LED on same Pin as Toggle Switch, not illuminatinghow to calculate correct resistor value to use with LEDs...
I see my dog run
How do you conduct xenoanthropology after first contact?
How to report a triplet of septets in NMR tabulation?
Japan - Plan around max visa duration
Are tax years 2016 & 2017 back taxes deductible for tax year 2018?
What is the offset in a seaplane's hull?
Can an x86 CPU running in real mode be considered to be basically an 8086 CPU?
How is the claim "I am in New York only if I am in America" the same as "If I am in New York, then I am in America?
Why CLRS example on residual networks does not follows its formula?
What do you call something that goes against the spirit of the law, but is legal when interpreting the law to the letter?
Is there really no realistic way for a skeleton monster to move around without magic?
The use of multiple foreign keys on same column in SQL Server
A function which translates a sentence to title-case
Can I make popcorn with any corn?
How can I fix this gap between bookcases I made?
Is there a minimum number of transactions in a block?
How can the DM most effectively choose 1 out of an odd number of players to be targeted by an attack or effect?
Is Social Media Science Fiction?
Chess with symmetric move-square
Can a German sentence have two subjects?
Why can't I see bouncing of a switch on an oscilloscope?
Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground?
Could a US political party gain complete control over the government by removing checks & balances?
Infinite past with a beginning?
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
New contributor
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
New contributor
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
New contributor
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
New contributor
New contributor
New contributor
asked 6 hours ago
cforstercforster
1033
1033
New contributor
New contributor
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.
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
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.
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
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.
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
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.
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
69.4k43277
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
add a comment |
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
Using a double-pole switch seems indeed the smarter approach here. Thanks. I see your logic... but it doesn't account for my case, however, where I am getting the correct input on the Arduino--the LED is not illuminating. The dead zone you note would be like a floating pin, no?
– cforster
17 mins ago
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