Why does the C6713DSK run at the wrong clock speed when DSP/BIOS is disabled for the Embedded Target-TI C6000 DSP?

With DSP/BIOS, I set the "User Init Function" to be GBL_setPLLto225MHz(). This function, implemented in core DSP/BIOS assembly source, sets up the board to run at that speed. I need to find an equivalent implementation for Non-DSP/BIOS mode. It appears the C6713 PLL is not set when DSP/BIOS is not enabled.

Without this fix, the processor runs much more slowly than expected for Non-DSP/BIOS mode (50MHz instead of 225MHz). When timer-based models are used, this results in interrupts happening at a correspondingly slow rate.

To reproduce this problem, generate code with DSP/BIOS enabled, run it, and then do it again with DSP/BIOS disabled. The problem only exists if non-DSP/BIOS code is executed after a power-cycle reset.

Answer 1

[MathWorks Support Team]

This bug has been fixed in Release 14 Service Pack 3 (R14SP3). For previous product releases, read below for any possible workarounds:

This is a bug in the Embedded Target-TI C6000 DSP in the way that the C6713 PLL is set for Non-DSP/BIOS mode. Our development staff is investigating this issue.

To work around this issue, you must execute one of the GEL actions before running the application on the DSP. In Code Composer Studio, go to GEL->Resets->InitPll. This will configure the C6713 with the correct PLL settings to run at 225 MHz. In the file c:\ti\cc\gel\dsk6713.gel, there are instructions for the user to hand-modify the file so that the PLL would be reconfigured by default.