LED on same Pin as Toggle Switch, not illuminatinghow to calculate correct resistor value to use with LEDs...
TGV timetables / schedules?
How do we improve the relationship with a client software team that performs poorly and is becoming less collaborative?
A newer friend of my brother's gave him a load of baseball cards that are supposedly extremely valuable. Is this a scam?
Why has Russell's definition of numbers using equivalence classes been finally abandoned? ( If it has actually been abandoned).
Why can't I see bouncing of a switch on an oscilloscope?
Why is this code 6.5x slower with optimizations enabled?
Draw simple lines in Inkscape
What are these boxed doors outside store fronts in New York?
How does one intimidate enemies without having the capacity for violence?
Is it possible to do 50 km distance without any previous training?
What is the offset in a seaplane's hull?
How is it possible for user's password to be changed after storage was encrypted? (on OS X, Android)
If Manufacturer spice model and Datasheet give different values which should I use?
Why was the small council so happy for Tyrion to become the Master of Coin?
How can I fix this gap between bookcases I made?
Are tax years 2016 & 2017 back taxes deductible for tax year 2018?
Email Account under attack (really) - anything I can do?
"which" command doesn't work / path of Safari?
What makes Graph invariants so useful/important?
Accidentally leaked the solution to an assignment, what to do now? (I'm the prof)
Why are 150k or 200k jobs considered good when there are 300k+ births a month?
How old can references or sources in a thesis be?
How is this relation reflexive?
Are white and non-white police officers equally likely to kill black suspects?
LED on same Pin as Toggle Switch, not illuminating
how to calculate correct resistor value to use with LEDs Potentiometer and other devices?Source power with 2 V and LED with forward voltage of 2 V7-Segment Common AnodeConnecting a switch and a MOSFET to an Arduino?Multi-LED Toggle SwitchWhy adding a LED between Pin 3 and Ground causes LCD display not to show text?Getting more current through an LED arraydigitalRead not reading input pin of ESP8266-01Yellow LED got burned, green LED didn'tProblem : Trigger limit switch to stop DC motor
I am trying to do something I think should be relatively simple. I would like to read an input from a toggle switch, and have a red 5mm LED indicate the state of the switch. Rather, however, than have an input for the switch and an output for the LED (controlled by software), I'd like to put them in series on a single circuit. That is, flip the toggle and current flows from the 5v source on the Arduino Uno through an LED and to an input pin on the Arduino. (I would ultimately like to have eight such switches; I am trying to create a sort of simulated byte, with individually flippable bits controlled by toggles; this will be read by a GTK Python program, that can interpret that "byte" in different ways: as a decimal value, a hex value, an ASCII character, a color in 8-bit color space, etc).
So, I have an LED with a 200 Ohm current-limiting resistor. I also have a pull-down resistor (1k) to prevent the toggle from floating.
My results, however, have been inconsistent. Using a breadboard, I've gotten this working. But it seems very fragile, and sometimes when I rebuild the circuit on a breadboard, it doesn't work as expected. Right now, for instance, the switch seems to work, and I am reading the expected value from the Serial Monitor--but the LED is not illuminating.
I had been playing around with different values for the pull-down resistor and the current-limiting resistor. This pair (200-ohm current limiting; 1k pull down) seemed to work, but now isn't. (I have swapped out the LED; and current is passing through the LED, otherwise I wouldn't be able to read the correct pin value--I think.)
Is there something I'm not understanding? Does the position of the current limiting resistor (before/after the LED) make any difference (I assume not)? Does this seem like the correct setup for what I'm trying to achieve? More generally, should, in principle, this approach scale to 8 more toggle/LED pairs? Is there a better/smarter approach? Is there a reason why I see so few Arduino projects that put LEDs in series with an input toggle?
The breadboard looks like this:
arduino-uno led switch
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I am trying to do something I think should be relatively simple. I would like to read an input from a toggle switch, and have a red 5mm LED indicate the state of the switch. Rather, however, than have an input for the switch and an output for the LED (controlled by software), I'd like to put them in series on a single circuit. That is, flip the toggle and current flows from the 5v source on the Arduino Uno through an LED and to an input pin on the Arduino. (I would ultimately like to have eight such switches; I am trying to create a sort of simulated byte, with individually flippable bits controlled by toggles; this will be read by a GTK Python program, that can interpret that "byte" in different ways: as a decimal value, a hex value, an ASCII character, a color in 8-bit color space, etc).
So, I have an LED with a 200 Ohm current-limiting resistor. I also have a pull-down resistor (1k) to prevent the toggle from floating.
My results, however, have been inconsistent. Using a breadboard, I've gotten this working. But it seems very fragile, and sometimes when I rebuild the circuit on a breadboard, it doesn't work as expected. Right now, for instance, the switch seems to work, and I am reading the expected value from the Serial Monitor--but the LED is not illuminating.
I had been playing around with different values for the pull-down resistor and the current-limiting resistor. This pair (200-ohm current limiting; 1k pull down) seemed to work, but now isn't. (I have swapped out the LED; and current is passing through the LED, otherwise I wouldn't be able to read the correct pin value--I think.)
