BBB Mark/Space parity

Question

So I've enable UART-1 on the BBB. I've tried setting it up to use mark/space parity via termios & stty. According to the doc it supports this.

termios setup:

options.c_cflag &= ~CSTOPB;      
options.c_cflag &= ~CSIZE;         
options.c_cflag &= ~CRTSCTS;        

options.c_cflag |= CS8;
options.c_cflag &= ~PARODD;
options.c_cflag |= PARENB;
options.c_cflag |= CMSPAR;

options.c_oflag = 0;
options.c_lflag = 0;
options.c_iflag &= ~(IXON | IXOFF | IXANY | IGNBRK);
options.c_iflag |= INPCK | PARMRK;

stty output:

speed 9600 baud; rows 0; columns 0; line = 48;
intr = }; quit = ^A; erase = <undef>; kill = ^P; eof = M-4; eol = M-`; eol2 = <undef>; swtch = M-^X;
start = E; stop = M-p; susp = M-6; rprnt = $; werase = M-6; lnext = 8; flush = M-^Y;
min = 182; time = 174;
parenb -parodd cmspar cs8 -hupcl -cstopb -cread clocal -crtscts
-ignbrk -brkint -ignpar parmrk inpck -istrip -inlcr -igncr icrnl -ixon -ixoff iuclc -ixany -imaxbel
-iutf8
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt -echoctl -echoke

test:

echo -e "\x30\x31\x30" > /dev/ttyO1

expected results:

000110000 000110001 000110000

actual results:

000110000 100110001 000110000

I can't seem to figure out where I'm going wrong. Like I said, the docs seem to say that it should work, and I know if I go into the kernel and hack omap-serial I can make it use mark/space parity. I don't want to maintain a hacked kernel for something so trivial though.

Any pointers would be greatly appreciated!

Answer 1

Never found out why the STICK parity wasn't working from userspace, so instead of mucking about with the termios hacks to try to support a 9bit UART, I simply jumped over to the PRU and everything's running smooth. Using STICK parity without issue.