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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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High Frequency Logic Level Conversion

I am using Arduino DUE for my project which gives a 3.3 volt output signal. I have to convert it to 5 volts to use it with another device. The problem is that my signal frequency is 1 MHz. I have ...
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2answers
568 views

Logic low not low enough

I'm having an issue where the "low" level being output from one device isn't low enough for the device on the other end to interpret it as such. I'm guessing I'm not the first person to have this ...
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2answers
780 views

Digital out, output low voltage, no load

I'm controlling a home-built current regulator, using a PIC microcontroller (PIC12F1572). The regulator is implemented using an op-amp and mosfet, and works well. The input to the regulator is a ...
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How do you choose a diode for a 5v to 3.3v clamping circuit

I have a logic input that is 3.3v and I want to be able to allow it to interface with either 3.3v or 5v input signals w/o worrying about it being damaged. I would like to use a resistor with a ...
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3answers
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Circuit to switch about 5W of 12V using CMOS logic inputs using N-channel MOSFET?

I want to switch some 12V landscape light LEDs, totaling about 5 watts, using MOSFETs, with the control signal provided by a digital output line from an Arduino microcontroller running at 5V. I ...
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3answers
4k views

Low power serial bluetooth module with Arduino

I plan to use the HC-06 serial bluetooth module with an Arduino Leonardo. To my knowledge, the Arduino's serial pins output at 5V with 40mA of current. The HC-06's datasheet says it will accept input ...
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1answer
94 views

Connecting separately powered devices via serial

I have a small issue connecting an FTDI USB to 5V Serial adapter to an externally powered PIC microcontroller. They are connected via serial connection. The USB connection powered the FTDI and a ...
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2answers
86 views

Where to look for logic level of a circuit in the datasheet?

Whenever I pick a chip for my project, I run through the same chore: finding out if its logic levels match what I work with. Is it 5V? 3.3V? 1.3V? Or one of these that sources whatever level I apply ...
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1answer
740 views

Is it safe to use a bus buffer as level shifter?

I am currently using SN74ABT5402ADW as a buffer and level shifter for my ADC, however, the datasheet does not explicitly say that it can be used as a level shifter. I provide it with 5V power, but the ...
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3k views

Should I use CMOS vs. TTL?

Now, I know that this question has been asked so many times that it seems like I'm trolling, but I must point out that I couldn't find the right answer to this question anywhere. So yeah, CMOS and ...
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2answers
3k views

Fan in Fan out problem

Fan out is the maximum number of inputs that can be connected to a specific output. Why can’t we connect more number of inputs to this output?
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3answers
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CD40xx and SN74xx logic gates not working correctly

So, a few weeks ago I got into digital logic, and thought I'd buy some logic ICs. However, instead of doing actual research about which ones are good and which ones are bad, I just bought whichever ...
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3answers
2k views

How do I invert a signal without deforming it, and without using a logic gate?

I have an IC which outputs pulses over an open collector pin. I need both these pulses and their inverses in my circuit. I want to do the inversion by using as few as possible transistors and without ...
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2answers
157 views

Couple questions about logic levels

I have a microcontroller (ATmega328) that runs on 5V and another chip (MAX31855), connected via SPI as a slave (that only using the MISO line), that runs on 3.3V. Do I need to convert the output of ...
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1answer
2k views

BSS138 levelshifter draws 35-40mA current when one side is grounded?

I completely rewrote my question as I found the source of the issue is related to the level shifter only. This is the circuit for a 3.3V to 5V bidirectional levelshifter, used frequently. My ...
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2answers
1k views

How to avoid short circuit when connecting a microcontroller and device using I2C bus?

I am attempting to connect an 8051-compatible microcontroller to an accelerometer using the I2C bus. Both devices operate at the same voltage, 3.3v. However, I am failing to understand something: won'...
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3answers
4k views

3V3 to 5V level conversion

I'm currently working on the development of some measurement equipment. For conversions I use a small ARM which runs on 3V3 and to display the results I use a graphical display running on 5V. This ...
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1answer
2k views

Arduino <-> BBB UART issues using bi-directional level converter (5v to 3.3v)

I am having a strange issue interfacing between an Arduino and BeagleBoneBlack over UART. The Arduino is 5v logic, and the BBB is 3.3v logic, so I'm using a bi-directional logic level converter from ...
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1answer
189 views

making sense of HCT ACT cmos “addional supply current”

I'm trying to make a low-current level shifter from low voltage (~2V) CMOS up to 5V CMOS. I had the idea to use TTL-compatible CMOS gates in the HCT or ACT families. But this line in the 74HCT04 ...
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3answers
187 views

Sniffing a proprietary data line at 47.5V

I need to sniff the physical layer of a proprietary data line with a logic analyser, but my analyser is limited to 5V input. Unfortunately the line runs at 47.5V, which would fry everything. I ...
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9answers
52k views

Is there any bidirectional 5v-3.3v level shifter?

