C6747 pin OBSCLK no output

york yan said:

Now I am working on a C6747 board. The power on sequence of it is OK, including the CVdd,Dvcc and RESET. But I found pin RESETOUT still keep low after reset. I don't know why.

The TMS320C6747 datasheet states in Section 6.4.3 that /RESETOUT transitions from low-to-high a minimum of 6192 OSCIN clock cycles after the low-to-high transition of /RESET and /TRST.  Therefore, I would suggest you look at OSCIN to make sure there is a clock there.

york yan said:

Also, I found pin OBSCLK keep high(IPU), and no clk signal output on that pin. I wonder the default function of OBSCLK and the default output of OBSCLK.

Again, I would check OSCIN to ensure this is a proper clock into the device.

york yan said:

In addition, when I connect the emulator to my board, the TRST pin is still LOW and the emulator cannot connect to the board.

If /TRST is held low, you should determine why this is on the board.  /TRST is an input to the TMS320C6747 with an internal pulldown.  Are you indicating that the emulator is unable to pull this /TRST high and override the internal pulldown?

Thanks for your kindly help. I have figured it out.

I checked OSCIN, and the clk is actually in. I also checked the C6747 datasheet and found that RESETOUT and OBSCLK is defaultly set to be tri-state in pinmux. So they would be pulled down or high as to their IPD or IPU feature. When I enable the OBSCLK output, I surely observe the clock.

TRST now can also be high. The reason why it stay low before I still have not figured it out. What only I did is that I uninstall and install CCS3.3 many times.

After all, everything is working well now. Next I will debug the USB interface.

Thanks again.