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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CAN Rx Line between STM32 and MCP2561

I discover a problem on my design, with a STM32F042K6 MCU and a MCP2561 Can Transceiver. I can send some frames on the CAN Bus but i can't receive any frames. When i put my scope probe on the CAN Rx ...
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85 views

5V digital output to 24V

I'm sure it is a simple solution but I am new to this so please take it easy. I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V ...
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49 views

PX4FLOW (Optical Flow sensor) - Powering with 5v. Does it work with OmniNXTF7 I2C SCL/SDA at 3.3v?

I want to use PX4FLOW with OmniNXTF7 flight controller. This flight controller has 3.3v I2C SCL/SDA and no PullUp-resistors. I use the PX4FLOW only with I2C port, with 5v at VCC (not 3.3v). Does ...
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38 views

How to passively shift logic levels to drive LEDs

I have an input signal that is either 2.7V (low) or 9.9V (high). Is there any way to use passive components (excluding op-amps) to turn an LED off when the signal is low and on when the signal is high?...
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55 views

Switch from 5v to 24v - 150kHz - 20mA

I'm looking for a way to amplify a signal from 5v -> 24v. This signal is a PWM with a frequency of 150kHz. Amplified signal will have a fixed load of 20mA to power a LED with a Vf of 1.25v. I've ...
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123 views

Using Mosfet with seperate Logic Converter and Arduino

I am trying to use an IRLB3034 with an Arduino even though it is not a logic level MOSFET. I am planning on using an LM2937 12v regulator like the schematic below: The connection going off the page ...
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42 views

The simplest “adaptive” downward level shift solution?

I want to build a level shifter circuit for the RX pin of my ESP-12S. The goal is to convert any level between 3.3V and 5V to 3.3V as I might use many USB to UART breakout boards with different output ...
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41 views

Serial Communication Between Android and Attiny85

I am planning to build a sensor module for smartphone using Attiny 85 as its microcontroller. The sensor module will have a USB type A and to connect to the smartphone, OTG is required. Serial ...
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15 views

Logic leves and protocol, interfacing HP39GS to arduino Wemos D1

Im trying to connect HP39GS scientific calculator to Wemos D1 arduino. It has TTL RS-232 serial port. Pinout is somewhat: Vcc, TX, RX, GND. Looks like HP39GS protocol for serial port is not pure RS-...
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51 views

Preventing overvoltage on serial pin

I am trying to send data through serial from a 3.3v Arduino to a 5v Arduino. I assume I can't just connect the 3.3v tx to the 5v rx because, when I program the 5v one I am assuming it will send 5v ...
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153 views

NPN: Not fully sinking to GND

I'm using an NPN to pull a 12v (5mA) signal low from an MCU (logic level). My problem is that when I pull the 12v line low, 7.4v are still present at the 12v side of the line using the circuit below: ...
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40 views

How do I wire a Rasberry Pi 3B+ to a WS2812b RGB strip?

I am working on a project where I need to use a WS2812b RGB strip. I am really worried because I have already burnt 2 Raspberry Pis with my wiring. I just want to show my schematics, and be assured as ...
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1answer
64 views

Driving 12v logic from an MCU

I'm looking to drive 12v logic signals (logic level shift) from a PIC24FJ MCU, which can do 3.3v and 5v logic. In one instance, I need to switch a 12v line to LOW, and in an other, I need to provide a ...
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68 views

Component recognition from marking code

I need help to recognize a dead component from a lab instrument control board. It is part of a TTL-serial interface, arguably a logic gate or some level shifter, in a TSSOP-14 package. You can see ...
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34 views

3v3 VLogic for DG212

I am curious if anyone knows if a Vishay DG212 works with VLogic being powered by 3v3? The only test conditions the datasheet speaks of are where VL is being powered by 5v. Here is the datasheet: ...
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46 views

High level present in a pin of a non-powered IC can damage it?

