i.MX ProcessorsのトピックRe: Using the com port on the iMX53

Using the com port on the iMX53

leonardfairclot — Thu, 18 Apr 2013 05:27:53 GMT

Has anyone created an application that opens the com port and listens to incoming messages and sends a response?

I'm writing in C and I believe that the "stdio.h" should have everything I need. When I try to open the port I get error messages. It doesn't seem to like the parameters:

int portnum

portnum = open("dev/ttys0", O_RDWR | O_NOCITY | O_NDELAY);

Re: Using the com port on the iMX53

weidong_sun — Thu, 18 Apr 2013 06:01:36 GMT

Hello,Leonard,

I have programed UART on i.mx51, I paster source code and Makefile here. you can refer to them.

Regards,

Weidong

Re: Using the com port on the iMX53

Yuri — Thu, 18 Apr 2013 07:20:07 GMT

Please use O_NOCTTY instead of O_NOCITY

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 06:11:33 GMT

Weidong Sun

Thanks, this was very helpful. Just a question for you. Is there a reason you use "ttymxc1"? I'm using the quick start board iMX53 and it only has one serial port on it. I was trying "ttymxc0", just curious if you knew what I should use for this board.

Thanks

Leonard

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 06:16:33 GMT

Hi Yuri

I have it compiling with a comport trying to open. I asked Sun and I'll

ask you as well, what port should I be trying to open? I'm trying to

open "/dev/ttymxc0" is this

correct? I also tried "/dev/ttymxc1".

Thanks

Leonard

Re: Using the com port on the iMX53

weidong_sun — Fri, 19 Apr 2013 06:22:39 GMT

Hello,Leonard,

you please pay attention to ttymxc0 on mx53QSB, this is UART1 hardware, on this board, UART1 is used by console. when system startup , all messages ouput to console via this port. So you had better not use it to communicate with other device.

Regards,

Weidong

Re: Using the com port on the iMX53

Yuri — Fri, 19 Apr 2013 06:33:47 GMT

In the same time there are no other UART connectors on the i.MX53QSB (except one for UART1).
Basically it is possible to use console.

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 06:37:45 GMT

Good point Wiedong, I need a serial port do you have any other suggestions? I could go USB to Serial but I really wanted to avoid that. What port are you using and did you have to configure the serial port before you were able to run your program? i was just reading about "minicom".

Thanks

Leonard

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 06:40:42 GMT

That's good news, is there something I need to run before trying to open a port within a program. What does "minicom" do?

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 06:41:53 GMT

So I should be using "ttymxc1"?

Re: Using the com port on the iMX53

Yuri — Fri, 19 Apr 2013 06:53:36 GMT

At first - for development / debugging - the "ttymxc0" may be used (in order to avoid problems how
to implement hardware connection with "ttymxc1" on the QSB)

Re: Using the com port on the iMX53

weidong_sun — Fri, 19 Apr 2013 06:56:23 GMT

Hello,Leonard,

UART4 & UART5 can be iomuxed by CSI0 port. On i.mx53QSB , by default these pins are used for carmera and connected to J13.

You may consider how to connect them outside and do UART test. In addtion, Don't forget to adjust BSP file: add these pins to mx53_loco.c.

You can get iomux pins mapping by mcimx53rm.pdf. please refer to it !

CSI0_DAT12--->UART4_TXD

CSI0_DAT13--->UART4_RXD

CSI0_DAT14--->UART5_TXD

CSI0_DAT15--->UART5_RXD

<Note: UART4--->ttymxc3; UART5--->ttymxc4, the level of these 2 ports are 1.8V >

Regards,

Weidong

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 07:13:31 GMT

Thanks Weidong

I'll try that, not tonight. When i run your app, I get "open uart error, please confirm if this device exist"I tried "ttymxc0" and "ttymxc1" with the same results. The open routine is returning a "-1", is this an error that can be looked up?

Thanks

Leonard

Re: Using the com port on the iMX53

weidong_sun — Fri, 19 Apr 2013 07:17:07 GMT

Hello,Leonard,

you please check all uart devices in path /dev/:

# ls -l /dev/ttymxc*

to confirm if uart devices have been driven.

Regards,

Weidong

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 07:22:23 GMT

Nothing is found. How do I add uart devices\drivers?

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 07:25:45 GMT

I have tty0-63 and ttys0-31. No ttymxc*.

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 07:34:36 GMT

Sorry, I was looking on my development PC, I found them on the development board. I have "ttymxc0-4" on the iMX53.

Re: Using the com port on the iMX53

weidong_sun — Fri, 19 Apr 2013 07:48:48 GMT

Ok, you can run your program on board, and check if UART has been opened successfully.

Regards,

Weidong

Re: Using the com port on the iMX53

leonardfairclot — Fri, 19 Apr 2013 07:49:06 GMT

The permission on ttymxc0 is "crw-------" where as all the others are "crw-rw----" could this be the issue? Chmod will not all me to change the permission. What do you think?

Re: Using the com port on the iMX53

weidong_sun — Fri, 19 Apr 2013 07:52:36 GMT

don't use ttymxc0. use others please ! For example , use UART4:

#chmod 777 /dev/ttymxc4

Then run your program.

Weidong