CC254X transmission speed test

i want to test the transmission speed between two CC2541 development boards.

Based on function simpleBLECentral.c that TI provided, I made some modification as follow. I want to send data from Central to Peripheral.

But I found that only the first attempt was successful. char1 read from peripheral is 65, that is 'A'. All the other attempts are failed. I have changed connection interval, from 4*1.25ms, 10*1.25ms, 100*1.25ms to 1000*1.25ms. I want to ask the reason why it failed in the later attempt. where should I change? If you can provide the test code or test result, it will be the best

我想用CC2541两块开发板之间测试蓝牙的传输速率。

在TI提供的simpleBLECentral.c函数中，做了如下修改。即在主从机建立连接之后，通过拨动五向开关往上拨，让主机去发送字节给从机。

每次看LCD屏上的信息，都说我只写成功一次，从机char1中的数据为65，即‘A’。之后的写入全部都失败。我也修改过connection interval，采用过4*1.25ms，10*1.25ms，100*1.25ms，1000*1.25ms这几个值，最多只能写入成功一次，有时候一次都不成功，我想请问是因为什么，造成了这个原因？我应该修改哪里，才可以完成我的测试？

else if ( simpleBLEState == BLE_STATE_CONNECTED &&
          simpleBLECharHdl != 0 &&
          simpleBLEProcedureInProgress == FALSE )
{
  uint8 status;
  uint16 sta_times=0;
  
  // Do a read or write as long as no other read or write is in progress
  if ( simpleBLEDoWrite )
  {
      int i,j;
      attWriteReq_t req;

 
      req.handle = simpleBLECharHdl;
      req.len = 1;
      req.sig = 0;
      req.cmd = 0;
      for(j = 0; j<20; j++)
      {
        req.value[0] = 'A'+j;
        i=0;
        do{
           status = GATT_WriteCharValue( simpleBLEConnHandle, &req, simpleBLETaskId ); 
           i++;
           if(i>10)
               break;
           if(status == SUCCESS)
               sta_times++;
        }while(status != SUCCESS);
      }
      LCD_WRITE_STRING_VALUE( "****", req.value[0], 10, HAL_LCD_LINE_4 );
    
    
    system_time = osal_GetSystemClock();
    key_time = system_time - key_time;
    LCD_WRITE_STRING_VALUE( "**aa**", key_time, 10, HAL_LCD_LINE_5 );
    LCD_WRITE_STRING_VALUE( "**aa**", system_time, 10, HAL_LCD_LINE_6 );
    LCD_WRITE_STRING_VALUE( "sta_times", sta_times, 10, HAL_LCD_LINE_7 );
    key_time = system_time;
  }
  else
  {
    // Do a read
    attReadReq_t req;
    
    req.handle = simpleBLECharHdl;
    status = GATT_ReadCharValue( simpleBLEConnHandle, &req, simpleBLETaskId );
  }
  
  if ( status == SUCCESS )
  {
    simpleBLEProcedureInProgress = TRUE;
    simpleBLEDoWrite = !simpleBLEDoWrite;
  }
}