Interpreting HIGH and LOW voltages in case of boot detection

[Shafi]

Hi team,

I am trying to ensure the PMODE pin states in bootloader stage. According to FX3 datasheet I am interpreting  voltage above Vcc*0.9  as HIGH and interpreting voltage  below Vcc*0.1 as LOW . But how can I interpret voltage between Vcc*0.9 and Vcc*0.1?

For example, Vcc= 5v

So, from Vcc*0.9 = 4.5v I am interpreting it as HIGH

       Till Vcc*0.1 = 0.5v I am interpreting it as LOW.

But how can I interpret voltage between 0.5v and 4.5v ?

Could please tell me how do I ensure PMODE states by this method?

[AliAsgar]

Hi,

Could you let me know what values have you come across for the PMODE pins in between 0.5 and 4.5 V?

To check if the pins are Z,
1. Connect the pin to a pull up using a 10K resistor and check the voltage value at the pin.
2. After some time, connect the pin to pull down with a 10K resistor and check the voltage value at the pin.

If the voltage value of the pin in the step 1 and 2 remains same, then the pin is not in Z state, and has a fixed voltage value.
Whereas if the voltage value of the pins follows the pull up or pull down, then the pin is said to be in Z state.

Best Regards,
AliAsgar

[Shafi]

Hi,

In case of Vcc = 5v , For one particular PMODE pin I'm getting 2.5v. How can I interpret it? (as Low or High).

I'm following this article to know the PMODE pins states, there they mentioned 10k pull-down and 50k pull-up. But can I know why you are saying 10k pull-up and pull-down?

Thank you.

[AliAsgar]

Hi,

Could you please let us know why is interpreting PMODE voltage levels needed? 

Is a custom bootloader used or the ROM bootloader used directly. If the ROM bootloader is used directly, there is no need to pull up or pull down the PMODE pins as ROM bootloader handles it internally.

If the custom bootloader is used, use the same method given in the article you have linked to in the previous post.

Note : VIO1 has 1.8-, 2.5-, and 3.3-V typical. Please refer to Table No. 8 in the FX3 datasheet.

Best Regards,
AliAsgar

[Shafi]

Hi AliAsgar,

I am using custom bootloader instead of ROM bootloader, I configured my board to SPI boot mode but it is falling back to USB boot mode. To trace this issue I want to know the PMODE states.

Can you suggest any other method to trace this fall back issue please?

Thank you,

Shafi.

[AliAsgar]

Hi Shafi,

Could you let us know what voltage is the PMODE connected to internally?

The SPI can fallback to USB boot based on two issues:

1. SPI address cycle or data error

2. Invalid signature on FX3 firmware image. Invalid image type.

You could use the methods mentioned in this article to check the PMODE values.

You could also read the data from SPI flash and check if it contains a valid firmware image type.

Best Regards,
AliAsgar

[Shafi]

Hi AliAsgar,

Thank you for your response.

"Could you let us know what voltage is the PMODE connected to internally?"

PMODE connected to 1.8v internally.

"You could also read the data from SPI flash and check if it contains a valid firmware image type."

I have read the data from SPI flash, the firmware image is valid.Also, same firmware image is running fine when I write it in RAM.

May I know some more about falling back to USB boot when SPI address cycle or data error ?

Thank you,

Shafi.

[AliAsgar · Accepted solution]

Hi Shafi,

Please read through page 29 to 35 of the given application note thoroughly and make sure all the steps are taken care of.
https://www.infineon.com/dgdl/Infineon-AN76405_-EZ-USB_FX3_FX3S_boot_options-ApplicationNotes-v12_00...

Best Regards,
AliAsgar