I'm using a TXS0108E to convert from 5V to 3.3V and vice versa. The schematic is below: In the datasheet, in section 6, I read the following: Voltage applied to any output in the high-impedance or ...
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100 views

How to explain and possibly avoid undervoltage on I2C bus?

I've been testing different sensors for the I²C bus with two host devices: Raspberry Pi 3B (3.3V), and Sitec S4 (5.0V). Since one of them, namely the Sensirion SCD30, had communication problems every ...
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99 views

Help needed in understanding MOSFET datasheet

I am trying to find a logic level MOSFET for 3.3V operation. In my case, I am trying to compare AOD510 & AO4402. AOD510: \$\mathrm{R_{DS(on)}}\$ @ 4.5 \$\mathrm{V_{GS}}\$ = 0.004 ohm but has no ...
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1answer
83 views

Logic level translations

Have you ever had any experience with an ADG3304 IC? I've prepared a circuit which allows to translate logic levels in SPI interface. I want my circuit to be compatible with both 1.8V and 3.3V logic ...
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42 views

Logic levels on tri-state buffer,

i am working on some CPLD-controlled SPI devices that will be daisy-chained together. I will be using 74VHCT126AFTTR tri-state buffers to disconnect the SPI and Slave Select lines on the device from ...
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79 views

Does logic shifter works on analog signals?

I am using a 5V sensors (MQX Gas Sensors) that is connected to an RPi. This sensor is then connected to an ADC converter then to a logic level shifter. I just followed the tutorial I saw on the ...
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2answers
168 views

How to analyze Microcontroller input-logic-signal without ADC?

I have a signal which is fed to one of the digital inputs of a microcontroller (PIC16F18326). The signal is shown in the image-1 below. This is during the normal operation of the circuit, that means ...
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130 views

ultrasonic-sensor to Logic Level Converter to raspberry pi

Trying to connect Ultrasonic sensor to my raspberry Pi. Im aware of two methods: connect the trig to a 1k resister before connecting to raspberry pi Use a 8-Channel Logic level converter I trying ...
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58 views

Logic level shifting

I want to interface 12 VDC rated WS2815B addressable LED strip with a 3.3 VDC microcontroller. I am having difficulty finding a logic level shifter which translates 3.3 V to 12 V. Data rate is ...
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388 views

Logic-level converter FET

I have been using the BSS138 level converter circuit for a while now and today it struck me I get how the voltage is stepped up by the FET or the BSS138 when you are applying say 3.3 V on the LV side. ...
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38 views

trigger a circuit using one time signal

I'm really new to electronics and I need help. Say I have Line A. I need to control Line A to set it as HIGH or LOW using a one time signal through one input line X or maximum through two lines X and ...
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62 views

Question regarding MCU, Voltages and Level Shifting

I have a board with a 3.3v MCU (C8051F850 from Silicon Labs in a QSOP-24 package) but whose pins are 5v tolerant. The board is running at 5v and all the relevant GPIO pins from Ports 0 & 1 have ...
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3answers
300 views

When to choose active-low over active-high for a switch?

I was reading this intro article: https://learn.sparkfun.com/tutorials/logic-levels/all#active-low-and-active-high Is there a particular time when an active low signal is preferred over an active ...
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46 views

Can I use TXB0104B bidirectional level shifters on the Intel 8085 NMOS CPU buses?

I want to connect an old Intel 8085 CPU to an FPGA board. The basic issue is that the 8085 works at 5V while the FPGA will not accept any voltage avobe 3.3V so I decided to use the TXB0104 / TXB0108 ...
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2answers
142 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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516 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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82 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
233 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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157 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
124 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
453 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
144 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
429 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
202 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
96 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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132 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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35 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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72 views

state of a transistor when Vc>Vb=Ve

what is the state of Q7 and Q8, on or off, when both inputs are low? their base and emitter voltages are equal I think but collector voltages seems a bit higher since there is no diode on its way to ...
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3answers
2k 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 ...
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1answer
235 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
58 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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491 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
452 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 ...