Question, i.MX25 KPP port usage

[Aemj]

Hi team,

I would like to ask about KPP port of i.MX25.

My customer plans to use KPP_ROW6(V5 pin) port of i.MX257 as a GPIO output.

The customer believes that the KPP_ROW6 pin can be used to output High or Low at any desired timing.

Is it true?

Please let me know if you have any concern on that.

Thanks,

Miyamoto

[fabio_estevam]

There is no GPIO functionality associated with this particular pin.

Regards,

Fabio Estevam

[Aemj]

Hi Fabio,

Thanks for your reply but I need more detailed explanation on that.

I think the port, KPP_ROW6, can be configured as an output port by configuring Keypad Data Direction Register (KDDR).

And I think one can control the output level of KPP_ROW6 by writing 1 or 0 bit into KPDR[6].

Am I wrong?

Thanks,

Miyamoto

[Yuri · Accepted solution]

Hello,

KPP_ROW6 (V5) pin has no GPIO functionality as Fabio mentioned.

Nevertheless, You are right, the KPP in itself allows to control pin state.

KPCR[KRE6] = 0 (Row is not included in the keypad key press detect)

KDDR[KRDD6] = 1 (ROW pin configured as an output)

KPDR[KRD6] = 1/0 (data)

Have a great day,
Yuri

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[Aemj]

Hi team,

The reference manual of i.MX25 says as below.

"The kKeypad port (KPP) is a 16-bit peripheral that can be used as a keypad matrix interface or as general

purpose input/output (I/O)."

Could you give your detailed reason why you say that KPP_ROW6 (V5) pin has no GPIO functionality?

Thanks,

Miyamoto

[Yuri]

Hello,

> why you say that KPP_ROW6 (V5) pin has no GPIO functionality?

Most of KPP signals can be configured as GPIO via IOMUXC_SW_MUX_CTL_PAD_KPP-...

registers, but the KPP_ROW6 does not have corresponding register.

   Only the following ones are available : 

IOMUXC_SW_MUX_CTL_PAD_KPP_ROW0

IOMUXC_SW_MUX_CTL_PAD_KPP_ROW1

IOMUXC_SW_MUX_CTL_PAD_KPP_ROW2

IOMUXC_SW_MUX_CTL_PAD_KPP_ROW3

IOMUXC_SW_MUX_CTL_PAD_KPP_COL0

IOMUXC_SW_MUX_CTL_PAD_KPP_COL1

IOMUXC_SW_MUX_CTL_PAD_KPP_COL2

IOMUXC_SW_MUX_CTL_PAD_KPP_COL3

Regards,

Yuri.

[fabio_estevam]

Now I see the response from Yuri and understood that it is possible to program the KPP interface to use the pin as an output.

Sorry for the confusion.

Regards,

Fabio Estevam