#include "mbed.h"
InterruptIn button(p5);
DigitalOut led(LED1);
DigitalOut flash(LED4);
void flip() {
led = !led;
}
int main() {
button.rise(&flip); // attach the address of the flip function to the rising edgewhile(1) { // wait around, interrupts will interrupt this!
flash = !flash;
wait(0.25);
}
}
The pin input will be logic '0' for any voltage on the pin below 0.8v, and '1' for any voltage above 2.0v. By default, the InterruptIn is setup with an internal pull-down resistor.
No blocking code in ISR
In ISR you should avoid any call to wait, infinitive while loop, or blocking calls in general.
No printf, malloc, or new in ISR
In ISR you should avoid any call to bulky library functions. In particular, certain library functions (like printf, malloc and new) are non re-entrant and their behaviour could be corrupted when called from an ISR.
I have two InterruptIn pins and two different functions when pins are asserted. I noticed that only 1 ISR is executed. Other is not even once executed!!!! Can anyone help me on this????
Nitin
I have two InterruptIn pins and two different functions when pins are asserted. I noticed that only 1 ISR is executed. Other is not even once executed!!!! Can anyone help me on this????
Nitin
Hi Igor,
I am not using p19,p20. I am trying to interface OV7670 camera. Initialization is done by atmega32. TRIG pin is toggled once to indicate atmega32 to start initialization. After initialization, Atmega32 sets ECHO pin in order to acknowledge the initialization request. After initialization, I am supposed to get 16-bit data from cam. Cam's data lines are 8-bit. So, 16-bit is got when PCLK(CAM) pin toggles twice. There is also a VSYNC pin to indicate the start of frame. So I have 2 ISR as there are 2 InterruptIn pin. Following is the code, Only ISR vsync() gets executed. ISR pclk() is not executed even once. When i comment out ISR vsync(), ISR pclk() gets executed upon interrupt request!!!! And one more problem is that when I try reading the 8-bit data lines in BusIn mode, I get proper data (ISR vsync() commented). But in PortIn mode I get garbage data. Please help me....
#include "mbed.h"
#include "pcf8833.h" //Nokia 6100 LCD header
/*
Camera data pins Mbed pins
D0 p26
D1 p25
D2 p24
D3 p23
D4 p22
D5 p21
D6 p19
D7 p20
*/
PortIn PORT1(Port1,0xC0000000); //Camera output data D7,D6
PortIn PORT2(Port2,0x3F); //Camera output data D5-D0
DigitalOut myled(LED1);
DigitalOut OSC_E(p7); //Camera oscillation Enable pin
DigitalOut TRIG(p8); //Trigger pin used to request camera initialization(initialization will be done by atmega32)
DigitalIn ECHO(p9); //Echo pin is set by atmega32 in order to indicate that its has completed initializing the camera
InterruptIn VSYNC(p5); //Camera VSYNC
InterruptIn PCLK(p14); //Camera pixel clk
unsigned int count,count1;
void pclk(void)
{
OSC_E=0; //stop camera oscillation
WriteSpiData(((PORT1.read()>>24)&0xC0)|(PORT2.read()&0x3F)); //read 8-bit data on display on Nokia LCD
OSC_E=1; //start camera oscillation
}
void vsync(void)
{
OSC_E=0;
WriteSpiCommand(PASET); //To set LCD cursor position at 0,0
WriteSpiData(0);
WriteSpiData(131);
WriteSpiCommand(CASET);
WriteSpiData(0);
WriteSpiData(131);
WriteSpiCommand(RAMWR);
OSC_E=1;
}
int main() {
wait(1);
InitLcd();
LCDClearScreen(Red);
LCDClearScreen(Green);
OSC_E=1;
TRIG=1;
TRIG=0;
while(!ECHO);
PCLK.rise(&pclk);
VSYNC.fall(&vsync);
while(1) {
}
}
Thanks
Nitin
Hi Igor,
I am not using p19,p20. I am trying to interface OV7670 camera. Initialization is done by atmega32. TRIG pin is toggled once to indicate atmega32 to start initialization. After initialization, Atmega32 sets ECHO pin in order to acknowledge the initialization request. After initialization, I am supposed to get 16-bit data from cam. Cam's data lines are 8-bit. So, 16-bit is got when PCLK(CAM) pin toggles twice. There is also a VSYNC pin to indicate the start of frame. So I have 2 ISR as there are 2 InterruptIn pin. Following is the code, Only ISR vsync() gets executed. ISR pclk() is not executed even once. When i comment out ISR vsync(), ISR pclk() gets executed upon interrupt request!!!! And one more problem is that when I try reading the 8-bit data lines in BusIn mode, I get proper data (ISR vsync() commented). But in PortIn mode I get garbage data. Please help me....
