increase transmission buffer size in ble_app_uart_c transfer large data

[Autobot]

hello,

I need send 10000bytes large data send central to peripheral in single transmission. I using example code ble_app_uart_c in SDK15.2 nrf52832. what are the parameter i change to increase transmission buffer size in central and peripheral code...???? 

[Amanda Hsieh]

Hi, 

You can edit UART_TX_BUF_SIZE/ UART_RX_BUF_SIZE in main.c. You can change this define to increase or decrease the number as per your requirement but keeping the RAM size in mind. Please also see this post.

#define UART_TX_BUF_SIZE        256                                     /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE        256                                     /**< UART RX buffer size. */

Best regards,

Amanda

[Autobot]

Thanks for replay Amanda Hsieh,

I testing send central to peripheral 10000bytes in every 5seconds using below function

for(;;)
{
err_code=ble_nus_c_string_send(&m_ble_nus_c, send_Data, sizeof(send_Data)); //send_Data size like 10000byte

APP_ERROR_CHECK(err_code);
nrf_delay_ms(5000);
}

error code return this kind of error

 0> <warning> ble_nus_c: Connection handle invalid.

In my application I can transmit 10000bytes central(ble_app_uart_c) to peripheral(ble_app_uart) SDK15.2.

How did Connection  handle transmit 10000bytes send to peripheral any handle function is there...???

[Amanda Hsieh]

No, that won't work.

You need to split the data because ble_nus_c_string_send does not handle 10000 bytes.

Take a look on how it's done in uart_event_handle() in ble_app_uart_c:

if ((data_array[index - 1] == '\n') || (index >= (m_ble_nus_max_data_len)))

 

If the string/data being sent have a \n character or if m_ble_nus_max_data_len is reached, the data will be sent. 

m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - OPCODE_LENGTH - HANDLE_LENGTH; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */

 

-Amanda

[Autobot]

m_ble_nus_max_data_len is 244bytes i split by 244bytes and send every transmission first transmission successful receive peripheral but balance data doesn't send properly central show error 

 0> <warning> ble_nus_c: Connection handle invalid.

 0> <warning> ble_nus_c: Connection handle invalid.

 0> <warning> ble_nus_c: Connection handle invalid.

 0> <warning> ble_nus_c: Connection handle invalid.

in every transmission how to handle connection valid to transfer peripheral

for(;;)
{
	for(uint16_t cnt=0;cnt<10000;cnt++)
			{
				send[len]=data[cnt];
				len++;
				if(len>=244)
				{
				err_code=ble_nus_c_string_send(&m_ble_nus_c,send, sizeof(send));//send size 244byte
				if(err_code != NRF_ERROR_INVALID_STATE && err_code != BLE_ERROR_INVALID_CONN_HANDLE)
					{
							APP_ERROR_CHECK(err_code);
					}
					len=0;
				}
			}
	}

[Jørgen Holmefjord]

I will continue the support in your other thread about this issue.