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GPIO7[15] cannot toggle in Rev2.1 DSP revision on TMS320C6748BZWT

David Luca
Expert 2795 points

Hello,

We had the software built on Rev2.0 on this processor and we were able to toggle GPIO7[15] just fine, but on the new revision Rev2.1 it stays high all the time. The default settings are set in SYSCFG1->PUPDENA and PUPDSEL all enabled, CP[26]-CP[28] set as pull low. We are using the same code to toggle GPIO7[14], GPIO7[13], GPIO7[12] which toggles fine on those pins in Rev2.0 and Rev2.1. There is nothing else connected on this pin at the moment. Any idea why is this happening? This pin was meant for enabling a multiplexer chip on our boards which was disconnected to prove the problem. The problems is the same on 3 more boards using Rev2.1. XJTAG tests on bare PCB board said there are no short-circuits for this track to the 3V3 line. The environment is Code Composer Studio 5.3 and used StarterWare 1.20.03.03 to toggle it. 

Best regards,

David.

  • 0
    TI__Guru* 84110 points

    David,

    Is the pin driven high or pulled high? This could be tested by putting a 10k-Ohm resistor from GP7[15] to Ground and see what voltage the pin goes to.

    For debugging this, my recommendation is to use CCS and a Memory Browser window to go directly to the PINMUX and GPIO registers to figure out what is going on. Check the register settings that should control the function of the pin and then the GPIO state. The datasheet and User Guides will be your guide on register settings to expect and to change.

    Regards,
    RandyP

  • 0 in reply to RandyP
    Expert 2795 points

    Hi Randy,

    My PINMUX16 is configured as 0x88888800, pins set as GPIO, the pin was held high. There are no pull-ups on this pin, only a pull-down (4.7k) and the voltage goes up to 2.4V (instead of 3.3V) when set to high. Replacing the processor seems to have fixed the issue.

    Best regards,

    David.