mx6ul tamper pin to gpio

[jiangyaqiang]

HI :

  How can i config a tamper pin to a gpio ? for example , how to config IOMUXC_SW_CTL_PAD_SNVS_TAMPER0 to gpio5_0.

  refer to the document of mx6ul IMX6ULSRM.pdf , I know that , it has to config TAMPER_PIN_DISABLE[1:0]., which is found in

  chapter 5 "Fusemap": 0x430[21:20]. but how to access it ?

  Could anyone please give me a hand ? I'm confuse about it for sometimes .

[Yuri · Accepted solution]

Hello,

      You may use U-boot to read / write (once) fuses.

For example, u-boot command to read TAMPER_PIN_DISABLE is

       
   => fuse read 0 3

Definition of TAMPER_PIN_DISABLE[1:0] are as following :

        00 - enabled, TAMPER0-9 used as TAMPER detection pins.

        01 - disabled TAMPER2-4 and TAMPER7-9 used as GPIO.

        10 - disabled TAMPER0-1 and TAMPER5-6 used as GPIO.

        11 - disabled TAMPER0-9 used as GPIO.

   So, for the mentioned U-boot command, If bit [21:20] is 11, then all the ten
tamper pins are programmed to GPIO mode.

Have a great day,
Yuri

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[ericnelsonaz]

Hi Yuri,

I'm having trouble getting this to work.

Bits 20-21 are set to 11 on my system:

=> fuse read 0 3

Reading bank 0:

Word 0x00000003: 7031006e

But I'm unable to change SNVS_TAMPER1 to alt 5 (GPIO) using register IOMUXC_SW_MUX_CTL_PAD_SNVS_TAMPER5:

=> mm 020e0020

020e0020: 00000010 ? 15

020e0024: 00000000 ? -

020e0020: 00000010 ? =>

I'm running on an i.MX6UL, rev 1.1:

CPU:   Freescale i.MX6UL rev1.1 528 MHz (running at 396 MHz)

CPU:   Automotive temperature grade (-40C to 125C) at 36C

[qinghuazhu]

Hello,

      How do you set the value of Bits 20-21.Can you tell me your command?

      And how do you know TAMPER_PIN_DISABLE is Bank 0 Word 3?

      which document descript the register?

     Thanks.

[ericnelsonaz]

Hi Zhu,

The TAMPER_PIN_DISABLE field is found in the reference manual on page 214 (Table 5-9), though you can't search for it directly because of word wrap.

Search instead for "TAMPER_PIN_DIS".

[qinghuazhu]

Is it the "35.5.14 Value of OTP Bank0 Word3 (Configuration and Manufacturing Info.) (OCOTP_CFG2)"?

I can't set its value use uboot command:

=> mw 0x21bc430 0x0030002f

=> fuse read 0 3

Reading bank 0:

Word 0x00000003: 0000002f

=> md 0x21bc430

021bc430: 0000002f /...

=>

I don't know how to change its value.

Can you help me?

[ericnelsonaz]

Hi Zhu,

I don't think anyone wants to say (myself included), because you can brick a device, but the command to write fuses is "fuse prog", and to set those bits, you might do this:

=> fuse prog 0 3 0x0030002f

[qinghuazhu]

Hi Eric,

Thanks very much.

Unfortunately, I'm using G3, I can't use tamper pin as nomal GPIO.

and may you explain "tamper gpio" for me?

What does it mean?

Thanks.

[ericnelsonaz]

Hi Zhu,

Sorry, but I'll have to refer to others for the explanation of tamper gpio.

[qinghuazhu]

做工业级应用，一般会选择G2版本，如果使用了G3版本，则其以下GPIO只能做tamper GPIO,不能做普通的GPIO：
CTL_PAD_SNVS_TAMPER0～CTL_PAD_SNVS_TAMPER9 10个GPIO。
可以通过烧写掉以下fuse来将其设置为一般的GPIO:
G3 version CPU is for POS machine design, not as the G2 for industry, which the follow fuse is 00 and need you burn it to 11 to enable tamper0-9 to normal gpio, Pls check your reference manual
TAMPER gpio 是Pos机上用的，检测攻击，数据会自毁。

[Yuri]

Hello,

  "If TAMPER_PIN_DISABLE[1:0] fuse is programmed to "11 - disabled TAMPER0-9 used as GPIO",

then the tamper pins are in gpio mode, you do not need to configure iomux."

Regards,

Yuri.

[ericnelsonaz]

Thanks Yuri

[ericnelsonaz]

Hmmm. The pin is acting like a GPIO even though a read-back of the mux register doesn't show ALT5.

[jiangyaqiang]

Thank you very much