It is supposed to communicate with stm32 and uart.
When data comes into rx (to ble), app_uart_get is used, but an error occurs once when data is transmitted in it, so the data does not come in properly.
1. stm32 uart setting
=> flow control disabled, 1 stop bit, none parity bit
2. ble uart setting
=> rx: 2, tx:28 (nrf52833)
3. When stm32 sends data to uart, data loaded in tx buffer
4. Data received by ble through uart rx
5. data loss and uart comm error
-> 
-> 
In the middle stage, it seems that there is no problem with the uart itself, seeing that 0xfa comes after 0xfe, but when it is put into another buffer again, a communication error occurs and data loss occurs.
When 0xfe is entered in rx_buffer for the first time, the p_buf value of m_rx_fifo is also updated to 0xfe.
When the next value, 0xfa, was entered, the value of m_rx_fifo was not updated, and a uart comm error occurred. When the next value, 0x40, was entered, the p_buf value was updated again.
I'm not sure why this is.
uart_event_handler
