Global Pin Control Low Register

[davidzhou]

Hi,

I have K60 120M Tower. PORTB is configured as Alternative 2 as

  /* PORTB_PCR10: ISF=0,MUX=2 */

  PORTB_PCR10 = (uint32_t)((PORTB_PCR10 & (uint32_t)~(uint32_t)(

                 PORT_PCR_ISF_MASK |

                 PORT_PCR_MUX(0x05)

                )) | (uint32_t)(

                 PORT_PCR_MUX(0x02)

                ));

I have problem with toggling the PIN using Global Pin Control Low Register:

	PORTB_GPCLR = 0x4000400;    //(1<<26) | (1<<10);
	_time_delay(1);
	PORTB_GPCLR = 0x4000000;    //(1<<26) | (0<<10);

The pin is not toggling. Why?

If Pin is configured as GPIO, I can toggle it using gpio register.

Thank you,

David Zhou

[davidzhou]

What is the purpose to configure PTB10 as alternative 2?  I the pin is to be connected to external SPI CS, why can not configured as GPIO?

Thank you,

David Zhou

[kerryzhou]

Hi David zhou,

    From the reference manual, you can get that, PTB10, mux=2 is SPI1_PCS0, it is the SPI cs function.

If you want to configure the PTB10 as the GPIO, you must choose MUX=1, this is the GPIO function.

Wish it helps you!

If you still have question, please contact me!

Have a great day,
Jingjing

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[davidzhou]

Hi JingJing,

That's right. PTB10 , mux=2 is SPI1_PCS0. But I am confused a bit that how to control SPI1_PCS0? SPI1 in MCU is used as master, so how do I turn SPI1_PCS0 to low or high? I am using

PORTB_GPCLR = (1<<26) | (1<<10);

to set high and PORTB_GPCLR = (1<<26); to set to low. But the pin is not toggling. I don't know why.

Thank you,

David Zhou

[davidzhou]

Hi JingJing,

I figured out that if the pin is configured as PCS0, it is controlled by SPI driver.

Thank you,

David Zhou

[kerryzhou · Accepted solution]

Hi David,

    Yes, if you want to use the PTB10 as the SPIC CS function, you should configure it as the mux=2, and you don't need to control the GPIO, the SPI module will control the CS pin after you initialize the SPI module. If you want to control the GPIO pin, you must configure it as the GPIO function, not the SPI function.

Wish it help you!

Have a great day,

Jingjing

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[davidzhou]

Thank you , JingJing

David Zhou