tms320f2808, CCS 3.3 Setting Gpio from assembly?

Tjarco Boerkoel

Hello,

Some functions in C-software examples are written in Assembly language but I haven't got much experience with Assembly. So I tried to 'learn' writing to the Gpio in assembly by first writing the code in C and selecting the 'mixed mode' option after building.

The result in Mixed mode after build is:

GpioDataRegs.GPBTOGGLE.bit.GPIO34 = 1;

MOVW DP,#0x01BF
OR @14,#0x0004

When I copy the generated assembly code into a assembly file and build + run, the GPIO pin isn't changing. The Gpio34 pin has been configured as GPIOI (GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0; // GPIO).

Is this the right method to toggle GPIO pins in assembly? Could someone help me out?

Best regards,

Tjarco

/edit/ when I try to change GPIO31 of port GPIOA in assembly, the I/O pin changes.

over 17 years ago

0 Lori Heustess over 17 years ago

TI__Guru* 93800 points

Tjarco,

Make sure the pin is also configured as an output in the DIR register. The MUX and DIR registers are EALLOW protected so make sure you set this before writing to them ie asm(" EALLOW");

-Lori

0 pete darnell over 17 years ago

Intellectual 340 points

Hi Tjarco,

You are going the wrong way! You should not be going from C to assembler ( hard to harder), you should be going from C to Visual block diagram (hard to easy) [;)].

Here is the VisSim program to toggle the single GPIO34 bit (port B bit 2) at 2 Hz on the F28335:

VisSim automatically setups up all GPIO mux, direction and enable bits. It will also setup qualification if you need it. It will also warn you if you use a GPIO pin for 2 different purposes, like SCI peripheral and direct GPIO.

You can download a 2 month free trial here.

And watch some VisSim movies here.

Regards,

Pete

0 Tjarco Boerkoel over 17 years ago

Expert 1725 points

Thank you all!

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tms320f2808, CCS 3.3 Setting Gpio from assembly?