GPIO pin does not work to be set - Delfino (C28346)

Andreas Unterberger

Hi!

In my program I want to set the state of GPIO pins. But there are some circumstances which lead to the result that a pin register is not set to the correct state.

e.g.

GpioDataRegs.GPCDAT.bit.GPIO64 = 0 (result: 0)

GpioDataRegs.GPCDAT.bit.GPIO65 = 0 (result: 0)

GpioDataRegs.GPCDAT.bit.GPIO68 = 1 (result: 1)

GpioDataRegs.GPCDAT.bit.GPIO67 = 1 (result: 0)

GpioDataRegs.GPCDAT.bit.GPIO66 = 1 (result: 1)

This result is only generated if the program runs, if the debugger is used and the instructions are stepped over everything is set correctly as in source code.

I found out that inserting a NOP between every instruction does not change anything. But writing the same instruction doubled to the source line generates a correct result.

Isn't it allowed to use the bit registers in consecutive instructions?

what else could be the problem?

The CPU is clocked at 300MHz

Compiler Version: c2000_6.1.0

Code Composer Version: 5.3.0.00090

thanks for your help!

over 11 years ago

0 Bill Finger over 11 years ago

Genius 3735 points

If you look in the datasheet for the device, you will find that the digital outputs can be toggled only at a certain maximum rate, which will be less than the CPU clock rate.

If you put several NOPs, or insert a call to a delay function, you should see the behavior you expect.

Note: you can also use

GpioDataRegs.GPCTOGGLE.all = 1 << 66-64;

which will be faster as a read of the register is not required.

Regards,

Bill

0 Brett Larimore over 11 years ago in reply to Bill Finger

TI__Guru 57255 points

Mr. Unterberger,

You may also want to take a look at the following wiki page. I believe that it should explain the situation that you are seeing.
http://processors.wiki.ti.com/index.php/General_Purpose_IO_%28GPIO%29_FAQ_for_C2000#Q:_Back-to-back_DAT_register_writes_do_not_work_as_expected

Hopefully this helps!

Thank you,
Brett

0 Andreas Unterberger over 11 years ago in reply to Brett Larimore

Expert 1140 points

Thanks for the help!

This information is exactly what I was looking for.

kind regards

Andreas

C2000™︎ microcontrollers

C2000 microcontrollers forum

GPIO pin does not work to be set - Delfino (C28346)