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Questions tagged [logic-level]

Logic level refers to the output voltage levels of digital logic, which is often 3.3 V or 5 V.

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2answers
146 views

How can a dominant state be the one with bigger voltage difference?

I am studying about CAN buses, and there is one thing I just can't find an explanation for. I understand that the idea of a wired-and connection is, that if any node is driving the bus to the dominant ...
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1answer
972 views

ESP32 logic HIGH/LOW level voltage, not working?

From ESP32 datasheet: In my case: VDD = 3.3V Vil (max) = 0.25 * 3.3 = 0.825V Vih (min) = 0.75 * 3.3 = 2.475V Theoretically: LOW LEVEL range is -0.3V to 0.825V HIGH LEVEL range is 2.475V to 3.6V ...
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1answer
87 views

Ultrasonic Sensor Serial Output Grounding Issue

I have a small circuit which uses a Maxbotix Ultrasonic sensor (Datasheet: https://www.maxbotix.com/documents/HRLV-MaxSonar-EZ_Datasheet.pdf) to take distance measurements and then transmit them over ...
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1answer
330 views

LCD SPI interface logic levels and SPI pinout

I am designing a circuit that includes this LCD and STM32L071 microcontroller. I have connected the LCD to 3V power net and the microcontroller to 3.3V power net. To communicate with the LCD, I need ...
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1answer
160 views

Through-hole solder sparking

Here is a simple example of what been happening to various pcbs when I play with them. I have an arduino powered by USB. Then a 5V and GND connected to a logic level shifter's HIGH and GND ...
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1answer
159 views

MOSFET Level Shifting 3.3V to 5V Floating

I have an XBEE chip that requires 3.3V logic levels and I'm having it talk to an ATMEGA328P that uses 5V logic (atleast in my application). I added in a MOSFET level shifting circuit to shift between ...
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2answers
635 views

High-side switch for 24V controlled by logic level

I mainly use this high-side switch design for 5V and with low current loads (under 100mA). Based on the VDSS (-50V), I thought I could energize this design with 24V as well. Apparently, I am making a ...
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1answer
199 views

Logic Level Converter not converting low logic level as expected?

I'm trying to convert 1.5V logic levels from a caliper data port to 3.3v to be able to read it with a microcontroller, using one of the sparkfun logic level converters. The product page mentions it ...
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1answer
631 views

How to correctly test a 4-channel Logic Level Converter?

I have a 4-channel logic level converter (it says Level Converter MH on its back and seems to be a very common one for Raspberry Pi and Arduino usage) and wanted to ...
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2answers
273 views

logic level converter does not get to 5v

I'm trying to control a 2 relay module with an Esp8266 esp 12-f. After a while, I realized that the GPIO from the ESP8266 was not going to drive the 5v needed for the relay to be activated. I only ...
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1answer
120 views

5V to 3.3V Converter

I have a problem in connecting Raspberry PI to an MCP3202. I am using MCP3202 at 5V and knowing that raspberry pi works on 3.3v. I have found a solution to convert from 3.3V to 5V using 74HCT244. And ...
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3answers
1k views

Small logic level converter 3.3V to 5V [closed]

I'm working on a small group project of 25 units using ESP-12F controllers that I need to fit into a relatively tight space. The project communicates with some WS2812b LEDs and takes a 5V power source ...
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1answer
57 views

Logic-level MOSFET not varying drain voltage [closed]

I have a series of FQP30N06L logic-level MOSFETs connected to a 3.3V logic controller. I am feeding the MOSFETs a PWM signal in order to vary the drain voltage, however, I am only experiencing a ...
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2answers
160 views

Logic Translation with Different Ground Reference

I have two chips which communicate with each other using 1.8v CMOS I/O (1Mbs UART). One chip is on the normal 0v ground plane, but the second chip's ground is at .7v (so its I/O operates at 2.5v for ...
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0answers
47 views

ESP8266 + Logic inverter on Tx = Failure to boot ?

I'm programming an ESP-12E module using the Arduino support package. My setup requires a logic level inverter on the Tx pin (only). I built the following which is working OK : simulate this ...
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3answers
3k views

Replace BSS138 with AO3400A in level shifter circuit

I have to use level shifter circuit to interface MAX31855 with Arduino running on 5V. I found easy to build level shifter circuit at SparkFun website. It is using BSS138 (datasheet) which I don't ...
0
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1answer
296 views

Logic level of CP2102

I want to have an USB-UART interface for my Controller. I was thinking to use CP2102 and thus was reading the data sheet. But I cannot figure out the logic level of the UART part of CP2102. Can you ...
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2answers
65 views

Are D flipflop inputs and clock thresholds the same for a given logic family?

