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Based on the provided information, it appears that the issue lies in the tachometer reading of the fan on the Jetson AGX Orin module. The reading is weak and noisy, causing the fan speed to ramp up to 100% and stay there. The current workaround is to manually set the PWM to around half speed.
The suspicion is that there may be a pull-down resistor configured somewhere in the device tree or pinmux, which is dragging the tachometer signal down to an unreadable voltage level.
To troubleshoot this issue, I would suggest the following steps:
- Review the device tree configuration: Check the device tree configuration for the Jetson AGX Orin module to see if there are any pull-down resistors configured for the tachometer signal. Specifically, look for any entries related to the tachometer signal in the device tree file.
- Check the pinmux configuration: Verify the pinmux configuration for the tachometer signal to ensure that it is not being pulled down to ground. Check the pinmux settings for the tachometer signal and compare them to the settings for the same signal on the different compute module that works fine.
- Measure the voltage level: Use an oscilloscope to measure the voltage level of the tachometer signal at the input of the Jetson AGX Orin module. Compare this to the voltage level of the same signal on the different compute module that works fine.
- Compare the schematic: Compare the schematic of the fan connections on the custom carrier board to the schematic of the fan connections on the different compute module that works fine. Look for any differences in the circuitry that could be causing the issue.
In terms of the provided images, I would suggest reviewing the schematic for the fan connections on the custom carrier board (tachinputjetson) and comparing it to the schematic for the fan connections on the different compute module that works fine.
Additionally, I would like to point out that the provided information mentions that the same fan works fine on identical Tach Input circuitry going into a different compute module on the same board. This suggests that the issue may be specific to the Jetson AGX Orin module or its configuration.
In comparison to the other provided information, I would like to note that the issue seems to be specific to the Jetson AGX Orin module and its configuration, and not related to the thermal zones, OC limits, or throttling levels mentioned in the other text.
It’s also worth noting that the provided information mentions that the fan is 12V, but the voltage levels are shifted as necessary. This could be a potential cause of the issue, and it may be worth investigating the voltage level shifting circuitry to ensure that it is not causing the problem.
Overall, I would suggest a thorough review of the device tree configuration, pinmux configuration, and schematic of the fan connections to identify the root cause of the issue.
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