OMAPL138 GPIO Simulation

Thomas S

Intellectual 600 points

Other Parts Discussed in Thread: OMAPL138

I tried to simulate (ARM926EJ-S Device Cycle Accurate Simulator) a simple GPIO application, that worked with the DSP.

The application configures the particular PINMUX registers and does the following GPIO access (to set all to input):

((CSL_GpioRegsOvly)(CSL_GPIO_0_REGS))->BANK[i].DIR=CSL_GPIO_DIR_DIR_IN*(unsigned int)(-1);

Before execution of this code the Processor Mode is 0x11111 (System)

This code ends up into an exception at vector address 0x00000014, which is "Reserved" according documentation of the ARM.

The Processor Mode is now 0x10011 (Supervisor)

Can anybody explain what can lead to this kind of exception?
What do I need to do to avoid this malfunction?

Best regards
Thomas

over 13 years ago

0 Thomas S over 13 years ago

Intellectual 600 points

I realized, that SYS/BIOS by default enables the MMU. But this doesn't explain the "Reserved" exception (vec 0x14). I would expect the data access exception (vec 0x10), what I get on the HW (Emulator->OMAPL138).

So I disabled the MMU in the SYS/BIOS settings (Target Specific Support->Arm->Arm9->Mmu: enableMmu=false)

Best regards
Thomas

0 Paul.Yin over 13 years ago in reply to Thomas S

TI__Genius 14405 points

Hi Thomas,

To run your application, you need to be in supervisor mode. It sesms that RTS library by default put you in the system mode. You need to make sure you are in supervisor mode when you arrive at main.c.

Do that either by chaning the CPSR register, or use a different boot.asm in your project.

Use the following link as a reference

http://processors.wiki.ti.com/index.php/Boot_Images_for_OMAP-L138

regards,

Paul

Processors

Processors forum

OMAPL138 GPIO Simulation