AM3358: UART not reading

Biser,

I did what you suggested  and set pinmux registers and verify after boot that the registers were indeed set to the expected values. The behavior has not changed.

0x44E108C4    = 0x2C           /* [P8 38] UART5_RXD  */

0x44E108C0    = 0x0C           /* [P8 37] UART5_TXD  */

Let me explain a bit more about my setup. As stated before I have two Beaglebone Blacks, one is being used as a transmit and the other is a receive. UART5 is configured the same on both BBB at 19200 baud, which is the speed of the device they will be connected to, eventually. I have a simple program on my driver BBB spitting out "42" on the tx line as fast as the UART will allow and an O-Scope tied to that line to verify data is being sent over the tx. The tx line is connected to the other BBB rx pin and on this BBB I have a simple program running that just waits to read any data off the rx. Right now I do not even care if it reads the correct data, I just want it to read anything. Maybe I am trying to read the data incorrectly, but my method of reading works just fine on UART0. Below is the simple program I use to read, that works just fine on UART0.  

int main(int argc, char *argv[]) {

 printf("Running data tx write...\n");

 fd = open("/dev/ser2", O_RDWR); //ser2 is the directory where UART5 lives UART0 live under ser1, which works fine.
 memset(in_buffer, 0, sizeof(in_buffer));
 if (fd > 0){

  cout << "File Open and descriptor = " << fd << endl;;
  read(fd, in_buffer, 2);
  cout << "Data from RX: "<<  in_buffer << endl;
 } else {
  cout << "Did not open file. \n";
 }

return 0

}   

This program will wait at the read() line till data is received and then exits.

Any other ideas?

Thanks,

Jason

Sorry, we do not support QNX so there is no way to replicate this. Have you checked if you have the same issue under Linux?

Biser, 

Yes, I did try on Linux, but was unable to get UART5 to work even for tx, but I did not spend nearly as much time investigating that, since my requirement is that I need to use QNX. Thank you for the suggestion, I understand you do not support QNX here. I have a query in with QNX as well on this. They recommended I put in a question with TI, since the UART is part of the AM3358 processor.  If you have any other ideas to try, I am open to suggestion, otherwise, thanks again for trying to help, I appreciate it. 

Jason

Jason -- you mentioned that you connected Tx of one board to Rx of the other board. Did you connect the grounds of the two boards together to make sure they have a common reference?

One other thing that comes to mind is potentially to try sending a '\n' across the line in case there is any kind of line buffering or anything going on (e.g. that's something you see with operations like printf which won't flush the data to stdout until it hits the end of the line).

Does the driver use DMA? If so, did you fill in the appropriate DMA events?

Brad, 

Sorry, I thought I had responded to this. I was making sure I was sending '\n' across the line, which was required. I made some progress on getting this to work, but as it stands right now, I do not think the driver use DMA for UART's 1-5. Because of this and another behavior I have found, which is all data read on RX is echoed back out on TX (seen with using an O-scope), the QNX support engineer and I think there is a bug with the QNX driver. We are now waiting to hear back from their BSP team to verify. Thanks for the suggestions. 

When I find resolution to this problem, would you like me to post it?

Thanks, 

Jason

Jason wilkins said:

When I find resolution to this problem, would you like me to post it?

I think that would be useful as long as you're not violating any confidentiality agreements, etc.