I wrote a code for determining the push button state wheather it's long pressed or not. By the way this function is called by a timer interrupt routine in every 1 ms.
If you pressed more than 1 second, LongPressed is active ShortPressed is passive .so vice versa.
1- But it seems really dummy how can I make it shorter and more efficient according to both readibilty and professional rules?
BTW I updated the code like below.
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
/*button pressed and count*/
if(!HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_13))
{
usTick++;
}
/*not pressed*/
else
{
if( usTick > 1000){
ButtonState.PressedState = LongPressed;
HAL_GPIO_TogglePin(GPIOA,GPIO_PIN_5);
usTick = 0;
}
else if( usTick >350){
ButtonState.PressedState = ShortPressed;
HAL_GPIO_TogglePin(GPIOA,GPIO_PIN_5);
usTick = 0;
}
usTick = 0;
}
}
2- What should I add or change to get double Tap pressing information in this updated code?
Almost every STM32 timer has "external trigger synchronization" function. You can read about it in timer functional description in reference manual. You can use "Slave mode: Trigger mode" to start counting on "button down" event. And in EXTI interrupt of "button up event" you can read timer counter and do your business.
I don't know how to implement this via HAL, but Standard Peripheral Library should have the example.
1) Your code is only able to handle 1 button. Make it object oriented to read n buttons.
1 ms is much too fast. 20 ms should work fine. Remember: humans are slow.
2) I once had spent some time creating a LED controller with two pushbutton rotary encoders. These would feature advanced programming methods by means of pushing them long or multiple times. You could use the result of my sparring (it was never completed) as inspiration. The button code is fairly complex, it should fulfill your needs. And I remember it to be functional.
https://github.com/Jeroen6/LED-Rotary-Dimmer-SW/blob/master/user/button.c
https://github.com/Jeroen6/LED-Rotary-Dimmer-SW/blob/master/user/button.h
Forgive me for not having the indentations worked out correctly.
Related
I came across this code by Ganssle regarding switch debouncing. The code seems pretty efficient, and the few questions I have maybe very obvious, but I would appreciate clarification.
Why does he check 10 msec for button press and 100 msec for button release. Can't he just check 10 msec for press and release?
Is polling this function every 5 msec from main the most effecient way to execute it or should I check for an interrupt in the pin and when there is a interrupt change the pin to GPI and go into the polling routine and after we deduce the value switch the pin back to interrupt mode?
#define CHECK_MSEC 5 // Read hardware every 5 msec
#define PRESS_MSEC 10 // Stable time before registering pressed
#define RELEASE_MSEC 100 // Stable time before registering released
// This function reads the key state from the hardware.
extern bool_t RawKeyPressed();
// This holds the debounced state of the key.
bool_t DebouncedKeyPress = false;
// Service routine called every CHECK_MSEC to
// debounce both edges
void DebounceSwitch1(bool_t *Key_changed, bool_t *Key_pressed)
{
static uint8_t Count = RELEASE_MSEC / CHECK_MSEC;
bool_t RawState;
*Key_changed = false;
*Key_pressed = DebouncedKeyPress;
RawState = RawKeyPressed();
if (RawState == DebouncedKeyPress) {
// Set the timer which will allow a change from the current state.
if (DebouncedKeyPress) Count = RELEASE_MSEC / CHECK_MSEC;
else Count = PRESS_MSEC / CHECK_MSEC;
} else {
// Key has changed - wait for new state to become stable.
if (--Count == 0) {
// Timer expired - accept the change.
DebouncedKeyPress = RawState;
*Key_changed=true;
*Key_pressed=DebouncedKeyPress;
// And reset the timer.
if (DebouncedKeyPress) Count = RELEASE_MSEC / CHECK_MSEC;
else Count = PRESS_MSEC / CHECK_MSEC;
}
}
}
Why does he check 10 msec for button press and 100 msec for button release.
As the blog post says, "Respond instantly to user input." and "A 100ms delay is quite noticeable".
So, the main reason seems to be to emphasize that the make-debounce should be kept short so that the make is registered "immediately" by human sense, and that the break debounce is less time sensitive.
