may be generated.

I didn't press any buttons,

I don't understand that the data of the communication protocol when the button is operated is transmitted through tx...

I checked the debugging messages with printf.

However, surprisingly, data was being sent to the tx line using the ble_nus_chars_received_uart_print function.

So the protocol was adjusted.

However, the only condition that enters this function is when the peripheral button is pressed, but no button is pressed at all.

I don't understand why it was implemented.

RE: The CS (Susceptiblility) test is completed with UART output even if there is no response.

Hung Bui — Tue, 13 Feb 2024 12:51:39 GMT

Hi SHMoon,

Could you describe how the test is performed ?
The data output on UART were simply noise or it was some data ?

If you turn off the line that output on UART: app_uart_put()

Do you still see the same problem ?