Is there any IC that interfaces any 3.3V Input/Output to 5V Output/Input? I need it primarily for an Arduino Due but if there any bidirectional IC that works like that it would be great. Some people ...
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2answers
3k views

Control relay from sensor output when LOW is 0.2V

I used this circuit as a reference to drive a relay from the digital output of an arduino. This circuit worked as expected. simulate this circuit – Schematic created using CircuitLab ...
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1answer
72 views

GPIO pull up to different level

I am using MSP430F235 which is supplied with 2.5V on DVCC. So, all its I/Os will be in 2.5V level. Now, I want to enable a LDO in which EN pin is tied to a different level (>2.5V is the battery supply ...
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3answers
515 views

Logic level converter for H-bridge and UART for Raspberry Pi

Here is my situation: I'm using a raspberry Pi to control a H-Bridge. The H-Bridge is not tolerant of both it's inputs being high logic value, which causes a short through the transistors, bypassing ...
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1answer
2k views

Is PIC running at 3.3v, 5V logic tolerant?

Can a micro-controller that is capable of running at voltages ranging from 2.3 to 5.5 V, tolerate 5V logic levels while operating at 3.3V? I need to interface GPS (5V) and raspberry Pi (3.3V) with my ...
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1answer
2k views

Converting 3.3v logic level to 5v using octal bus transceiver

I'm using the Raspberry PI to communicate with various sensors and other circuits that input and output 5V logic level. The Raspberry Pi itself has 3.3V GPIOs, so i need to convert the logic levels. ...
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1answer
1k views

TTL logical low isn't ground

I'm working with an Arduino Due and four 5V TTL pressure sensors. I'm using this logic level converter to convert from the 3.3V Due to the 5V sensors. I've been having problems using all four at a ...
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2answers
51k views

Single transistor level up shifter

I need a simple, single directionnal level shifter for 3.3V -> 5V conversion. There are many options on the internet, some using a logic ic and some using 2 NPN transistors (converter and inverter), ...
35
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1answer
121k views

Step up 3.3V to 5V for digital I/O

I normally use an Arduino for my projects because it has 5V inputs and outputs and has 5V Vin so that makes life very easy when interfacing with 5V components. For this project I want to use a ...
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2answers
5k views

GY-521 MPU-6050 + Arduino nano - Logic converter or not?

I bought this MPU-6050: link (marked as "GY-521" on the board) According to the manufacturers' site, the sensor logic level is 3.3V (though the eBay page says ...
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1answer
368 views

Is the logic level of a MCU the same as the operating voltage?

The Atmega328 has an operating voltage of 1.8V to 5.5V. If I was operating it at 3V (by supplying 3V to VCC) and set a pin to high, would that pin be at 3V?
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1answer
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Sensing 12v inputs in 3.3v system

Sorry if this has been asked before, but I searched for a while and didn't find anything that exactly answered my question. I would like to sense the "dummy lights"(oil, neutral, etc.) in my ...
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1answer
2k views

Detect logic signal in a long distance. What type of interface to use?

My daughter board uses a comparator(LM339) to output logic 1 or 0 under a 3v3 supply. The cable connecting daughter board and main board is at least 1.5m. Luckily, the frequency is not fast but the ...
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1answer
745 views

multiply binary numbers [closed]

Is it any book which explains how to multiply binary numbers and how to create appropriate digital circuit schema?(i.e. digital schema which compute the multiplication of the binary numbers).
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2answers
575 views

Translating to “below ground” logic levels

I have an RF switch chip that is controlled by a logic signal with levels of 0 V and -3 V. I want to control this from a CPLD that's producing ordinary +3.3 V CMOS levels. Board area is at a premium ...
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3answers
7k views

controlling SPI devices using the Arduino - different voltages

My arduino board uses 5v to power the atmega chip. I was wondering is there any thing wrong with powering my atmega at 5v but say I power my MCP4922 dac at 3.3v does it matter? It just that I've seen ...
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3answers
541 views

Connecting 3.3 and 5 V devices

The requirements are different from similar questions I've found here. TXB/TXS are expensive for my needs. Sparkfun's logic shifter is bi-directional, while I need two uni-directional conversions, <...
4
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1answer
3k views

What is the difference between a voltage-level translator and a logic-level translator?

(This is a follow-up to an earlier question of mine.) I would like to use the GTL2000 bi-directional translator IC to facilitate level translation between a 3.3V circuit and a 5V circuit (including ...
4
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2answers
904 views

Interfacing 3V TI MSP430 to PC serial port

I am scratching my head to figure out a possible soloution for this scenario: I am developing a simple application using TI MSP430 microcontroller. The microcontrol part is powered by 2xAA batteries. ...
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1answer
115 views

what are cores in real in a cpu?

i would like to know what cores at physical level are in a cpu. some mix of logic gates make a head that's called a core is it?.so one core how does it appear to be in physical level.! PLease am new ...
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2answers
4k views

Logic Levels between 5(V) and 3.3(V) devices

I am using a 5V microcontroller to communicate with a Bluetooth module operating at 3.3V. I have regulated the output from the 5V microcontroller rail to 3.3V rail for the Bluetooth module. Since I ...
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4answers
3k views

Using an open-collector output from one IC to trigger a level change on the input pin of another IC?

So my problem is simple: I have an IC that provides an output pin to alert you when some condition is met. The output pin is open-collector, high-impedance when active. I want to monitor this output ...
5
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1answer
171 views

Need 1-4 pins controlling 16pins logic level

I have max four outputs coming from a PIC. I need these four outputs (or one serially) to simultaneously control 16 pins with a logic level. This is for a clock application. A BCD could accomplish ...
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2answers
2k views

Methods to drive a multiplexed LCD with logic-level signals?

I've used such a technique in a couple of the products I've designed, but I've never seen anyone else do so. It's possible to drive a 3-way multiplexed LCD using a bunch of 74HC595's to generate an 8-...