2 Carrier boards work with no issues. Aquilla booted on first try
We have 1 carrier board that appears to have some sort of fault.
Carrier board 5V is Active and stable
Carrier board also has 3.3V and 1.8V these are also active
CTRL_RESET_MICO# is high at 1.8V (it is not driven by anything on the Carrier board
We have probe the SOM power supplies. We see 5V is present at the input capacitors, but all of the power supplies are in the disabled state. 0V on both sides of output capacitors. For reference it appears there are 5 onboard power supplies (top side) all are disabled.
Any idea what signal or condition on the carrier board could cause this?
The linux console (UART_3) has no activity and no voltage present on the TX
Verified the SOM itself is functional by testing it on the Toradex Aquilla development board
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Power Management Issue Analysis
Based on your description of the Aquila AM69 not powering up on the faulty carrier board, let me help diagnose the potential causes. The fact that the SoM works on the Toradex development board but not on your custom carrier suggests a carrier board issue.
Key Power Management Signals to Check
According to the Aquila Family Specification, several power management signals could prevent the module from powering up (1)(2):
Critical Power Management Pins
CTRL_PWR_BTN_MICO# (Pin B93) - This is an open-drain input with 100kΩ pull-up to 1.8V STBY rail (2). Long pulling down (>5s) shuts down the module, while short pulling down turns on the module from off-state (2).
CTRL_FORCE_OFF_MOCI# (Pin B94) - This is an output for forcing the turning-off of the main power rail (2). This signal needs to be blanked (ignored) for the first 400ms during the power-up sequence (2).
CTRL_RECOVERY_MICO# (Pin B91) - Shorting to ground during power-up can affect boot behavior (2).
Power Supply Requirements
The Aquila modules are powered by a single voltage VCC with an input voltage of 5V ±10% (1)(2). Once VCC is present and within specification, the module powers up and starts normal operation automatically (2).
Debugging Steps
Check CTRL_PWR_BTN_MICO# - Verify this pin is not being held low inadvertently on your carrier board
Monitor CTRL_FORCE_OFF_MOCI# - Ensure this isn’t being driven low by your carrier board design
Verify all power management pins are properly handled according to the specification
Check for shorts on the VCC power rail that might prevent proper startup
Known Issues to Consider
There are several known errata for the Aquila AM69 V1.0 that could be relevant (3):
USB-related issues that might affect power management
Reset signal compliance issues (HAR-12387) where the module doesn’t properly comply with the CTRL_RESET_MICO# signal (3)
Power States
The module should transition from “No VCC” state to “Running” state when proper power is applied (2). If the on-module power supplies aren’t enabling, it suggests the module isn’t receiving the proper startup conditions from the carrier board.
I recommend carefully reviewing your carrier board schematic against the Aquila Family Specification, particularly focusing on the power management signal routing and ensuring no unintended connections are preventing proper startup.
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What about the other power management signals, such as CTRL_PWR_BTN_MICO# and CTRL_RESET_MICO#? Please also double-check that the PWR_1V8_MOCI output is not shorted to ground or overloaded, as it can handle a maximum of only 250 mA.
No, PWR_1V8_MOCI is not used. only routed to a header. Measuring this signal (with Carrier power) I see it is 0V and high impedance to GND
CTRL_PWR_BTN_MICO is not connected to Carrier 1.8V supply through 10K pull-up. measuring 1.8V on this signal at board power on
Also tried setting CTRL_WAKE1_MICO to high (1.8V) , when connected 0.9V is measured. Dropping external voltage to 1.2V and the measured voltage on Wake is 0.7V
Tested to see if the SOM power supplies are momentarily turning. Measured output caps with a scope but see no activity
Could you please specify the exact points you used for your measurements? I can only suspect that the SoM connector on your board may have a short circuit, which could be causing the power supply to shut down.
On the SOM itself we see 5 obvious DC/DC converters. Measuring at the input caps to these supplies we see the expected 5V. Measuring at the Inductor and output caps for these supplies there is no voltage under any condition. The supplies do not appear to be starting up at all
