Pin muxing on NXP i.MX8M Plus EVK

[Jonarie]

Hi,

I'm trying to Mux ECSPI2_SCLK to GPIO5_IO10 (output) and ECSPI2_SS0 to GPIO5_IO13 (input).
But something (at least for me) unexplainable happens, when I configure GPIO5_IO13 as Input with weak Pull Down [ pad = ( pad & (~0x1f6) ) | (1 << 8); ] , the pin has like a capacity, similar to a connected capacitor. If I connect it to 3.3V via a Jumper wire, it holds the voltage until I short it with GND.

This capacitive bahaviour is so strong, that most of the time its not possible to pull the pin down with another output pin.
That results in a "between state" of this pin, where it is at aprox. 1.8 V and still reads as high (see attachment).

My board rund QNX 7.1 btw.

I hope someone can help me with my Issue.

Below is my initialisation code:

out32(iomuxc + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_SCLK), IMX_MUX_CTL_MUX_MODE_ALT5 | (1 << 4)); /* SCLK, as GPIO5_IO10*/
out32(iomuxc + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_SS0), IMX_MUX_CTL_MUX_MODE_ALT5 | (1 << 4)); /* SS0, as GPIO5_IO13*/

gdir |= trigger_pin; // GPIO5_IO10
gdir &= ~irq_pin; // GPIO5_IO13

pad_ctl = (pdir10 & (~0x1f6)) | (3 << 1); // GPIO5_IO10
pad_ctl = (pdir13 & (~0x1f6)) | (1 << 8); // GPIO5_IO13

In the bsp init_pads.c is the following configured for ECSPI2:

/**
* ECSPI mux and electrical properties.
*
* @return Execution status.
*/
static int imx_init_ecspi_pads(void)
{
/* ECSPI 2 */
/* CLK */
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_SCLK), IMX_MUX_CTL_MUX_MODE_ALT0);
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_INPUTx(IMX_IOMUXC_ECSPI2_CSPI_CLK_IN_SELECT_INPUT), 1);
/* MOSI */
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_MOSI), IMX_MUX_CTL_MUX_MODE_ALT0);
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_INPUTx(IMX_IOMUXC_ECSPI2_MOSI_SELECT_INPUT), 1);
/* MISO */
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_MISO), IMX_MUX_CTL_MUX_MODE_ALT0);
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_INPUTx(IMX_IOMUXC_ECSPI2_MISO_SELECT_INPUT), 1);
/* CS */
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_SW_MUX_CTL_PADx(IMX_IOMUXC_SW_MUX_CTL_PAD_ECSPI2_SS0), IMX_MUX_CTL_MUX_MODE_ALT0);
out32(IMX_IOMUXC_BASE + IMX_IOMUXC_INPUTx(IMX_IOMUXC_ECSPI2_SS_B_SELECT_INPUT_0), 1);

return 0;
}

[Jonarie]

EDIT:

In the meantime I recompiled the BSP with ECSPI2 disabled, but still the same behaviour.