<<code>>
#include "mbed.h"
#include "pcf8833.h" //Nokia 6100 LCD header
/*
Camera data pins Mbed pins
D0 p26
D1 p25
D2 p24
D3 p23
D4 p22
D5 p21
D6 p19
D7 p20
*/
PortIn PORT1(Port1,0xC0000000); //Camera output data D7,D6
PortIn PORT2(Port2,0x3F); //Camera output data D5-D0
DigitalOut myled(LED1);
DigitalOut OSC_E(p7); //Camera oscillation Enable pin
DigitalOut TRIG(p8); //Trigger pin used to request camera initialization(initialization will be done by atmega32)
DigitalIn ECHO(p9); //Echo pin is set by atmega32 in order to indicate that its has completed initializing the camera
InterruptIn VSYNC(p5); //Camera VSYNC
InterruptIn PCLK(p14); //Camera pixel clk
unsigned int count,count1;
void pclk(void)
{
OSC_E=0; //stop camera oscillation
WriteSpiData(((PORT1.read()>>24)&0xC0)|(PORT2.read()&0x3F)); //read 8-bit data on display on Nokia LCD
OSC_E=1; //start camera oscillation
}
void vsync(void)
{
OSC_E=0;
WriteSpiCommand(PASET); //To set LCD cursor position at 0,0
WriteSpiData(0);
WriteSpiData(131);
WriteSpiCommand(CASET);
WriteSpiData(0);
WriteSpiData(131);
WriteSpiCommand(RAMWR);
OSC_E=1;
}
int main() {
wait(1);
InitLcd();
LCDClearScreen(Red);
LCDClearScreen(Green);
OSC_E=1;
TRIG=1;
TRIG=0;
while(!ECHO);
PCLK.rise(&pclk);
VSYNC.fall(&vsync);
while(1) {
}
}
<</code>>
Thanks
Nitin
Does InterruptIn have priority over rest of the code? What i am trying to do is to increase the value of a variable even when the code is stuck with an other line of the code. (Writing in a file in my case)
thanks
Levi
Hello,
Does InterruptIn have priority over rest of the code? What i am trying to do is to increase the value of a variable even when the code is stuck with an other line of the code. (Writing in a file in my case)
thanks
Levi
I'm about to use multiple interrupts too so I've made some tests. It turn out that when I wired two pins, with different ISRs, to the same interrupt source, sometimes (!) only one routine get to execute. Triggered separately they both work as expected. To be fair it's a breadboard test with some dirty wiring and no debouncing that may cause loss of a flank to one of the interrupts. A quick (i.e not very computed) lowpass filter does not eliminate the problem but makes it occur less frequent.
My vote is on the electrical.
/Per
@Nitin
I'm about to use multiple interrupts too so I've made some tests. It turn out that when I wired two pins, with different ISRs, to the same interrupt source, sometimes (!) only one routine get to execute. Triggered separately they both work as expected. To be fair it's a breadboard test with some dirty wiring and no debouncing that may cause loss of a flank to one of the interrupts. A quick (i.e not very computed) lowpass filter does not eliminate the problem but makes it occur less frequent.
My vote is on the electrical.
/Per
once created an InterruptIn and .rise attached to it, how to stop them?
I use p17, p18.
I tried to delete the entire InterruptIn object, but they still keep responding.
Bug or feature?
Or did I understand something wrong regarding deleting objects.
Thanks Ju
Hello,
once created an InterruptIn and .rise attached to it, how to stop them?
I use p17, p18.
I tried to delete the entire InterruptIn object, but they still keep responding.
Bug or feature?
Or did I understand something wrong regarding deleting objects.
