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Unanswered Questions

29,151 questions with no upvoted or accepted answers
24 votes
0 answers
3k views

Switch from JTAG to SWD with bitbang sequence on STM32F103VB

I am trying to switch from JTAG to SWD without any external devices. Why? Because I would like to use the SWO pin to send a stream of logging information to another device. To accomplish this ...
12 votes
1 answer
583 views
+50

How to understand a complex diode-resistor function generator circuit?

I'm reverse-engineering a CRT anti-pincushion circuit and it uses a complex diode-resistor circuit to approximate the function \$X-k×X×Y^2\$, where \$X\$ and \$Y\$ are the deflection voltages. My ...
8 votes
1 answer
309 views

Clock generator output off by a factor of sqrt(2)?

I'm using the Si5351A-B-GM clock generator with the NX5032GA-25.000M-LN-CD-1 (25 MHz, 8pF) crystal. The fragment of the schematic is shown below (the rest of the schematic omitted for clarity): ...
8 votes
0 answers
272 views

Estimate base-spreading resistance from Gummel-Poon model

I'm attempting to calculate the base-spreading resistance of BJTs from manufacturer-provided SPICE models, which use the Gummel-Poon model. This Agilent publication (Internet Archive link here, if ...
8 votes
0 answers
2k views

Is JTAG faster than SWD for debugging on an STM32F with STLINK-V3SET programmer?

There is a new STLINK-V3SET programmer that someone dropped off on my desk today. It supports USB 2.0. My thinking is that if SWD is the bandwidth limiter in the signal chain then a new programmer isn'...
7 votes
0 answers
162 views

Extremely long net in Xilinx synthesized design labeled "async_path". What's it for?

I used Vivado to synthesize a small design for the Xilinx xc7k-160t-1. The design includes a fifo instantiated with Vivado's XPM macros which crosses clock domains from 100.8MHz to 200MHz. When I ...
7 votes
0 answers
409 views

x86 Motherboard Bring Up - Intel Tiger Lake UP3 CPU

For those who has experience with Intel x86 motherboard design and bring up. I'm in the middle of motherboard bring-up that has Intel Tiger Lake UP3 CPU. Seems like I had a good run so far at power-up ...
7 votes
1 answer
918 views

Modeling scalar control of PMSM

I have met with a scalar control algorithm for a permanent magnet synchronous motor. I haven´t heard about it before so I decided to develop a dynamic model to further analyze this control algorithm. ...
7 votes
2 answers
273 views

Phase shift near saturation mitigation in input stage amplifier -- How does this work, why does this work?

I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer. Apologies for the quality... this is the best scan I could find. The design is furnished with the ...
7 votes
0 answers
197 views

Frequency locking for averaging resampling

Background I've done a long one-shot measurement of a periodic signal by an oscilloscope. Thus, I've captured around 250 periods of a signal. The signal itself is a pseudo-random binary sequence at ...
7 votes
1 answer
1k views

IIP2 Second Order Intercept Rule of Thumb

I'm faced with the problem of explaining the harmonic production in a system where the second order intercept points of the cascaded components are unknown. As a way to bolster my explanation, I would ...
6 votes
0 answers
165 views

Vivante video memory size?

I'm using an NXP i.MX 8MP, with Vivante GC7000UL and GC520L GPUs. Using the Etnaviv open source drivers. For the life of me, I can't figure out how much video memory is made available to the GPUs, nor ...
6 votes
0 answers
210 views

Identify kind of cable with markings such as "WE-B 2 PAIR" on the jacket

While cleaning out our back yard shed, I came across a coil of cable of a kind that I have never seen before (image below). It was left here by the previous home owner, who worked in some kind of ...
6 votes
0 answers
7k views

How important really is the impedance of an USB 2.0 signal line?

The USB 2.0 specs requires a differential impedance of 90 Ohms and a common mode impedance of 30 Ohms (with some tolerance). This, by definition, gives a target of an odd mode impedance of 45 Ohms and ...
6 votes
0 answers
1k views

So can we just draw 500 mA from any USB port without enumeration now?

The USB Type-C Spec R2.0 defines the USB Type-C Current feature, in which the power Sink observes the voltage on the CC pin to determine how much current is available from the Source, which falls into ...

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