topic Re: GPIO setting in Kinetis Microcontrollers

GPIO setting

darshandpatel — Fri, 19 May 2017 07:12:14 GMT

hi,

I am using MKM34Z256VLL7 .In which IIC using bit banging for giving SDA and SCL high-low i am using PDOR register directly to set that GPIO bit . Problem is total port F is getting disturbed other port pins are getting toggle in setting SDA , SCL with PDOR register if i am setting and clearing with PSOR and PCOR respectively than this problem is not coming .

So, anyone can tell me the difference between direct use of PDOR and by PSOR .

Thank you.

Darshan

Re: GPIO setting

Hui_Ma — Tue, 06 Jun 2017 23:05:13 GMT

Hi,

From the GPIOx_PSOR register description, write 0 doesn't affect other bit status:

While, the GPIOx_PDOR register, write 0 will affect other bit status:

So, For example: if want to set PTF5 (I2C1_SCL), it need to use:

GPIOF_PDOR |= (0x1 << 5) ;

If want to clear PTF5 (I2C1_SCL), it need to use:

GPIOF_PDOR &=~(0x1 << 5);

Wish it helps.

Have a great day,
Ma Hui

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Re: GPIO setting

egoodii — Tue, 06 Jun 2017 23:31:14 GMT

Or you can use the BME macros on GPIOF_PDOR to avoid the inefficient &= and |= ops for single bits in peripheral-address space.

Re: GPIO setting

darshandpatel — Sat, 01 Jul 2017 08:40:42 GMT

BME macro only useful , &= and |= ops giving undesired output.

Re: GPIO setting

darshandpatel — Sat, 01 Jul 2017 09:04:27 GMT

And why that and,or ops giving such type of behavior.?

Re: GPIO setting

egoodii — Sun, 02 Jul 2017 16:43:25 GMT

Sorry, I am not directly familiar with the byte-wide GPIO scheme in the KM series. I agree, there is no 'obvious' reason that |= 'ones' and &= 'not ones' should fail, although I couldn't find a direct description as to whether reading GPIOF_PDOR would always return the exact contents of the output holding register, OR the pin state.