Is there something I'm not understanding? Does the position of the current limiting resistor (before/after the LED) make any difference (I assume not)? Does this seem like the correct setup for what I'm trying to achieve? More generally, should, in principle, this approach scale to 8 more toggle/LED pairs? Is there a better/smarter approach? Is there a reason why I see so few Arduino projects that put LEDs in series with an input toggle?
The breadboard looks like this:
arduino-uno led switch
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago
add a comment |
I am trying to do something I think should be relatively simple. I would like to read an input from a toggle switch, and have a red 5mm LED indicate the state of the switch. Rather, however, than have an input for the switch and an output for the LED (controlled by software), I'd like to put them in series on a single circuit. That is, flip the toggle and current flows from the 5v source on the Arduino Uno through an LED and to an input pin on the Arduino. (I would ultimately like to have eight such switches; I am trying to create a sort of simulated byte, with individually flippable bits controlled by toggles; this will be read by a GTK Python program, that can interpret that "byte" in different ways: as a decimal value, a hex value, an ASCII character, a color in 8-bit color space, etc).
So, I have an LED with a 200 Ohm current-limiting resistor. I also have a pull-down resistor (1k) to prevent the toggle from floating.
My results, however, have been inconsistent. Using a breadboard, I've gotten this working. But it seems very fragile, and sometimes when I rebuild the circuit on a breadboard, it doesn't work as expected. Right now, for instance, the switch seems to work, and I am reading the expected value from the Serial Monitor--but the LED is not illuminating.
I had been playing around with different values for the pull-down resistor and the current-limiting resistor. This pair (200-ohm current limiting; 1k pull down) seemed to work, but now isn't. (I have swapped out the LED; and current is passing through the LED, otherwise I wouldn't be able to read the correct pin value--I think.)
Is there something I'm not understanding? Does the position of the current limiting resistor (before/after the LED) make any difference (I assume not)? Does this seem like the correct setup for what I'm trying to achieve? More generally, should, in principle, this approach scale to 8 more toggle/LED pairs? Is there a better/smarter approach? Is there a reason why I see so few Arduino projects that put LEDs in series with an input toggle?
The breadboard looks like this:
arduino-uno led switch
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I am trying to do something I think should be relatively simple. I would like to read an input from a toggle switch, and have a red 5mm LED indicate the state of the switch. Rather, however, than have an input for the switch and an output for the LED (controlled by software), I'd like to put them in series on a single circuit. That is, flip the toggle and current flows from the 5v source on the Arduino Uno through an LED and to an input pin on the Arduino. (I would ultimately like to have eight such switches; I am trying to create a sort of simulated byte, with individually flippable bits controlled by toggles; this will be read by a GTK Python program, that can interpret that "byte" in different ways: as a decimal value, a hex value, an ASCII character, a color in 8-bit color space, etc).
So, I have an LED with a 200 Ohm current-limiting resistor. I also have a pull-down resistor (1k) to prevent the toggle from floating.
My results, however, have been inconsistent. Using a breadboard, I've gotten this working. But it seems very fragile, and sometimes when I rebuild the circuit on a breadboard, it doesn't work as expected. Right now, for instance, the switch seems to work, and I am reading the expected value from the Serial Monitor--but the LED is not illuminating.
I had been playing around with different values for the pull-down resistor and the current-limiting resistor. This pair (200-ohm current limiting; 1k pull down) seemed to work, but now isn't. (I have swapped out the LED; and current is passing through the LED, otherwise I wouldn't be able to read the correct pin value--I think.)
Is there something I'm not understanding? Does the position of the current limiting resistor (before/after the LED) make any difference (I assume not)? Does this seem like the correct setup for what I'm trying to achieve? More generally, should, in principle, this approach scale to 8 more toggle/LED pairs? Is there a better/smarter approach? Is there a reason why I see so few Arduino projects that put LEDs in series with an input toggle?
The breadboard looks like this:
arduino-uno led switch
arduino-uno led switch
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 6 hours ago
cforstercforster
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 6 hours ago
cforstercforster
1031
asked 6 hours ago
cforstercforster
1031
1031
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
cforster is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago
add a comment |
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago
add a comment |
1 Answer
1
active
oldest
votes
LEDs have a (fairly) fixed voltage drop across them. The red LED is about 2V.
You can use that to work out the voltage at the input. You basically have a voltage divider, with your 200Ω resistor as R1, and your 1kΩ resistor as R2. The voltage drop of the diode is subtracted from Vin.
So:
Vout = (Vin - Vled) * (R2 / (R1 + R2))
= (5 - 2) * (1000 / (200 + 1000))
= 3 * (1000 / 1200)
= 3 * 0.833
= 2.5V
The ATMega328P datasheet states that a HIGH input voltage must be over 0.6*Vcc, and a LOW input voltage must be below 0.3*Vcc. That means to register a HIGH you need more than 3V. To register a LOW you need less than 1.5V.
