The packet transmission interval is incorrect

Question

SDK： nRF5_SDK_11.0.0 Softdevice： s132_nrf52_2.0.0_softdevice
project：\examples\ble_peripheral\ble_app_uart\pca10040\s132\arm4\ble_app_uart_s132_pca10040.uvproj

II would like to use nRF52832 get the maximum throughput, I set the minimum connection interval to 50ms, the following is my modified part of the code:

#define MIN_CONN_INTERVAL               MSEC_TO_UNITS(50, UNIT_1_25_MS)             /**< Minimum acceptable connection interval (50 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL               MSEC_TO_UNITS(50, UNIT_1_25_MS)             /**< Maximum acceptable connection interval (50 ms), Connection interval uses 1.25 ms units. */

typedef struct  blk_send_msg_tag

{
	
    uint32_t start;      //发送的起始地址
	uint32_t max_len;    //待发送数据总长度
	uint8_t  *pdata;
}blk_send_msg;

blk_send_msg g_send_msg;  
uint8_t g_data[500];

uint32_t ble_send_data(uint8_t *pdata, uint32_t len)

{

	if (NULL == pdata || len <= 0){ return NRF_ERROR_INVALID_PARAM;}

	uint8_t temp_len;
	uint32_t err_code;
	g_send_msg.start = 0;
	g_send_msg.max_len = len;
	g_send_msg.pdata = pdata;

	temp_len = len>20 ? 20 : len;
	err_code = ble_nus_string_send(&m_nus, pdata, temp_len);
	if (NRF_SUCCESS == err_code)
	{
		g_send_msg.start += temp_len;  
	}
	return err_code;
}

uint32_t ble_send_more_data()

{

	uint32_t err_code;
	uint32_t dif_value;

	dif_value = g_send_msg.max_len - g_send_msg.start;
	if (0 == dif_value || NULL == g_send_msg.pdata)
	{ 
		return NRF_SUCCESS; 
	}

	uint8_t temp_len;
	temp_len = dif_value>20 ? 20 : dif_value;
	err_code = ble_nus_string_send(&m_nus,g_send_msg.pdata + g_send_msg.start, temp_len);
	if (NRF_SUCCESS == err_code)
	{
		g_send_msg.start += temp_len;
	}
	return err_code;
}

Add BLE_EVT_TX_COMPLETE to on_ble_evt():  
    case BLE_EVT_TX_COMPLETE: 
            printf("\r\nBLE_EVT_TX_COMPLETE\r"); 
            ble_send_more_data();  
            break;  

And then send the data：
    ble_send_data(g_data, 500);

Through the serial port found every 100ms received a BLE_EVT_TX_COMPLETE

The following figure is my capturing packet data：

image description

Why not 50ms received a packet, if I want a connection incident to send 6 packets how to operate?

Hung Bui · Accepted Answer

You need to make sure you sent the request for connection parameters update. (check that in the sniffer trace) 
 When you receive BLE_EVT_TX_COMPLETE, you should call ble_nus_string_send() as much as possible until you receive NRF_ERROR_RESOURCES. Then you start again when you receive BLE_EVT_TX_COMPLETE