Sending a NULL character in BLE UART example

RE: Sending a NULL character in BLE UART example

aaron.mcneil — Thu, 01 Apr 2021 13:23:39 GMT

That ia a good thought. I am using the exact same receive method as I do when I send a different type of message with a different character on the end but I will explore this.

RE: Sending a NULL character in BLE UART example

awneil — Thu, 01 Apr 2021 13:18:56 GMT

[quote userid="99624" url="~/f/nordic-q-a/73465/sending-a-null-character-in-ble-uart-example/302852#302852"]the null character is not being sent[/quote]

how do you know it's not being sent ?

maybe the problem is at the receiving end ... ?

RE: Sending a NULL character in BLE UART example

aaron.mcneil — Thu, 01 Apr 2021 13:02:07 GMT

I am using the ble_app_uart example.

In the uart_event_handle, uart_app_get is called each time a character is received from the uart and data_array is filled with each character so it can be sent out over BLE. Index is also incremented each time a character is received. When it is time to send out the message over BLE, ble_nus_send_data is called and data_array and index are passed to it. I verified that data_array has the elements I expect in it including the null character at the end. Index is also the correct length. However, the null character is not being sent. If I send a similar message with a different character at the end, it is sent correctly.

RE: Sending a NULL character in BLE UART example

awneil — Wed, 31 Mar 2021 15:52:01 GMT

The Nordic UART Service (NUS) can certainly send arbitrary binary data - all byte values from 0x00 to 0xFF

Are you using one of the SDK examples?

They assume that the UART is connected to a terminal, with a person typing manually at that terminal - so are probably filtering out "non-printing" characters.

Remember, also, that NUL is the string terminator in C - so you won't be able to use any standard C str...() functions.