Problem When running the sampleproj/servo_pwm.py script, SERVO_PWM remains high, even as the GPIO07 pin outputs a PWM signal.

Release A00, no modifications

Observed Behavior Servo PWM remains high even when PWM script is run.

GPIO07 at 40-pin header:

SERVO_PWM at servo header:

Root Cause Theory The pullup could be too strong; the transistor connection may not be consistent across boards. This is another issue that switching to a larger package transistor should fix.

Suggested Next Steps

• Switch to larger package transistor (as in issue #5 & 2)
• Test additional boards to ensure transistor connection remains consistent

Problem Board cannot be wake from software; the physical button must be pushed.

Release A00, no modifications

Observed Behavior When running the validation/sleep_func.sh script, the device does not wake until the power button is pushed.

Root Cause Theory An issue with how L4T interacts with the baseboard.

Suggested Next Steps

• Probe power logic signals to ensure sequencing is correct
• Read L4T documentation for power design

Problem The specified OLED display does not fit in the specified connector. Users cannot use the display.

Release A00, no modifications

Observed Behavior The connector is too small for the display.

Root Cause Theory Mistakes were made.

Suggested Next Steps Choose new connector for display.

Problem Users cannot use a fan, because the fan PWM signal is not in electrical compliance.

Observed Behavior GPIO14 provides a nice PWM signal, but the signal becomes less crisp as it goes through the level shifter. In both images below, the blue line is the FAN_PWM_LS node. Yellow: left = GPIO14, right = FAN_PWM_INV.

The transistor Q3 should invert the PWM signal, but does not appear to do so.

Root Cause Theory At 20kHz, it is unlikely the fan signal is switching too fast for the transistor. It may be due to a transistor misalignment; switch from the DMN26D0UFB4-7 to the DMN26D0UT-7, which is in a larger SOT-523 package, to avoid misalignments.

Suggested Next Steps Ask a more experienced engineer. May need a larger pullup, or more power control.

Problem Some USB ports on some boards do not respond when a USB mouse or keyboard is plugged into them.

Observed Behavior When a USB mouse or keyboard is plugged into one of the four type A ports, it occasionally does not work (the pointer does not move, no text appears on screen). This hinders the ability for the user to interact with the display, and to use the USB devices they need.

Root Cause Theory This is only present on some ports on some boards; it could be a manufacturing or hub chip error.

Suggested Next Steps

• Visually check all USB components to ensure there is no damage
• Ensure hub chip is strapped correctly
• Ensure USB layout guidelines are followed for signal integrity

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.

Problem On some boards, the power LED D6 does not light, even though the board completes its power-on sequence and has booted normally.

Release A00, no modifications

Observed Behavior

• The LED is the correct direction
• The board completes its power on sequence and the software functions as expected
• GPIO04 remains LOW at 0.6V, even though it should be driven HIGH upon power-up
• There is no measured voltage drop across R32
• There is an insufficient voltage drop across D6

Root Cause Theory The gate threshold voltage varies depending on the individual transistor. It could be that this transistor has a higher V_GS and does not turn on when GPIO04 is at 0.6V. Additionally, the transistor Q7 could be misaligned.

Suggested Next Steps

• Investigate behavior of GPIO04, which should be HIGH upon power-on. Remove R31 to ensure no loading effects from transistor.
• Change all transistors DMN26D0UFB4-7 to the DMN26D0UT-7, which is in a larger SOT-523 package, to avoid misalignments.

• Increase silkscreen size from 0.5x0.5mm to 0.438x0.7mm to make the text more readable.
• Add polarity for all ICs and polarized components to aid in soldering
• Add silkscreen on front for 40-pin header