PC Serial Port
Information on the PC Serial Port
Serial Frame
Serial Frame Format
The table below shows some serial frame specs for different baud rates.
| Baud | Bit Width | Frame Width (1 start bit, 8 data bits) |
Real Data Rate * (1 start bit, 8 data bits, no parity, 1 stop bit) |
|---|---|---|---|
| 4800 | 208.33us | 1875us | 480 Bytes/s 0.47 KBytes/s |
| 9600 | 104.17us | 937.5us | 960 Bytes/s 0.94 KBytes/s |
| 19200 | 52.08us | 468.75us | 1920 Bytes/s 1.88 KBytes/s |
| 38400 | 26.04us | 234.38us | 3840 Bytes/s 3.75 KBytes/s |
| 57600 | 17.36us | 156.25us | 5760 Bytes/s 5.63 KBytes/s |
| 115200 | 8.68us | 78.13us | 11520 Bytes/s 11.25 KBytes/s |
* It takes a minimum of 10 bits (1 start bit, 8 data bits,
no parity, 1 stop bit) to transfer 8 bits of real data. Real data rate is equal
to 1/(bitwidth * 10), or Baud/10.
Linux Serial Port Setup
stty is a command line tool for setting up the serial port. Below are some examples of use.
Set Baud to 9600, use one stop bits.
> stty -F /dev/ttyS0 9600 -cstopb
Set Baud to 115200, use two stop bits.
> stty -F /dev/ttyS0 115200 cstopb
Set Baud to 115200 and character size to 5 bits (can be 5 to 8). Enable parity, set to odd parity.
> stty -F /dev/ttyS0 115200 cs5 parenb parodd
Set Baud to 115200 and character size to 8 bits. Enable parity, set to even parity.
> stty -F /dev/ttyS0 115200 cs8 parenb -parodd
