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SysCtlClockget, Drive Strength

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I have two question need someone help me clear.

1) Someone say that SysCtrlClockGet of Tiva LaunchPad ( TM4C123GH6PM) is can not get clock rate of processor, is it right ?

2) Having many drive strength in GPIOPadConfigSet

#define GPIO_STRENGTH_2MA       0x00000001  // 2mA drive strength
#define GPIO_STRENGTH_4MA       0x00000002  // 4mA drive strength
#define GPIO_STRENGTH_6MA       0x00000065  // 6mA drive strength
#define GPIO_STRENGTH_8MA       0x00000066  // 8mA drive strength
#define GPIO_STRENGTH_8MA_SC    0x0000006E  // 8mA drive with slew rate control
#define GPIO_STRENGTH_10MA      0x00000075  // 10mA drive strength
#define GPIO_STRENGTH_12MA      0x00000077  // 12mA drive strength

 

I do not know how to choose one/seven modes to use?

Thanks!

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SysCtlClockGet has an error in Tivaware version 2.1.0.12573 so it does not read correctly if you set the clock to 80MHz.

(I don't remember if other frequencies are affected.)  Not sure in which version of the library this error was introduced, or whether it has been fixed.

One workaround is to remember what clock speed you set the processor to.

 

Edit: This message has a little more detail and links to how to patch Tivaware:

http://forum.stellarisiti.com/topic/478-how-to-calc-the-clock/#entry6818

 

(Also be aware that this call is not available on the TM4C1294).

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