I'm using an SOIC20 74ACT574 octal flipflop in a design. Vcc is 5 V, and GND is 0 V. The datasheets give V_IH (logic high input, guaranteed minimum) as 2.0 V and V_IL (logic low input, guaranteed ...
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2answers
780 views

Help with level shifting and ledstrip

I try to power a WS8211 based ledstrip. I first achieved to make it work with an Arduino UNO. The ledstrip needs to be fed with 12V power. Here is the working schematic : Once I apply power every ...
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2answers
511 views

How to drive a high-side logic-level power MOSFET?

simulate this circuit – Schematic created using CircuitLab Could you please tell me if it is possible to drive a high-side power MOSFET IRL40B209 with a high-speed logic gate optocoupler ...
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2answers
9k views

TTL, Totem Pole vs. Open Collector Output

What is the difference of these two ttl nand gates? What is a totem pole, what does it do and what is it used for? When connecting multiple ttl logic gates together is it better to use one or the ...
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2answers
78 views

Logic level for system lower than IC's recommended logic level

My system has a logic-level and logic-supply-voltage of 2.4V. I want to use a particular IC in it (which basically operates as a shift register), and the datasheet says the minimum recommended logic ...
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4answers
1k views

Can you damage logic gates by connecting two outputs together and powering one?

As the title says, would this cause problems in a circuit, and if so, how do you get around it (other than connecting them both through an OR gate)? Furthermore, could you stop this with a buffer? ...
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1answer
76 views

Data source switch with simple logic level shift

I would like to hack a 3.3v UART controlled Self Balancing Scooter in away that it can keep old logic (control), but optionally it should be able to switch to external control data source. The ...
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1answer
87 views

ST10F269Z2T3 abnormal Input Logic Levels

We are using a ST10F269Z2T3 Microcontroller (Datasheet) in one of our old Designs. Among other things, the ST10 monitors the functionality of external devices using Standard logic Inputs. Eg.: Input ...
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4answers
349 views

Shifting a 2.7V digital signal to Arduino logical levels?

I'm pretty much a beginner in electronics and I'm currently working on a personal project, where I have a device, that is putting out a digital signal (square wave) that goes from 0V - 2.7V and I need ...
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1answer
1k views

Design Review: 3.3V Logic to 12V Logic (Uni-directional and Bi-directional)

I'm looking for feedback and improvements on my design below. Specific questions are at the end. I created this as an attempt to answer my own, previous question. From my feedback there, it seems like ...
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0answers
2k views

3.3V Logic to 12V Logic (Uni-directional and Bi-directional) [duplicate]

I'm looking to understand how to convert between 3.3V logic and 12V logic, in each direction individually and bidirectionally. I know this question has been asked before, but I'm overwhelmed with the ...
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1answer
456 views

Logic-Level Converter: How high is the power consumption?

Regarding the following schematic for a bi-directional logic level converter, can someone explain how to calculate power consumption? Can I use pullup resistors with higher values, e.g. 1M? I need ...
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1answer
65 views

Can a Z84C00 CPU directly drive 74HCxxx series logic?

I'm getting confused by the datasheet for the Z84C00 CPU, while trying to work out if I can use it to drive 74HCxxx chips, or if I need TTL-compatible logic (i.e. either 74HCTxxx or 74LSxxx). It's ...
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3answers
175 views

Can GaN FETs be driven directly by logic level signals?

I've gotten interested in using GaN FETs for their combination of fast switching speed and very low on-state resistance. Most of the eval boards (for example by EPC) use GaN driver chips such as ...
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4answers
2k views

Does a BJT controlled relay need protection diodes?

I am fairly new to electronics, so please pardon my mistakes. I am attempting to build a Wi-Fi controlled relay. The problem, however, is that the relay runs on 5 V, but my ESP-12E can only ...
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1answer
157 views

Logic Level Translator Operation

I'm trying to analyze the Sparkfun Logic Level converter found here: https://www.sparkfun.com/products/12009 A rough schematic is shown below: simulate this circuit – Schematic created using ...
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2answers
1k views

How can a Switching diode act as a level shifter?

