TM4C129 Ethernet LED Polarity

Hello Mike,

Can you please send the code that you have to configure the GPIO as Ethernet LED and the Polarity Swapping?

Regards

Amit

Hi Amit,

Relevant code is below. I'm not sure if there's a better way to go about setting the polarity bit in reg 68, but this is what I tried.

// *** Ethernet Status LEDs ***
MAP_GPIOPinConfigure(GPIO_PF0_EN0LED0);   // PF0 is ethernet LED0
MAP_GPIOPinConfigure(GPIO_PF4_EN0LED1);   // PF4 is ethernet LED1
GPIOPinTypeEthernetLED(GPIO_PORTF_BASE, GPIO_PIN_0 | GPIO_PIN_4);

EMAC0_CC_R |= 0x20000;

Thanks for the help

Hello Mike

PF0 is a locked pin. You would need to unlock it for configuring the Pin to another function.

http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/374640.aspx

Regards

Amit

Amit,

Thanks for the advice, but the problem is still there.  I am able to get the LEDs working and functioning as intended, but with reversed polarity.

The problem seems to be with setting the POL bit in register 68.  Is there some recommended way of accessing this?

Thanks

Mike, 

Here is how I flip it:

  // Set Ethernet LED polarity to be active low
  HWREG(EMAC0_BASE + EMAC_O_CC) |= EMAC_CC_POL;

Jeff

Jeff,

Thanks for the help.

For me EMAC_CC_POL throws an undefined error, and hardcoding what I believe to be the corresponding hex value of 0x20000 gives the same results as before, it chokes while executing that line.

But since EMAC_CC_POL isn't defined I'm wondering if it's some problem using a previous version of TivaWare?

I currently have 2.0.1.11557a and defines for EMAC_O_CC register are:

//*****************************************************************************
//
// The following are defines for the bit fields in the EMAC_O_CC register.
//
//*****************************************************************************
#define EMAC_CC_PTPCEN          0x00040000  // PTP Clock Reference Enable
#define EMAC_CC_ECEXT           0x00020000  // EN0RREF_CLK Signal Source
#define EMAC_CC_CLKEN           0x00010000  // EN0RREF_CLK Signal Enable
#define EMAC_CC_CS_M            0x0000000F  // Ethernet PHY Clock Reference
                                            // Source
#define EMAC_CC_CS_MOSC         0x00000000  // MOSC
#define EMAC_CC_CS_PA7          0x00000001  // GPIO (PA7)

Which would explain why hardcoding the value doesn't work. It seems to be assigned to a completely different bit mapping.  This seems like a pretty significant change between versions.

Is it possible to get this to work on my current version?

I don't know why it is so different in 2.1, but I do know it works. :~)

2.1 has been out for quite a while - perhaps it's time to upgrade.

Jeff

This seems to have done the trick.

Flipping the bit after EMACPhyConfigSet successfully changed the polarity. I did end up having to hard code the 0x20000 value though so this may not be an ideal solution.

Still not sure why it was crashing all together when I tried changing the bit right after configuring the GPIO though. The PC just jumped to 0xfffffffe on that line.

This seems to work for now though so thanks for the help.