Init与c库open()的串行通信导致TX在RPi上发送一个位

I'm trying to set up a serial communication between the RPI and an FPGA. However, there is an issue when using the standard C library open() to init the serial interface: I'm using a scope to monitor what is sent and received via the RX and TX lines. A call to open causes the TX line of the RPI to go low for the length of one bit. I do not see this behavior with other computers/linux PCs. The point is, the FPGA assumes a valid transmission, since he thinks it's a start bit, but it's not. I'm trying to set up a serial communication bet