linux serial communication protocol driver

#Linux serial communication protocol driver drivers#

Spin_unlock_irqrestore(&tty->buf.lock, flags) Tty->buf.tail->commit = tty->buf.tail->used Spin_lock_irqsave(&tty->buf.lock, flags) It will set the low_latency flag, which is used y the kernel when moving data up in the tty layer : void tty_flip_buffer_push(struct tty_struct *tty) It will also confirm that if it is or not a fifo threshold problem.ġ0 msec 115200 is enough to transmit 100 bytes (assuming 8N1), so what you are seeing is probably because the low_latency flag is not set.

#Linux serial communication protocol driver drivers#

Other specialized drivers and user programs work through it.

libusb is the core library of routines that handle the USB 2.0 Protocols in Linux. Also available in the Linux kernel source is a serial driver for devices that use the FTDI USB interface chips. On a PC, you can go hardcore and talk to standard serial ports directly, issue setserial /dev/ttySx uart none to unbind linux driver from serial port hw and control the port via inb/outb to port registers. Linux Communication with FT2232C-based USB Devices. Try if stty -F /dev/ttySx raw lowlatency helps, no guarantees though. However, having the ARM handle a 10 kHz interrupt rate will certainly not be good for the overall system performance.Īnother options is to pad your packet so that you hit the fifo threshold every time. Serial ports on linux are 'wrapped' into unix-style terminal constructs, which hits you with 1 tick lag, i.e. If you are lucky, you can tweak the driver behaviour without patching, but you still need to look at the driver code. Now if you want to stick with your protocol and reduce latency, select, poll, read will all give you roughly the same latency, because as Andy Ross indicated, the real latency is in the hardware fifo handling. If you are interested in throughtput, look at windowed protocol, like kermit file sending protocol. Request / answer schemes tends to be inefficient, and it shows up quickly on serial port.