You're between those two voltages - in the "dead zone".
The simplest way to achieve what you want is to use a douple-pole switch and keep the LED completely separate from the Arduino.
answered 6 hours ago
Majenko♦Majenko
69.4k43277
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("schematics", function () {
StackExchange.schematics.init();
});
}, "cicuitlab");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "540"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
cforster is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2farduino.stackexchange.com%2fquestions%2f63273%2fled-on-same-pin-as-toggle-switch-not-illuminating%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
LEDs have a (fairly) fixed voltage drop across them. The red LED is about 2V.
You can use that to work out the voltage at the input. You basically have a voltage divider, with your 200Ω resistor as R1, and your 1kΩ resistor as R2. The voltage drop of the diode is subtracted from Vin.
So:
Vout = (Vin - Vled) * (R2 / (R1 + R2))
= (5 - 2) * (1000 / (200 + 1000))
= 3 * (1000 / 1200)
= 3 * 0.833
= 2.5V
The ATMega328P datasheet states that a HIGH input voltage must be over 0.6*Vcc, and a LOW input voltage must be below 0.3*Vcc. That means to register a HIGH you need more than 3V. To register a LOW you need less than 1.5V.
You're between those two voltages - in the "dead zone".
The simplest way to achieve what you want is to use a douple-pole switch and keep the LED completely separate from the Arduino.
answered 6 hours ago
Majenko♦Majenko
69.4k43277
add a comment |
LEDs have a (fairly) fixed voltage drop across them. The red LED is about 2V.
You can use that to work out the voltage at the input. You basically have a voltage divider, with your 200Ω resistor as R1, and your 1kΩ resistor as R2. The voltage drop of the diode is subtracted from Vin.
So:
Vout = (Vin - Vled) * (R2 / (R1 + R2))
= (5 - 2) * (1000 / (200 + 1000))
= 3 * (1000 / 1200)
= 3 * 0.833
= 2.5V
The ATMega328P datasheet states that a HIGH input voltage must be over 0.6*Vcc, and a LOW input voltage must be below 0.3*Vcc. That means to register a HIGH you need more than 3V. To register a LOW you need less than 1.5V.
You're between those two voltages - in the "dead zone".
The simplest way to achieve what you want is to use a douple-pole switch and keep the LED completely separate from the Arduino.
answered 6 hours ago
Majenko♦Majenko
69.4k43277
add a comment |
LEDs have a (fairly) fixed voltage drop across them. The red LED is about 2V.
You can use that to work out the voltage at the input. You basically have a voltage divider, with your 200Ω resistor as R1, and your 1kΩ resistor as R2. The voltage drop of the diode is subtracted from Vin.
So:
Vout = (Vin - Vled) * (R2 / (R1 + R2))
= (5 - 2) * (1000 / (200 + 1000))
= 3 * (1000 / 1200)
= 3 * 0.833
= 2.5V
The ATMega328P datasheet states that a HIGH input voltage must be over 0.6*Vcc, and a LOW input voltage must be below 0.3*Vcc. That means to register a HIGH you need more than 3V. To register a LOW you need less than 1.5V.
You're between those two voltages - in the "dead zone".
The simplest way to achieve what you want is to use a douple-pole switch and keep the LED completely separate from the Arduino.
answered 6 hours ago
Majenko♦Majenko
69.4k43277
LEDs have a (fairly) fixed voltage drop across them. The red LED is about 2V.
You can use that to work out the voltage at the input. You basically have a voltage divider, with your 200Ω resistor as R1, and your 1kΩ resistor as R2. The voltage drop of the diode is subtracted from Vin.
So:
Vout = (Vin - Vled) * (R2 / (R1 + R2))
= (5 - 2) * (1000 / (200 + 1000))
= 3 * (1000 / 1200)
= 3 * 0.833
= 2.5V
The ATMega328P datasheet states that a HIGH input voltage must be over 0.6*Vcc, and a LOW input voltage must be below 0.3*Vcc. That means to register a HIGH you need more than 3V. To register a LOW you need less than 1.5V.
You're between those two voltages - in the "dead zone".
The simplest way to achieve what you want is to use a douple-pole switch and keep the LED completely separate from the Arduino.
answered 6 hours ago
Majenko♦Majenko
69.4k43277
answered 6 hours ago
Majenko♦Majenko
69.4k43277
answered 6 hours ago
Majenko♦Majenko
69.4k43277
answered 6 hours ago
Majenko♦Majenko
69.4k43277
69.4k43277
add a comment |
add a comment |
cforster is a new contributor. Be nice, and check out our Code of Conduct.
cforster is a new contributor. Be nice, and check out our Code of Conduct.
cforster is a new contributor. Be nice, and check out our Code of Conduct.
cforster is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Arduino Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2farduino.stackexchange.com%2fquestions%2f63273%2fled-on-same-pin-as-toggle-switch-not-illuminating%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Do you want to turn the led on and off regardless of the switch as well? Or do you only want to read the switch (and the switch turns the led on and off).
– Jot
3 hours ago