This is also supported by a paragraph near the end of the post: "As I described in the April issue, most switches seem to exhibit bounce rates under 10ms. Coupled with my observation that a 50ms response seems instantaneous, it's reasonable to pick a debounce period in the 20 to 50ms range."
In other words, the code in the example is much more important than the example values, and that the proper values to be used depends on the switches used; you're supposed to decide those yourself, based on the particulars of your specific use case.
Can't he just check 10 msec for press and release?
Sure, why not? As he wrote, it should work, even though he wrote (as quoted above) that he prefers a bit longer debounce periods (20 to 50 ms).
Is polling this function every 5 msec from main the most effecient way to execute it
No. As the author wrote, "All of these algorithms assume a timer or other periodic call that invokes the debouncer." In other words, this is just one way to implement software debouncing, and the shown examples are based on a regular timer interrupt, that's all.
Also, there is nothing magical about the 5 ms; as the author says, "For quick response and relatively low computational overhead I prefer a tick rate of a handful of milliseconds. One to five milliseconds is ideal."
or should I check for an interrupt in the pin and when there is a interrupt change the pin to GPI and go into the polling routine and after we deduce the value switch the pin back to interrupt mode?
If you implement that in code, you'll find that it is rather nasty to have an interrupt that blocks the normal running of the code for 10 - 50ms at a time. It is okay if checking the input pin state is the only thing being done, but if the hardware does anything else, like update a display, or flicker some blinkenlights, your debouncing routine in the interrupt handler will cause noticeable jitter/stutter. In other words, what you suggest, is not a practical implementation.
The way the periodic timer interrupt based software debouncing routines (shown in the original blog post, and elsewhere) work, they take only a very short amount of time, just a couple of dozen cycles or so, and do not interrupt other code for any significant amount of time. This is simple, and practical.
You can combine a periodic timer interrupt and an input pin (state change) interrupt, but since the overhead of many of the timer-interrupt-only -based software debounces is tiny, it typically is not worth the effort trying to combine the two -- the code gets very, very complicated, and complicated code (especially on an embedded device) tends to be hard/expensive to maintain.
The only case I can think of (but I'm only a hobbyist, not an EE by any means!) is if you wanted to minimize power use for e.g. battery powered operation, and used the input pin interrupt to bring the device to partial or full power mode from sleep, or similar.
(Actually, if you also have a millisecond or sub-millisecond counter (not necessarily based on an interrupt, but possibly a cycle counter or similar), you can use the input pin interrupt and the cycle counter to update the input state on the first change, then desensitize it for a specific duration afterwards, by storing the cycle counter value at the state change. You do need to handle counter overflow, though, to avoid the situation where a long ago event seems to have happened just a short time ago, due to counter overflowing.)
I found Lundin's answer quite informative, and decided to edit my answer to show my own suggestion for software debouncing. This might be especially interesting if you have very limited RAM, but lots of buttons multiplexed, and you want to be able to respond to key presses and releases with minimum delay.
Do note that I do not wish to imply this is "best" in any sense of the world; I only want you to show one approach I haven't seen often used, but which might have some useful properties in some use cases. Here, too, the number of scan cycles (milliseconds) the input changes are ignored (10 for make/off-to-ON, 10 for break/on-to-OFF) are just example values; use an oscilloscope or trial-and-error to find the best values in your use case. If this is an approach you find more suitable to your use case than the other myriad alternatives, that is.
The idea is simple: use a single byte per button to record the state, with the least significant bit describing the state, and the seven other bits being the desensitivity (debounce duration) counter. Whenever a state change occurs, the next change is only considered a number of scan cycles later.
This has the benefit of responding to changes immediately. It also allows different make-debounce and break-debounce durations (during which the pin state is not checked).
The downside is that if your switches/inputs have any glitches (misreadings outside the debounce duration), they show up as clear make/break events.
First, you define the number of scans the inputs are desensitized after a break, and after a make. These range from 0 to 127, inclusive. The exact values you use depend entirely on your use case; these are just placeholders.
