IMX7D BOOT_MODE0 and weim.OE

Technical Support
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1

Hi,

I have some questions about pin 91 which is also connected to weim.OE.

  • External pull-up

Previously another user asked about the external 100k pull-up on this pin, but did not get a clear answer. After reset, EPDC_D08 has an internal 100k pull-down, which will fight with the external 100k pull-up. The input to the inverter will be ~1.6V in this case. Is this intended? What is the VIL & VIH of the inverter? BOOT_MODE0 is sampled on rising edge of POR_B.

  • External pull-up 3V3 source

I would like to connect weim.OE to an FPGA. In low power modes, the FPGA IO can be switched off. This means that the the unpowered FPGA pin is connected to 3V3 via the 100k pull-up to 3V3. What is this 3V3 rail? Where does it come from - the module input or an LDO output?

I assume that it is therefore not possible to connect pin 91 to un-powered circuitry on boot, because any input protection diodes will pull pin 91 low…

Thanks
Paul

2

Hi @Prelith

Correct, there is an external 100k pull-up on the module plus there is an SoC internal 100k pull-down on pin 91. This is not ideal but it is not an issue for the recovery circuit. The threshold for disabling recovery is at 1V. After the module has been booted up, the internal pull-down can be disabled which means we do not have the fight anymore.

The external 100k pull-up is sourced directly by the 3.3V module input voltage. This voltage is not switched at all. Therefore, the pin 91 can cause back feeding issue to an external peripheral such as an un-powered FPGA. Either make sure the FPGA is also powered from the same module input power rail or add a buffer between the module and the FPGA.

3

This is the wrong Paul, I did not post this question

4

Hi,

We are sorry about this. There is an issue. We will correct this soon.

Best regards,
Jaski

5

Hi @Paul

Is the issue solved now?

Best regards,
Jaski

6

I know. Sorry again, this was just a test. We are still working on this wrong user assignment issue.

7

I didn’t submit it

8

Still getting me. Is this a dup name problem?

9

Yes, it is a bug. We change the username for the other user.
Sorry for inconvenience.

Best regards,
Jaski

10

Still getting me. Is this a dup name problem?