Colibri iMX7 Dual 1GB compatibility issue with VF61 based custom Board

Hello Everyone,

We have developed our custom board in which already used “Colibri VF61 256MB” Module and it’s working fine. Now we want to upgrade our system in which we need to use the 1GB flash memory then We decide to use the “Colibri iMX7 Dual 1GB” module.

Now We plug the “Colibri iMX7 Dual 1GB” module in our custom board then module/Board does not boot.
Note: “Colibri iMX7 Dual 1GB” module is working fine in “iris” and “Colibri eval” board.

Our Test result:

  1. We have measured the voltage on Pin No. 91(RECOVERY) of “Colibri iMX7 Dual 1GB” and it was “1.2” Volt.
  2. We have measured the voltage on Pin No. 91(RECOVERY) of “Colibri VF61 256MB” and it was “3.3” Volt.

As the point of compatibility, both modules are pin to pin compatible except the ADC voltage range (1.8V instead of 3.3V).
Why our board does not boot with the “Colibri iMX7 Dual 1GB” module?

Is there any pin other difference between “Colibri iMX7 Dual 1GB” and “Colibri VF61 256MB” module? or we need to do any extra care if we use the “Colibri iMX7 Dual 1GB” module?

Please help us to solve our issue.

Thanks & Best Regards;
Nikunj Patel

Hi @nikunjp26

Thank you for using the community site. The Colibri iMX7D and the Colibri VF61 are compatible in its main features. However, there are some differences in the supported interfaces. One of the best way to compare the interfaces is to use the Pinout Designer Tool (https://developer.toradex.com/knowledge-base/pinout-designer) and select both modules.

Since the threshold voltage for the recovery pin is at 1V, I do not think that 1.2V is causing the issue. If pin 91 is left unconnected, it is normal for the Colibri iMX7 to have a voltage at around 1.6V, while the Colibri VFxx has 3.3V at this pin. The iMX7 as well as the VFxx module have an 100k pull up resistor on the module. Additionally, the iMX7 module has connected this pin to another SoC pin (EPDC_D08) which has enabled by default a pull down resistor. Is there anything connected to pin 91 on your carrier board?

Even though, I do not think that the lower voltage on pin 91 is preventing the module to boot, the easiest way to check whether the module goes into recovery mode is to connect the USBC cable into a host PC. If the PC enumerates the module as serial loader device, the module is indeed in recovery mode and would not boot.

Does the module release the reset output at pin 87? Do you see any output on the UART_A_TX output on pin 35?

Hi, Peter
Sorry for the late reply,

We checked that module in recovery mode but it does not show any USB device in Host Computer(Linux/Window).

Also, we have validated below interface on Iris Board and it’s perfect working.

  1. Ethernet → Tested OK
  2. ADC(AD0,AD1,AD2,AD3) → Tested OK
  3. UART(UARTA,UARTB,UARTC) → OK
  4. USB → OK
  5. GPIO[45,01,79,114,85,118,97,115,101,112,103,113,133,81,98,139] → OK

Still, we are not able to identify the issue related to Our board so please help us to find the solution.
can you share your email id so we will provide the comparison sheet of our board Vs IRIS Board so you have to better idea.

Thanks & Best Regards;
Nikunj Patel

Hi @nikunjp26

The best way is to start a new community question and enable the “Confidential (Only Toradex can see this question)” mode. This makes sure that no other user can see your comparison sheet. Probably it would be also helpful if you can send me the relevant parts schematics of your carrier board. I will keep it confidential.

please mention my name in the question in order to make sure I get assigned to the question.

Hi Peter,

Sorry for the late reply.

We check the “https://docs.toradex.com/103543-colibri-imx7-errata.pdf” errata sheet and review the below sentence then we feel that we have same issue.

The issue only appears if the module is tried to start directly from power up. If an additional reset cycle is initiated by pressing the reset button (additional nRESET_EXT cycle), it never occurs. The module works without any issue.

As per above sentence we try to press the switch [nRESET_EXT pin to low] during the power up but still board does not boot.can you please explain what is the actual process for (additional nRESET_EXT cycle)?

Please find the image of our module for more reference.

alt text

Thanks & Best Regards;
Nikunj Patel

Hi @nikunjp26,

Thank you for the update. Your module is definitely not affected by the errata. Only early versionf of the Colibri iMX7D with 512MB of storage were having sample qualified SoC. The 1 GB version of the module was introduced later. The first two letters on the SoC version states the qualification level. PC stands for samples while MC stands for mass product. Your device is a MCIMX/D5EVM10SC. This means it is a mass product device with a silicon revision of 1.2. More information, you will find in the NXP datasheet in section 1.1.

Pressing the reset button always recovered the affected devices. Since it does not work in your case, there is definitely another issue. Have you been able to send me the schematics of your carrier board for a short review? I have not seen a new confidential ticket with this document so far, but maybe I have missed it.