#define ON_ATLEAST 10 /* 0 to 127, inclusive */
#define OFF_ATLEAST 10 /* 0 to 127, inclusive */
For each button, you have one byte of state, variable state below; initialized to 0. Let's say (PORT & BIT) is the expression you use to test that particular input pin, evaluating to true (nonzero) for ON, and false (zero) for OFF. During each scan (in your timer interrupt), you do
if (state > 1)
state -= 2;
else
if ( (!(PORT & BIT)) != (!state) ) {
if (state)
state = OFF_ATLEAST*2 + 0;
else
state = ON_ATLEAST*2 + 1;
}
At any point, you can test the button state using (state & 1). It will be 0 for OFF, and 1 for ON. Furthermore, if (state > 1), then this button was recently turned ON (if state & 1) or OFF (if state & 0) and is therefore not sensitive to changes in the input pin state.
In addition to the accepted answer, if you just wish to poll a switch from somewhere every n ms, there is no need for all of the obfuscation and complexity from that article. Simply do this:
static bool prev=false;
...
/*** execute every n ms ***/
bool btn_pressed = (PORT & button_mask) != 0;
bool reliable = btn_pressed==prev;
prev = btn_pressed;
if(!reliable)
{
btn_pressed = false; // btn_pressed is not yet reliable, treat as not pressed
}
// <-- here btn_pressed contains the state of the switch, do something with it
This is the simplest way to de-bounce a switch. For mission-critical applications, you can use the very same code but add a simple median filter for the 3 or 5 last samples.
As noted in the article, the electro-mechanical bounce of switches is most often less than 10ms. You can easily measure the bouncing with an oscilloscope, by connecting the switch between any DC supply and ground (in series with a current-limiting resistor, preferably).
Arduino Nano and I need a timer within a timer and having some problems getting my head around the logic. I have played with some Libraries on GitHub, Timer, SimpleTimer and Metro but none seem to do what I need. Or, if they can I can't seem to get them to do it.
I need to switch a relay on for about 2-minutes and then off, every hour. I am trying
loop
{ if (millis() - 3600000 > TimeMax)
{ relay(on);
if (millis() - 12000 > relayMax)
TimeMax = millis();
}
}
It doesn't seem to work and I need this to all stay working within the "loop" as I have an nRF24L radio listening.
Could someone please help me with code snippets or at least an outline how to go about this.
Thanks
Ok, first of all timers in embedded dev speak means interrupts that gets fired after a delay. Generally speaking you want interrupts to handle very atomic actions, because you don't want to have an interrupt triggered while another one is triggered, because that could be the scenario of a horror movie.
But why would you want to make something hard, complex and overengineered, when it can be simple?
All you need to do is handle it through a simple dual state machine:
#define OPEN_DELAY 120*1000
#define CLOSE_DELAY 3600*1000
// N.B.: to be precise here, to make 2 minutes every hour,
// CLOSE_DELAY should be 3600*1000-OPEN_DELAY so it
// does not shift by 2 minutes every hour.
void loop() {
static bool open=false;
static long timestamp = millis();
if (!open && millis()-timestamp > CLOSE_DELAY) {
open=true; // change state
timestamp = millis(); // rearm timestamp
set_relay_on();
} else if (open && millis()-timestamp > OPEN_DELAY) {
open=false;
timestamp = millis();
set_relay_off();
}
}
The only reason you might want to use timer would be to save battery by keeping the AVR in sleep mode as much as possible. Then you'd set the timer to the biggest possible value before putting it to sleep, making it wake up the AVR with an interrupt every few seconds or so, so then you run the loop() once in CLOSE state going back to sleep — there you don't need to write an ISR, the main loop() is enough, or keeping it up for the full two minutes in OPEN state.
There's good documentation on timers you might want to read (beware the headaches, though):
http://maxembedded.com/2011/06/introduction-to-avr-timers/
Here's how to put the arduino to sleep for long delays:
http://www.bot-thoughts.com/2013/11/avr-watchdog-as-sleep-delay.html
HTH
I've been doing a little thermometer project to learn Arduino and there is an annoying thing that I have no idea how to resolve.
