bt_nus_send() api returning negative value

RE: bt_nus_send() api returning negative value

Hung Bui — Mon, 07 Aug 2023 10:59:23 GMT

Hi,
Have you looked at my suggestion in the last reply ?
Please check which value returned. You receive "-ve" because you print "-ve" out.

send_through_uart("failed to send (returned -ve value)\r\n");

You need to print the actual error code out.

RE: bt_nus_send() api returning negative value

Theja — Mon, 07 Aug 2023 04:54:00 GMT

Hi Hung Bui,

I have tried to send data after sending first 20 bytes successfully but in the first 20 bytes only it's returning -ve value.

is there any suggestions?

RE: bt_nus_send() api returning negative value

Hung Bui — Thu, 03 Aug 2023 12:49:35 GMT

You can send as much as you want until you receive NRF_ERROR_RESOURCES. Then you can wait for BLE_GATTS_EVT_HVN_TX_COMPLETE event then you can continue.
Please look at the sd_ble_gatts_hvx() description:

RE: bt_nus_send() api returning negative value

Theja — Thu, 03 Aug 2023 07:09:09 GMT

But I'm sending 20bytes at a time, In "bt_nus_send(current_conn, data_to_be_transmitted, 20)" this API if i change "current_conn" to "NULL" that means all connected peers it's returning -128.

what I'm thinking is that, Is there any way like callback to monitor transmission is completed or not so that i can send next 20 bytes after transmission completed only.

here is the print regarding

03-08-2023 12:23:50.176 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:24:44.519 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:25:11.126 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:25:12.638 [RX] - CONNECTED<CR><LF>
failed=-128<CR><LF>

03-08-2023 12:25:13.698 [RX] - ACK not received<CR><LF>

03-08-2023 12:25:50.191 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:26:44.418 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:27:08.119 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:27:09.631 [RX] - CONNECTED<CR><LF>
failed=-128<CR><LF>

03-08-2023 12:27:10.693 [RX] - ACK not received<CR><LF>

03-08-2023 12:27:50.191 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:28:44.445 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:29:05.139 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:29:06.652 [RX] - CONNECTED<CR><LF>
failed=-128<CR><LF>

03-08-2023 12:29:07.712 [RX] - ACK not received<CR><LF>

03-08-2023 12:29:50.112 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:30:44.349 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:31:11.159 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:31:12.672 [RX] - CONNECTED<CR><LF>
ACK Received<CR><LF>

03-08-2023 12:31:50.142 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:32:44.458 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:33:08.158 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:33:09.670 [RX] - CONNECTED<CR><LF>
ACK Received<CR><LF>

03-08-2023 12:33:50.150 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:34:44.353 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:35:05.151 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:35:06.664 [RX] - CONNECTED<CR><LF>
ACK Received<CR><LF>

03-08-2023 12:35:50.145 [RX] - sensing_temperature<CR><LF>

03-08-2023 12:36:44.346 [RX] - sensing completed and stored in flash<CR><LF>

03-08-2023 12:37:11.057 [RX] - advertising for packet sending<CR><LF>

03-08-2023 12:37:12.569 [RX] - CONNECTED<CR><LF>
ACK Received<CR><LF>

03-08-2023 12:37:50.138 [RX] - sensing_temperature<CR><LF>

RE: bt_nus_send() api returning negative value

Hung Bui — Wed, 02 Aug 2023 13:01:23 GMT

If you have a look here:
you can find that error 122 is
#define EMSGSIZE 122 /**< Message size */

Most likely the payload you try to send is too large.
Please step inside bt_nus_send() and see what exactly throw the error.

Try to compare your code with what in the example to see why it didn't work.

RE: bt_nus_send() api returning negative value

Theja — Wed, 02 Aug 2023 12:57:12 GMT

Hi Hung Bui,

Thanks replying, I did that one also but I'm getting return value -122(unsuccessful) instead of 0(successful) from "bt_nus_send()" API.

RE: bt_nus_send() api returning negative value

Hung Bui — Wed, 02 Aug 2023 12:50:17 GMT

Hi Kumar,

Please printout the actual error value. Instead of printing this :
send_through_uart("failed to send (returned -ve value)\r\n");

You can print it out using:

send_through_uart("failed to send (returned : %d)\r\n",err_code);