Hi, I have removed C236. 1.2V and 3.3V are nice and stable. Here is a scope capture. TCK (green) is 5V/div, all others are 0.5V/div. Signals are a tiny bit noisy because I couldn't have one GND per scope probe, the only probe GND used is that of TCK. In previous measurements, when I managed to connect the probes' ground, there was no noise on the measurements. I have "beeped" the pin, the board seems to be as per layout. Highlighted net is XRSn. The pin between R206 and C236 "beeps" with the ninth pin from the closest corner of the MCU. Unless the MCU was rotated in production (and I don't believe it was, I have triple-checked), the closest corner is pin 132, which would make the XRSn signal arrive on pin 124, which is as indicated on the datasheet page 17. Unless the PCB is not as per layout, the XRSn goes nowhere but to the MCU, so there shouldn't be anything to mess with the signal. Here is a photo of the setup. The debug connector (8pts) is really close to the MCU. Then there is the adapter board on top, to convert the 8pts connector into a standard JTAG 14pts connector (the little wires on the side bring the 3.3V, with a cap on the adapter board to stabilize the voltage seen by the debugger). Then the XDS110 right there. This is much shorter than the specified maximum length of 15cm. Are you certain the Vddosc grounded wouldn't cause the issue ? Best regards, Adrien
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