I have two push buttons to set Min and Max temperature and when I push the buttons it's supposed to set the Min and Max temperature on display.
The problem is that sometimes (50% of times) when I push the buttons during the reading of the temperature sensor, the buttons don't work. I press it but the Min/Max temperature are not set because Arduino is stuck in reading the temperature sensor.
Is there any trick to solve this kind of problem? If I had a keyboard for typing some number for example I imagine I would have the same problem and It's not "user-friendly".
Here is an example of part of the code I'm using:
#include <OneWire.h>
#include <DallasTemperature.h>
#include <LiquidCrystal.h>
//variables declaration...
void setup() {
sensors.begin();
sensors.getAddress(sensor1, 0);
pinMode(buzzer, OUTPUT);
pinMode(btBuzzer, INPUT);
pinMode(btMin, INPUT);
pinMode(btMax, INPUT);
}
void loop() {
readButtons();
playBuzzer();
readTemperature();
printDisplay();
delay(150);
}
void readButtons(){
if(digitalRead(btBuzzer)){
buzzerOn = !buzzerOn;
}
if(digitalRead(btMin)){
if(tempMin == 69)
tempMin = 59;
else
tempMin++;
}
if(digitalRead(btMax)){
if(tempMax == 75)
tempMax = 63;
else
tempMax++;
}
}
void readTemperature(){
sensors.requestTemperatures();
temperature = sensors.getTempC(sensor1);
}
//lots of other methods
As others have pointed out here, the button press may not happen at the same time as you query the pin with digitalRead(btBuzzer). This type of problem is what so called "interrupts" were invented for, which allow you to respond to events that may occur while you are not monitoring the pin of interest.
For example, the Arduino UNO R3 allow for interrupts on pin 2 and 3. You should look up the reference for attachInterrupt(). The processor will execute a callback function in the event (the "interrupt") that you register for (e.g. the voltage on pin 2 changing from low to high). This means that you will no longer have to call a readButtons() function from your main loop.
Some of the best ways to learn coding exist in how to answer this question.
What I'd like to suggest doing is to try timing your code. Remember that loop() is creating a repeating structure. So we can say things like how long does the computer take to run each loop. When we have an interrupt like a button press how does that effect the iteration through the loop and is it conditional about how to rest the processor (the delay).
The delay is required so as to not do what's called "spin" the processor (have the processor as quickly as it can do a lot of work to accomplish absolutely nothing). However, notice how the code doesn't account for work done changing how long we delay?
Now let's imagine the processor actually can go through that loop more than one time very quickly. Remember delay of only 150 milliseconds isn't a lot of time. So maybe one button press will be enough to set tempMin from 59 to 69 in rapid succession and loop several times over rather than just increasing one number at a time.
What you have here is a chance to learn debugging. First trick is to determine is the loop running too fast or too slow; are you getting desired functionality or not and finally if you can reask the question after you know if it's happening too fast or slow.
For now, I'd recommend taking a look at global variables and finite state machines (i.e. if you're in a state of button press, don't accept any further button presses until you're done with your state and only transition in known ways).
In my project, I have three buttons where each triggers a function.
This function have to do two things, one action when the button is pressed (actually working), but I want to add a second functionality, in which if the button is pressed for more then 3 seconds, it do something, like calling a function.
So far, i'm initializing the interruption:
attachInterrupt(0, footOne, Falling);
and the function is:
void footOne(){
static unsigned long last_interrupt_time = 0;
unsigned long interrupt_time = millis();
// Debounce
if (interrupt_time - last_interrupt_time > 200){
//Do things
if(debug==1){Serial.println("Button 1 pressed!");}
}
last_interrupt_time = interrupt_time;
}
Now I want to know how I can change the function to add the possibility if the button is pressed for longer then 3 seconds...
Remembering that this function is called from the interrupts.
Thank you!
