uart 57600 Packet loss

Question

I use the softdevice which is s130.The code is from the demo: 
 static void nus_data_handler(ble_nus_t * p_nus, uint8_t * p_data, uint16_t length)
{
 for (uint32_t i = 0; i < length; i++)
 {
 while(app_uart_put(p_data[i]) != NRF_SUCCESS);
 }
// while(app_uart_put('
') != NRF_SUCCESS);
}
 
 When I use the uart (which baudrate is 57600) to transmit the mass data from BLE ,i find that i always loss some bytes in an packet. 
 I think we have the while() in the code to make sure the packet cannot be lost.So we cannot find this situlation.But it is not. 
 Can you tell me why???

Stefan Birnir Sverrisson · Accepted Answer

Hi Davy 
 When UART data is lost, it is usually either because UART TX buffer is too small or because the BAUD rate is too slow. I suspect the former in your case. Make sure you use app_uart_fifo.c instead of app_uart.c in your project. Try also to make the UART fifo TX buffer larger, defined with UART_TX_BUF_SIZE constant in the ble_app_uart example in the SDK.