Thanks Ju
This function is working fine for me with one exception.
How can I initialize the state? Depending on when I boot up my sensor is either HIGH or LOW and I need to display that on my screen. Any ideas how to read the state of the pin and then 'force' the appropriate interrupt so I have the correct startup state displayed?
Since this is an interrupt function, there is no way to read the initial value.
Hi there.
This function is working fine for me with one exception.
How can I initialize the state? Depending on when I boot up my sensor is either HIGH or LOW and I need to display that on my screen. Any ideas how to read the state of the pin and then 'force' the appropriate interrupt so I have the correct startup state displayed?
Since this is an interrupt function, there is no way to read the initial value.
I have a question about the digital inputs on the mbed. I read the tutorial
posted on the mbed website that gives some basic programming guides and
examples.
What I'm interested in is looking at one of the digital inputs for a certain
period of time. For example, if the input is high for 5
seconds continuously without fluctuations, then and only then send the
desired output.
I know that I can implement this using some conditional programming and IF
conditions, but I don't know how to tell the mbed to look at the input for a
specific amount of time.
Can anyone please help me with this?
I have a question about the digital inputs on the mbed. I read the tutorial
posted on the mbed website that gives some basic programming guides and
examples.
What I'm interested in is looking at one of the digital inputs for a certain
period of time. For example, if the input is high for 5
seconds continuously without fluctuations, then and only then send the
desired output.
I know that I can implement this using some conditional programming and IF
conditions, but I don't know how to tell the mbed to look at the input for a
specific amount of time.
Can anyone please help me with this?
There are a few ways depending on your system and how fast this input may change.
1) Stay in a loop for 5 seconds and continually poll the input. Exit on a timer or a change in pin level.
2) Set up a timer interrupt. (Ticker) and have an interrupt occur every 100ms. Check the state of the pin every 100ms (on the Ticker interrupt) and count up to 5 seconds. When the 5 seconds is up, disable the timer.
3) Start a timer and check that timer when an interrupt on that pin finally occurs. If it is past the 5 seconds, then the data is valid, if it is before the 5 seconds, then the ISR simply ignores the data.
There are a few more but this will at least get you started.
Eric:
There are a few ways depending on your system and how fast this input may change.
1) Stay in a loop for 5 seconds and continually poll the input. Exit on a timer or a change in pin level.
2) Set up a timer interrupt. (Ticker) and have an interrupt occur every 100ms. Check the state of the pin every 100ms (on the Ticker interrupt) and count up to 5 seconds. When the 5 seconds is up, disable the timer.
3) Start a timer and check that timer when an interrupt on that pin finally occurs. If it is past the 5 seconds, then the data is valid, if it is before the 5 seconds, then the ISR simply ignores the data.
There are a few more but this will at least get you started.
I just made a measuremement using mbed2368 in an oscilloscope to see how fast my InterruptIn responds?
I found it is 10uS. Do you people think my measurement is correct, if yes Is there any way
the 10uS latency can be reduced say towards 1uS?
code I tested: with osciloscope channel1 connected to clk (square pulse generated in main p21) and second channel of CRO one to output(p22).
and saw the delay between the rising edges to be 10uS.
int main() {
button.rise(&flip); attach the address of the flip function to the rising edge
while(1) { wait around, interrupts will interrupt this!
flash = !flash;
clk = !clk;
wait(0.25);
}
}
pl. comment.
I just made a measuremement using mbed2368 in an oscilloscope to see how fast my InterruptIn responds?
I found it is 10uS. Do you people think my measurement is correct, if yes Is there any way
the 10uS latency can be reduced say towards 1uS?
code I tested: with osciloscope channel1 connected to clk (square pulse generated in main p21) and second channel of CRO one to output(p22).
and saw the delay between the rising edges to be 10uS.
#include "mbed.h"
DigitalOut clk(p21);
InterruptIn button(p26);
DigitalOut output(p22);
DigitalOut flash(LED1);
void flip() {
output = !output;
}
int main() {
button.rise(&flip); // attach the address of the flip function to the rising edge
while(1) { // wait around, interrupts will interrupt this!
flash = !flash;
clk = !clk;
wait(0.25);
}
}
pl. comment.