With the way you have your program structured right now, you would need an external RTC to carry out this task. Once you initiate an interrupt, the internal clock on the arduino is compromised and therefore cannot be used reliably until leaving the interrupt. Is your implementation so time sensitive that an interrupt is required? Because if it isn't, polling the state of the button and then comparing the time elapsed would be a pretty easy implementation. If you want to stick with interrupts however, I'd take a look at volatile variables as a way to talk between your main loop and your interrupt functions.
Im using C language for a PIC18F to produce tones such that each of them plays at certain time-interval. I used PWM to produce a tone. But I don't know how to create the intervals. Here is my attempt.
#pragma code //
void main (void)
{
int i=0;
// set internal oscillator to 1MHz
//OSCCON = 0b10110110; // IRCFx = 101
//OSCTUNEbits.PLLEN = 0; //PLL disabled
TRISDbits.TRISD7 = 0;
T2CON = 0b00000101; //timer2 on
PR2 = 240;
CCPR1L = 0x78;
CCP1CON= 0b01001100;
LATDbits.LATD7=0;
Delay1KTCYx(1000);
while(1);
}
When I'm doing embedded programming, I find it extremely useful to add comments explaining exactly what I'm intending when I'm set configuration registers. That way I don't have to go back to the data sheets to figure out what 0x01001010 does when I'm trying to grok the code the next time I have to change it. (Just be sure to keep the comments in sync with the changes).
From what I can decode, it looks like you've got the PWM registers set up, but no way to change the frequency at your desired intervals. There are a few ways to do it, here are 2 ideas:
You could read a timer on startup, add the desired interval to get a target time, and poll the timer in the while loop. When the timer hits the target, set a new PWM duty cycle, and add the next interval to your target time. This will work fine, until you need to start doing other things in the background loop.
You could set timer0's count to 0xFFFF-interval, and set it to interrupt on rollover. In the ISR, set the new PWM duty cycle, and reset timer0 count to the next interval.
One common way of controlling timing in embedded processes looks like this:
int flag=0;
void main()
{
setup_interrupt(); //schedule interrupt for desired time.
while (1)
{
if (flag)
{
update_something();
flag = 0;
}
}
Where does flag get set? In the interrupt handler:
void InterruptHandler()
{
flag = 1;
acknowledge_interupt_reg = 0;
}
You've got all the pieces in your example, you just need to put them together in the right places. In your case, update_something() would update the PWM. The logic would look like: "If it's on, turn it off; else turn it on. Update the tone (duty cycle) if desired"
There should be no need for additional delays or pauses in the main while loop. The goal is that it just runs over and over again, waiting for something to do. If the program needs to do something else at a different rate, you can add another flag, which is triggered completely independently, and the timing of the two tasks won't interfere with each other.
EDIT:
I'm now confused about what you are trying to accomplish. Do you want a series of pulses of the same tone (on-off-on-off)? Or do you want a series of different notes without pauses (do-re-me-fa-...)? I had been assuming the latter, but now I'm not sure.
After seeing your updated code, I'm not sure exactly how your system is configured, so I'm just going to ask some questions I hope are helpful.
Is the PWM part working? Do you get the initial tone? I'm assuming yes.
Does your hardware have some sort of clock pulse hooked up to the RA4/T0CKI pin? If not, you need T0 to be clock mode, not counter mode.
Is the interrupt being called? You are setting INT0IE, which enables the external interrupt, not the timer interrupt
What interval do you want between tone updates? Right now, you are getting 0xFFFF / (clock_freq/8) You need to set the TMR0H/L registers if you want something different.
What's on LATD7? and why are you clearing it? Are you saying it enables PWM output?
Why the call to Delay()? The timer itself should be providing the needed delay. There seems to be a disconnect about how to do timing. I'll expand my other answer
Where are you trying to change the PWM frequency? Don't you need to write to PR2? You will need to give it a different value for every different tone.
"Halting build on first failure as requested."
This just says you have some syntax error, without showing us the error report, we can't really help.
In Windows you can use the Beep function in kernel32:
[DllImport("kernel32.dll")]
private static extern bool Beep(int frequency, int duration);