We am trying to read large data in loop for this I have created test case which takes baud rate as input.
Steps followed:
-
Device entry already exists in the system -
Open the device using open system call -
Update the baud rate using “cfsetispeed” and “cfsetospeed” followed by “tcsetattr”( TCSANOW option is used) -
Read the data from the terminal using read system call in loop and read size is 255 bytes and with loop count of 100
Issues faced:
Read call becomes no blocking and returns “0” and perror says “No Error” with above steps and if the step 3 is not carried out read call waits and read happens in default baudrate(115200)
To check what exactly happens I used stty to check the terminal status and I see the it does print data completely post updating the termios structure
Stty results before step 3:
Name: /dev/ser2
Type: serial
Opens: 1
+edit
intr=^C quit=^\ erase=^? kill=^U eof=^D start=^Q stop=^S susp=^Z
lnext=^V min=01 time=00 pr1=^[ pr2=5B left=44 right=43 up=41
down=42 ins=40 del=50 home=48 end=59
par=none bits=8 stopb=1 baud=115200 rows=0,0
Stty results before step 4 which is not fully printed and I guess some corruption as well
Name: /dev/ser2
Type: serial
Opens: 2
+raw
-hupcl
-cread
min=00 time=00
par=none bits=5 stopb=1 baud=9600 rows=0,0
let me know the possible reason for such behavior and point out any steps that I have missed to carry out and i see that data bits bits are changed to 5 from 8 which i did not try to modify.