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Low-resolution HDMI (1280x720) #3

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wolframalexa opened this issue Aug 6, 2021 · 1 comment
Closed

Low-resolution HDMI (1280x720) #3

wolframalexa opened this issue Aug 6, 2021 · 1 comment
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A01 Fix Will be fixed in version A01 bug Something isn't working

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@wolframalexa
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Problem
The maximum HDMI resolution seems to be 1280x720, whereas the Jetson Nano achieves a resolution of 2560x1440. As a result, the display appears zoomed in.

Release
A00, no modifications

Observed Behavior

  • This is present on all boards, with the same module as on the official baseboard - probably a hardware design issue, and not a software issue
  • The resolution on the official Jetson Nano is twice that of "My Jetson Nano Baseboard"

Root Cause Theory
Resistor values may need to be tuned for better resolutions. Additionally, an EEPROM may be read to confirm HDMI resolution.

Suggested Next Steps
Investigate L4T behavior with regard to HDMI and resistor tuning on CEC line.

@wolframalexa wolframalexa added enhancement New feature or request bug Something isn't working and removed enhancement New feature or request labels Aug 6, 2021
@wolframalexa wolframalexa self-assigned this Aug 6, 2021
@wolframalexa
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The current theory is that the load switch (U10)'s calculated current limit, 55mA, is far below its capability. In limiting the current it also limits the voltage, which causes the 5V_HDMI net to be at 2.2V. Not good! So we're raising the current limit to within the MT9700's capability (0.6A) in the next revision. While this might seem like a significant increase, the main function of this load switch is to detect a short and prevent damage to the board - which setting the current limit higher does.

@wolframalexa wolframalexa added the A01 Fix Will be fixed in version A01 label Aug 11, 2021
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A01 Fix Will be fixed in version A01 bug Something isn't working
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