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Registered: ‎08-26-2020

Zynq-7000 MIO PIN state if unconfigured

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Hi,

 

I am using a XC7Z014S and I would like to know in which state a MIO pin is, if it is not configured. 

In UG585 Table 6-15 it says, they are 3-state in SD card boot mode, but do they stay in 3-state?

The use case is a prototyping board, where I would like to use signals, which are connected to MIOs, for another application, too. Therefore it would be nice, if I could just unconfigure the MIO pins and they go into 3-state.

 

Best regads,

Niklas 

 

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Registered: ‎01-22-2015

@Nizlas 

As you have found from UG585(v1.12.2), some MIO pins are automatically configured at power-up so that boot/configuration of the Zynq can proceed.  The particular pins that are automatically configured depend on the type of boot device as shown in sections 6.3.X of UG585.

After boot, instructions you have placed in the boot image control configuration of the MIO pins as shown in UG585 in Table 2-5 (page 54).  Note that you can configure a MIO pin for 3-State Control and thus (via your firmware) make it an input.  When the MIO pin is an input then (as you want) signals connected to the MIO input can be used for another application.   However, note the CAUTION below Table 2-5 that a signal connected to a MIO pin must satisfy Vin restrictions – otherwise the MIO pin can be damaged.

So, I'm not sure what an unconfigured MIO pin looks like - I'm sure there is a default setting.  However, I think it safest to pay special attention to all the MIO pins that you use "for another application" and place instructions in the boot image to configure them exactly as needed for your application - and don't depend on the default setting.

Cheers,
Mark

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124 Views
Registered: ‎01-22-2015

@Nizlas 

As you have found from UG585(v1.12.2), some MIO pins are automatically configured at power-up so that boot/configuration of the Zynq can proceed.  The particular pins that are automatically configured depend on the type of boot device as shown in sections 6.3.X of UG585.

After boot, instructions you have placed in the boot image control configuration of the MIO pins as shown in UG585 in Table 2-5 (page 54).  Note that you can configure a MIO pin for 3-State Control and thus (via your firmware) make it an input.  When the MIO pin is an input then (as you want) signals connected to the MIO input can be used for another application.   However, note the CAUTION below Table 2-5 that a signal connected to a MIO pin must satisfy Vin restrictions – otherwise the MIO pin can be damaged.

So, I'm not sure what an unconfigured MIO pin looks like - I'm sure there is a default setting.  However, I think it safest to pay special attention to all the MIO pins that you use "for another application" and place instructions in the boot image to configure them exactly as needed for your application - and don't depend on the default setting.

Cheers,
Mark

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