Unanswered Questions

18,807 questions with no upvoted or accepted answers
15
votes
0answers
692 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 ...
10
votes
2answers
296 views

Contact a very small area (impedance matched)

In my current project, I want to apply a voltage to a capacitor (top electrode on a thin film heterostructure) very rapidly. Since capacitors have their own charging rate \$(\tau = R \cdot t = R \cdot ...
8
votes
1answer
897 views

Design of cavity filter

I try to design a Chebyshev bandpass filter for 6 GHz as a coaxial cavity filter. I know that the filter can be designed with the aid of the coupling coefficients between the resonators and the loaded ...
7
votes
1answer
260 views

Can somebody please explain to me the principle of a T-T Earthing system?

How are the transformer, consumer's side and the generator earthed in a T-T Earthing system? I seem to understand that the generator and its frame should be earthed separately; The neutral of the ...
7
votes
2answers
279 views

ARD00280 Microchip Energy Reference Schematic Live and Neutral Swapped?

Looking at the Microchip Energy Chip reference design I noticed that the power is being sampled from neutral. My first reaction to this was this is backwards, that the power should be sampled from ...
6
votes
1answer
162 views

How to generate different noise in LTspice from run to run

I'm trying to simulate noise in my circuit, and ideally want to get a histogram of a certain parameter affected by that noise over many runs. However, when I use the white() command in LTspice, or ...
6
votes
1answer
272 views

DDR3 Data Errors

I am looking for post layout solutions for DDR3 data errors. I have a PCB with a FPGA and a 2 banks (2 rank) DDR3 ram setup. Data errors occur either when the RAM (FPGA is not confirmed, but could ...
6
votes
0answers
152 views

Radio module resetting when fluorescent tube switched on/off

I have a PCB powered by an IRM-30-12 power supply (230VAC to 12VDC). On this PCB, I have a MRF24J40MD from Microchip and a Udooneo to drive it + a 5VDC regulator and the 3.3VDC of the Udooneo. After ...
6
votes
1answer
203 views

Subthreshold Analog Accelerator - How is current derived through two sub-threshold transistors in series?

Was browsing the following paper: Fick, Laura, et al. "Analog in-memory subthreshold deep neural network accelerator." 2017 IEEE Custom Integrated Circuits Conference (CICC). IEEE, 2017. When I ran ...
6
votes
1answer
887 views

Receiver issues on STM32H7 interrupt-based SPI

I want to configure a simple interrupt-based SPI slave transmitter/receiver on a STM32H7 MCU. Even though I have quite a bit experience with the older series of STM32 ARM MCUs, it seems that a lot of ...
6
votes
0answers
205 views

Incrementing net name for group in Eagle

I want to make 50 copies of the block below, but I need incrementing numbers on each of the net labels (these will go to a connector). I do not want each block connected to the other blocks. It would ...
6
votes
1answer
456 views

GPS Power consumption MTK3339 vs SirfIII for periodic logging application

I am currently working on redesigning a SirfIII based battery operated GPS logger. A MTK3339 based GPS module has been selected due to overall (advertised) performance. The GPS logger uses a ...
5
votes
0answers
145 views

Analyze protocol used for Futaba VFD display, 3 data pins

I take apart a Samsung SMT-C7140 HD Unit (made obsolete by cable company, a shame) and found a nice display that I could probably reuse. It is a Futaba GL07-00006A (13-BT-246GINK). I tried to find the ...
5
votes
1answer
204 views

How do I calculate a PCB antenna trace width?

I'm totally stuck here trying to find a single source that describes how to determine a PCB antenna trace width. I understand how to determine the length based on the targeted wavelength, but the ...
5
votes
1answer
167 views

Circuit stable in the Bode diagram, unstable in step-response

I am designing a simple current control circuit and trying to simulate it in LT Spice. The circuit is not optimized for some real-world application, it's more a learning method for me to get grip on ...

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