TMS320F28377S: TMS320F28377S LANCHPAD SCI ECHO SAMPLE

Hi Michael,

Did you flash the code to Flash and not RAM ?

Regards,
Gautam

Hi Gautam,

I did it both way. I flashed and it did not work, I push reset, it did not work, then I unplug and plug in the USB. I did try to disconnect JP1 3.3V power, plug the USB and then plug in the JP1, did not work. I tried run it from RAM, it did not work but with RAM I can not unplug the power or reset button.

Hi Michael,

What baud rate are you running at?  I assume you are running this through the virtual COM port via the FTDI chip?  I believe that at very high baud rates the FTDI chip can sometimes have issues matching the exact baud rate (see https://e2e.ti.com/support/microcontrollers/c2000/f/171/p/720873/2662520?tisearch=e2e-sitesearch&keymatch=SCI%20baud#2662520 

What clock source are you using (external XTAL or the internal oscillator INTOSC)?  

Hi,
We are running the TMS320F28377S LAUNCHPAD so we used the virtual com port via the FTDI chip. The baud rate is 9600 8 data, 1 stop, N parity.
Thanks,
-Michael

Hi Michael,

When the program doesn't work, do you still see the message from the DSP asking to enter a character? (or do you see nothing?)

Have you tried with a different PC or USB cable?

You could try setting up an ePWM to toggle a pin a some frequency. I'd be interested in whether the frequency is the same in the working / not working cases.

You could try and view the SCI TX and RX signals between the FTDI chip and the MCU on a scope, but I'm not sure there is a great way to do this without soldering of test wires to the pads of R16 and R30.

The message from the DSP to hyperterminal always work. I have not try with different PCB nor USB cable. I will try to measure the TX and RX signal and let you know.
Thanks,
-Michael

Hi Michael,

Were you able to observe the TX and RX signals? Did this help to determine a resolution?

Hi Devin,

I observed the TX and RX signals and they are fine (HIGH) with either echo program work or not work. I observed that when the system is not working, the D8 RED LED does not blink when I type on the keyboard. I think this is the issue with the FT2232H IC and it might not reset properly.
I am looking at the FT2232H reset circuitry, any thought?

Thanks, -Michael