Unanswered Questions
29,152 questions with no upvoted or accepted answers
24
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0
answers
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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 ...
- 116
12
votes
1
answer
598
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+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 ...
- 11.6k
8
votes
1
answer
309
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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):
...
CommunityBot
- 1
8
votes
0
answers
272
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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 ...
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8
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0
answers
2k
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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
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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 ...
- 1,439
7
votes
0
answers
409
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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 ...
- 1,067
7
votes
1
answer
918
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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. ...
CommunityBot
- 1
7
votes
2
answers
273
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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 ...
CommunityBot
- 1
7
votes
0
answers
197
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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 ...
- 711
7
votes
1
answer
1k
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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 ...
CommunityBot
- 1
6
votes
0
answers
165
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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 ...
- 14.8k
6
votes
0
answers
210
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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 ...
Null♦
- 7,623
6
votes
0
answers
7k
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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 ...
- 1
6
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0
answers
1k
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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 ...
- 28.8k
6
votes
0
answers
793
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Understanding EGSM-900 (LTE 8 band) electromagnetic spectrum
I am trying to fully understand the physical layer of the GSM standard. For doing that I am looking at the E-GSM-900 band (mostly used in Europe). In my country these frequencies has been assigned to ...
- 185
6
votes
0
answers
1k
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How to protect single cell Ni-MH battery (overcurrent, undervoltage, overtemperature, etc.) during discharge?
Story
I am designing a boost converter for a battery powered board. I am planning to use single Ni-MH battery. The needed output voltage is 3V3. The device will be in deep sleep mode (drawing few ...
CommunityBot
- 1
6
votes
1
answer
7k
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RGBHV (VGA) to YPbPr Converter and Waveforms?
Purely for hobby, I am working on an RGBHV (VGA) to YPbPr (Component) converter circuit for old games consoles modified to output RGBHV on a VGA cable. From the game consoles, the RGB signal is taken ...
CommunityBot
- 1
6
votes
1
answer
1k
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Ethernet magnetics, discrete vs integrated: inductance value
I recently made a change to an EtherCAT-over-Ethernet design, where I moved from using an RJ45 with integrated magnetics to a low-profile connector with discrete magnetics because of size constraints.
...
CommunityBot
- 1
6
votes
1
answer
6k
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Run IAR Program without Debugging
I'm having a simple problem with IAR Embedded Workbench, programming an STM32 using an ST-LINK/V2 programmer. I'm trying to run a program that temporarily switches off the JTAG pins, so I can't run it ...
- 1,414
6
votes
1
answer
592
views
Charge mode piezoelectric signal conditioning
I have a charge-mode piezoelectric dynamic pressure sensor (datasheet link) that I want to read a signal from. If you look at the datasheet it says the sensor outputs are in a balanced and floating ...
5
votes
0
answers
114
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What's wrong with my bread maker?
I'm not sure if that's a place I can ask this question. I've got a 10 years old bread maker, that I've used about 50 times.
2 weeks ago, upon turning it on, everything looked and sounded usual (screen ...
- 293
5
votes
1
answer
185
views
Measuring Ethernet Impedance
I have a PCB, which was not designed by me. The Ethernet works intermittently between multiple copies, except for on one, where it works just fine.
I want to start troubleshooting at layer 1, and when ...
- 84.8k
5
votes
0
answers
118
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Why does output of this reverse bias noise source not have normal distribution?
I am trying to build a noise source based on reverse biased PN junction (i am trying to replicate this project https://altusmetrum.org/ChaosKey/ ). At this point i tried multiple iterations but so far ...
- 51
5
votes
0
answers
369
views
How to match an edge launch SMA connector to a pcb with coplanar waveguide with ground?
I'm trying to develop a pcb that is capable of handling signals over 6GHz and created a test board to see how the pcb and connectors perform. The pcb is a relatively low-cost 4-layer FR-4 TG155 board ...
- 123
5
votes
0
answers
101
views
Circuit with resistance equal to input resistance
I want to use a digital potentiometer, however, the digital potentiometer has a power limit, which means I can't apply the voltage for my application.
I am looking for a circuit which functions as an &...
- 9,270
5
votes
1
answer
1k
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Is my understanding of DRAM memory array topology in relation to "rows" and "columns" correct?
Assume a x16 DDR SDRAM module with 2b banks, which are made of 2r rows, which are further composed of 2c columns, where each column is 2w bits "tall". Assume that the interface is burst-...
CommunityBot
- 1
5
votes
2
answers
518
views
Help identifying Hall sensor (95B2h)
I am trying to identify a Hall-sensor located on a keyboard. There is one of these sensors underneath every key. One of them are broken and needs replacing. However, I cannot identify the component.
...
- 151
5
votes
0
answers
336
views
Bidirectional flyback converter design
I see a fair amount of questions on here about designing flyback converters, but I don't see any about designing a bidirectional DC/DC flyback converter, such that either side can be the primary and ...
- 9,270
5
votes
1
answer
101
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Do I need a clock crossing circuit for signals clocked by mirrored PLLs?
Assume that within an FPGA, I have two data streams that are being driven by two clocks. The two clocks are generated by 2 physically separated PLLs (still within the same FPGA), both of which have ...
- 442
5
votes
0
answers
2k
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STM32 - I²C Slave HAL Callback ACK
Objective: implement a single byte I²C slave on STM32.