I am following a schematic about a one-way logic 3.3->2.8 level shifting circuit. The hardware in question is a MCU output that drives 3.3V and the input of the UART interface of a SIM800 GSM Module....
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1answer
10k views

How to convert a digital signal from 24V to 5V

I have an industrial automaton that gives me a digital signal (24V or 0V) on its outputs and I want this signal to control an integrated circuit, but the integrated circuit only takes a TTL signal in ...
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1answer
1k views

RS-232 signal level inversion

Bit of a noob question but i'm having trouble understanding rs-232. I'm sending data out over serial on an Atmel XMEGAA1U chip located on an Atmel XMEGA Xplained pro broad. If i send binary 0000 ...
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5answers
7k views

How did people realize they could do logic with electronics? [closed]

How did people realize they could do logic with electronics? Are there anecdotes or records of the first realizations? I'm wondering about the first "eureka" moments.
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1answer
171 views

How can I have an ECL logic input for a CMOS logic gate

I'm working on a triggering system that uses a comparator to check if the signal is below a threshold value. I found a great comparator for the job, except its output is ECL logic. I wanted to use the ...
0
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1answer
302 views

Schmitt Trigger for logic level conversion voltages up to +-20V

I want to be able to safely convert any voltages above a threshold voltage of +-1V with a maximum voltage level of +-20V to the logic level (3.3V). I ended up using an op-amp to construct a Schmitt ...
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1answer
408 views

transistor logic level converter circuit

this my first time asking questions to electronic community. So, I hope you ll help me. My question goes like this: i have arduino Due board connected to this schematic ( http://i.imgur.com/Qx2xObc....
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2answers
88 views

FTDI232 and GNS FM9, what voltage

I have a GNS FM9 dongle, which is a RDS receiver that came bundled with a sat-nav, intended to be used as a receiver for TMC traffic reports (which are transmitted as part of the RDS data stream). ...
0
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2answers
1k views

How to shift-up logic signal from 3V3 to 5V for NeoPixel [duplicate]

I'm working with NeoPixel led strip and a microcrontroller which run at 3.3V. As you can read in the NeoPixel documentation using a micro with 3.3V out on pin require the ...
0
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0answers
168 views

How to convert this ASM diagram to register transfer level?

So we have this ASM diagram, which I have to convert into register transfer level. I have already done some similar examples and I will usually start with defining next-state logic, than output ...
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1answer
865 views

Unstable output in VT pin of HT12D decoder

Hi everyone, I have been recently working on a RF operated water pump project. For this purpose i bought a RF RX and TX module which has HT12E and HT12D chips as encoder and decoder. The D8 (Dout) ...
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2answers
174 views

Driving an input with a 12V 4k7 pullup from 3V3 logic

I have a board with 12V CMOS logic whose inputs are pulled up via a resistor. It was designed to interface from a board via open collector opto-coupler. Now I have a request to drive it from 3V3 logic....
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1answer
91 views

Interfacing two ICs with different thresholds

I'm trying to using an ADuM1251 (http://www.analog.com/media/en/technical-documentation/data-sheets/ADUM1250_1251.pdf) with an ATxmega32A4U (http://www.atmel.com/images/Atmel-8387-8-and16-bit-AVR-...
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1answer
243 views

Manual Probe method of finding JTAG pinout

There is manual Probe method of finding JTAG pinout on RIFF Box JTAG programmer, by measurement of voltage on JTAG pins while alternately setting on JTAG pins the logical level 1 and 0. Is it possible ...
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2answers
170 views

Translate low logic level to higher voltage range

I need to shift a digital signal from an MCU to a higher voltage range. The MCU outputs 0-5V and I need to give this Signal inverted to a higher voltage rail. In the picture you can see what I try to ...
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2answers
370 views

3.3v to 5v switch

I'm using a esp8266 which operates at 3.3v logic. I power the board with a 5v power supply dropped to 3.3v on the board. So I have access to both 5v and 3.3v. I need to make the 3.3v GPIO pin shift ...
0
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1answer
37 views

value of resistor when converting HC outputs to non-compatible inputs

Here's what I'm trying to do. I have a 32K EEPROM (IC1 is an AT28C256) with data burned onto it. What I want to do is select the address I want using shift registers and then load the output value (...