nRF5340 Audio DK: LE Audio and UART2 Concurrently

Question

Hi, 
 I have problems with the nRF5340 Audio DK to get LE Audio and UART2 concurrently on the same CIS stream to work. 
 GOAL 
 Use 2 x nRF5340 Audio DKs to transfer audio both directions via Line IN and at the same time send UART2 data from and to the 2 kits concurrently. Exactly like the Walkie-Talkie demo but with LINE IN instead of Microphone. And the UART must be a physical one and UART2 was chosen with a UART/RS232 converter. So full duplex audio and serial data. 
 What I did so far 
 I did manage to modify the Application "<Path to ncs folder>\v2.2.0
rf\applications
rf5340_audio" to work with the LINE IN port. See my Forum post: nRF5340 Audio DK: Walkie Talkie Demo - LINE IN instead of MIC 
 I also managed to modify both these samples to work with UART2 instead of the CDC Com port UART0. I used the 2 Samples "Central UART" and "Peripheral UART". See my Forum post: 
 Central and Peripheral UART Samples on UART2 - nRF5340 Audio DK 
 Then I created a third Project with 2 applications that I want to combine the 2 projects. However, I only manage to get the "GATEWAY" paired with the NUS Server to work. But on the HEADSET side I can't get the NUS Client to work. I tested the combined GATEWAY and NUS Server (Peripheral UART) with a HEADSET only and with the NUS Client (Central UART). That is why I know the GATEWAY/NUS Server side works. 
 The Audio still works but I cannot receive or sent serial data on the NUS client side which is on the HEADSET application side. 
 Application 
 We need to transfer Audio and Data in a full duplex Intercom system over a short distance because the wiring of an audio and data line is not possible due to moving parts. 
 
 Could you please help me combine the 4 projects into 2 please? Is concurrent UART and LE Audio even possible? 
 
 Kind Regards

fweinrebe · Answer

Finally, it's working. :-) 
 The key to fixing this was to add the following line in gatt_discover() : 
 default_conn = conn; 
 This was why the UART (NUS) side complained about the connection. It was probably due to having to disable the call to " bt_enable() " during the setup of the UART (NUS). LE Audio is enabled before the NUS Client therefore LE Audio already makes a connection.

static void gatt_discover ( struct bt_conn * conn ) 
 { 
 int err ; 
 
 // This is the fix...Because bt_enable was disabled 
 default_conn = conn; 
 
 if ( conn != default_conn ) 
 { 
 return ; 
 } 
 
 err = bt_gatt_dm_start ( conn , 
 BT_UUID_NUS_SERVICE , 
 & discovery_cb , 
 & nus_client ); 
 if ( err ) 
 { 
 LOG_ERR ( " could not start the discovery procedure, error code: %d " , err ); 
 } 
 }

AND 
 
 In the NUS Client setup code disable the call to bt_enable():

// err = bt_enable(NULL); 
 // if (err) 
 // { 
 // LOG_ERR("Bluetooth init failed (err %d)", err); 
 // return; 
 // }

AND

I also moved the " bt_nus_client_send" related code into a separate thread procedure:

void ble_write_thread ( void ) 
 { 
 int err ; 
 
 printk ( "
 *** In ble_write_thread *** 
" ); 
 
 /* Don't go any further until BLE is initialized */ 
 k_sem_take ( & ble_init_ok , K_FOREVER ); 
 
 for (;;) 
 { 
 /* Wait indefinitely for data to be sent over Bluetooth */ 
 struct uart_data_t * buf = k_fifo_get ( & fifo_uart_rx_data , K_FOREVER ); 
 
 // Note: Problem here is that "nus_client->conn" does not 
 contain a valid connection. 
 // This is fixed by adding a line to procedure "gatt_discover". 
 
 err = bt_nus_client_send ( & nus_client , buf -> data , buf -> len ); 
 if ( err ) 
 { 
 printk ( " Failed to send data over BLE connection(err %d ) 
" , err ); 
 LOG_WRN ( " Failed to send data over BLE connection(err %d ) " , err ); 
 } 
 else 
 { 
 printk ( " Data sent data over BLE connection 
" ); 
 } 
 
 err = k_sem_take ( & nus_write_sem , NUS_WRITE_TIMEOUT ); 
 if ( err ) 
 { 
 printk ( " NUS send timeout 
" ); 
 LOG_WRN ( " NUS send timeout " ); 
 } 
 } 
 }

K_THREAD_DEFINE ( ble_write_thread_id , STACKSIZE , ble_write_thread , NULL , NULL , NULL , PRIORITY , 0 , 4000 );

Here is the main() loop:

void main ( void ) 
 { 
 // LE Audio 
 int ret ; 
 
 printk ( " InitLEAudio() 
" ); 
 InitLEAudio (); 
 
 // UART2 
 /* Don't go any further until LE Audio is initialized */ 
 k_sem_take ( & le_audio_ok , K_FOREVER ); 
 
 printk ( " InitUART2() 
" ); 
 InitUART2 (); 
 
 while ( 1 ) 
 { 
 // LE Audio 
 streamctrl_event_handler (); 
 STACK_USAGE_PRINT ( " main " , & z_main_thread ); 
 
 // UART2 
 /* Use seperate thread (ble_write_thread) for data to be sent over Bluetooth */ 
 } 
 }

k_sem_give ( & le_audio_ok ); was added to the end of void on_ble_core_ready ( void ) {...}

nRF5340 Audio DK: LE Audio and UART2 Concurrently

GOAL

What I did so far

Application

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