Materials: STM32L452RE Nucleo-64 board, HAL Library, CH341 USB-I²C adapter(1), Artix Linux with Runit, Rhode & Schwarz RTB2004 oscilloscope
...
5
votes
1
answer
1k
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Custom RP2040 PCB Not Detected by PC
I designed a custom RP2040 to control some 24V LED strips. The official hardware design guide from the Raspberry Pi Foundation is what I followed for my design. It was then sent out to JLCPCB for the ...
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5
votes
1
answer
322
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Breaking capacity for fuses at mains inlet
Is there any official guidance as to what the breaking capacity should be for a mains inlet fuse? Assuming the appliance is intended to be fed from a normal domestic socket.
I understand that in an ...
CommunityBot
- 1
5
votes
1
answer
130
views
Is LTC2485 Arduino library missing information?
I'm using LTC2485 and got confused by the provided software code vs. the datasheet.
As described in LTC2485 I2C Data Format the LTC2485 ADC is 24 bits + sign ADC so like 25 bits.
In the given software ...
- 195
5
votes
0
answers
1k
views
What is the upper frequency limit for an op-amp integrator?
I'm designing a circuit to process a di/dt signal. As the input is the differential of the measured current, I have to integrate the voltage to provide a representation of the current. The duration of ...
Null♦
- 7,623
5
votes
0
answers
259
views
Cannot find what causes faults on DRV8353RH
I keep getting faults on a a new batch of ESC boards based on the TI DRV8353RH & Infineon IPT020N10N3ATMA1. Please consider:
When starting a motor at 48V - 56V the DRV asserts a fault after ...
- 111
5
votes
0
answers
221
views
Invisible magic components that spoil the Eagle preview
You know, after the eagle board design is finished, you can see the card on the preview screen.
I'll show you two examples. There is no problem with one. The card is centered on the preview screen.
...
- 1
5
votes
0
answers
280
views
Detection of CT secondary subsidence current
In utility power system protection we have a protection function called "breaker failure" protection. This protection is used to take appropriate action if/when a circuit breaker fails to ...
- 3,497
5
votes
0
answers
603
views
Drift with Madgwick algorithm with fast movements
I am trying to correctly track orientation of a sensor with accelerometer and gyroscope using the open source Madgwick algorithm. The algorithm returns quaternions which represent the rotation between ...
- 175k
5
votes
0
answers
96
views
What complications arise when designing a USB device sharing switch?
I wish to design and build a USB switch capable of transferring one USB keyboard between one of two computers. I wish to automate the process of unplugging the device from host A and plugging it ...
- 151k
5
votes
0
answers
177
views
Potential issues with mounting tiny PCB directly to piezo transducer?
I am designing a very small signal conditioning daughterboard with the intent of mounting it directly underneath a cylindrical piezoelectric force device/"sensor" to rectify and filter the ...
- 121
5
votes
0
answers
277
views
SD card SPI initialization Check Pattern Fail
I'm trying to interface a Swissbit 512MB (S-450u Series) SD card (datasheet here) with an ARM microcontroller through the card's SPI interface. The datasheet for this card says it's fully compliant ...
- 61
5
votes
1
answer
308
views
RFID reader array using row/column RF switches (multiplexers)
I need an 8x8 grid of RFID readers arranged on an 8"x8" board. The RFID tags will be placed only millimeters above each antenna.
I was wondering if I could use one 1:8 RF switch (e.g. pSemi PE426482) ...
CommunityBot
- 1
5
votes
0
answers
316
views
ATTiny85 clock speed problem
Using an ATTiny85 and an Arduino loader I created a simple device for turning on an exhaust fan based on a light sensor. The ATTiny85 turns on the fan after activating a warning light and sounding an ...
- 185
5
votes
0
answers
148
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What is the relation between resonance frequency and piezoelectric charge coefficient?
We know that the maximum power is lost at the resonant frequency,where the impedance is minimal. On the other hand, when the impedance is minimized, the charge coefficient is maximized. In resonance ...
- 175k
5
votes
0
answers
147
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Differentiator circuit sees noise on PCB after 2 min
I'm new to PCB design, and looking for some advice. I designed a PCB shield and I'm seeing a lot of noise in my differentiator circuit. The circuit will run perfectly for about 2 min and then all of ...
5
votes
0
answers
870
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PIN Photodiode gamma detection amplifier circuit - rectangular wave output
I've been working on a project recently, where I need to build a device which detects gamma radiation and can be used for gamma spectroscopy. I've done some research and found many interesting ways of ...
- 53
5
votes
0
answers
256
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Strange I2C communication
I am currently trying to test the SHT3x series humidity sensors by Senserion. I have their EK-H4 evaluation kit to get data from the sensors. I can plug in the sesnsors provided with the kit, and all ...
- 12k
5
votes
0
answers
2k
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Altium Designer: Copy room format does not modify polygon net name
I have a multichannel PCB with channels named U1, U2 and U3. I'm trying to copy the format of one channel to other two:
component placement,
routing,
polygons.
In the first place I was facing that ...
- 3,012
5
votes
0
answers
3k
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Correctly Using the Chan model in LTSpice
I am trying to use the Chan model to better simulate a transformer in my design. When I am making an equivalent transformer circuit, where does the Chan inductor go?
On the LTWiki it is implied ...
- 1