Frank Vannieuwkerke

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10 years, 11 months ago.

KL25Z read pin control register not possible?

Am I incorrectly reading pin control registers?

Test code:

#include "mbed.h"
int main()
{
    unsigned int tmp;
    printf("PIN ALT STATUS\n");
    tmp = (PORTE->PCR[0] & PORT_PCR_MUX_MASK)>>8;
    printf("PORTE MUX value : )";
    printf("%04X\n",tmp);
}

The first printf is displayed, the second and third not (lock up at tmp=...?)

1 Answer

Frank Vannieuwkerke
poster
10 years, 11 months ago.

Never mind, found the answer on https://mbed.org/forum/mbed/topic/2866/

Adam Green wrote:

It appears that not all of the peripherals are powered up during the startup of the mbed device.

So, just adding a pin initialisation does the trick.

#include "mbed.h"
DigitalIn koko (PTE0);             // !! NEEDED BEFORE WE ACCESS PORTE->PCR[0]
int main()
{
    unsigned int tmp;
    printf("PIN ALT STATUS\n");
    tmp = (PORTE->PCR[0] & PORT_PCR_MUX_MASK)>>8;
    printf("%04X\n",tmp);
}

We also can check SIM->SCGC5 bits 9..13: these are the Clock Gate Controls for resp. PORTA, PORTB, PORTC, PORTD and PORTE. We cannot read PORTn->PCR[x] when its clock gate bit = 0 (port is not enabled). At startup, only one port is enabled : PORTA.

Accepted Answer