Hi:
In the InterruptIn example above, if the interrupt pin is set to p20 for mbed LPC1768, it will not work.
<<code>>
#include "mbed.h"
InterruptIn button(p20);
DigitalOut led(LED1);
DigitalOut flash(LED4);
void flip() {
led = !led;
}
int main() {
button.rise(&flip); // attach the address of the flip function to the rising edge
while(1) { // wait around, interrupts will interrupt this!
flash = !flash;
wait(0.25);
}
}
<</code>>
From [[http://mbed.org/projects/libraries/svn/mbed/trunk/PinNames.h?rev=31|PinName.h]], for LPC1768
##p20 = P0_22##
##LED1 = P1_8##
##LED2 = P1_9##
##LED3 = P1_10##
##LED4 = P1_11##
Any clue?
p19 and p20 are on port1
http://mbed.org/users/Lerche/notebook/lpc1768-pin-functions/
In pinname.h it says (following your link):
<<quote>>
57 , p19 = P1_30
58 , p20 = P1_31
<</quote>>
1. If I directly call button_ISR from Main, I get the expected printout.
2. My problem is with getting the interrupt to occur. I have a wire with one end connected to p21 (VOUT). I momentarily insert the other end into p5 on a breadboard or directly touch p5 and expect the interrupt to occur. Is this not right? Should I do something else?
Thanks.
I am having problems with the following code.
Main.cpp
<<code>>
#include "mbed.h"
#include "rtos.h"
#include "os_tasks.h"
#include "isr.h"
DigitalOut led1(LED1);
DigitalOut led2(LED2);
DigitalOut led3(LED3);
Serial pc(USBTX, USBRX); // tx, rx
InterruptIn button(p5);
int main(void) {
button.rise(&button_ISR);
RtosTimer os_5ms_timer(os_5ms_task, osTimerPeriodic, (void *)0);
os_5ms_timer.start(5);
Thread::wait(osWaitForever);
}
<</code>>
isr.cpp
<<code>>
#include "mbed.h"
#include "os_tasks.h"
#include "objects.h"
void button_ISR() {
pc.printf("In button_ISR \n\r");
}
<</code>>
1. If I directly call button_ISR from Main, I get the expected printout.
2. My problem is with getting the interrupt to occur. I have a wire with one end connected to p21 (VOUT). I momentarily insert the other end into p5 on a breadboard or directly touch p5 and expect the interrupt to occur. Is this not right? Should I do something else?
Thanks.
Never used RTOS, so dunno if that code is all correct. However by default pull-ups are enabled on all pins, so they are high state, you dont change that, and you connect an interrupt on rising edge of the pin. However since the pin will always be high the interrupt never happens.
Quick way to check it would be to connect p5 to GND, and then remove that connection. Pull up should then give you a rising edge that it should trigger on. (Btw p21 is a GPIO pin, I think you mean p40, numbering on right side is inverted compared to left side).
Never used RTOS, so dunno if that code is all correct. However by default pull-ups are enabled on all pins, so they are high state, you dont change that, and you connect an interrupt on rising edge of the pin. However since the pin will always be high the interrupt never happens.
Quick way to check it would be to connect p5 to GND, and then remove that connection. Pull up should then give you a rising edge that it should trigger on. (Btw p21 is a GPIO pin, I think you mean p40, numbering on right side is inverted compared to left side).
Vout is p40, not p21.
You probably need a puldown resistor on the inputpin to make sure it is at low-level during idle state and detects a rising edge when you momentarily connect the wire.
It is likely that you get multiple interrupts when you touch the pin with a wire.
Vout is p40, not p21.
You probably need a puldown resistor on the inputpin to make sure it is at low-level during idle state and detects a rising edge when you momentarily connect the wire.
It is likely that you get multiple interrupts when you touch the pin with a wire.
Indeed Vout is p40, not p21. I had the right pin but was counting it wrong from top to bottom on the right side also.
I still can't get interrupt to work. I wonder whether I am getting multiple interrupts I don't quite believe this either.
I can read p5 as digitalin. As is, it comes up low. When I short it to vout, it comes up high. This is different from what you guys are saying above but agrees with the http://www.amazon.com/Fast-Effective-Embedded-Systems-Design/dp/0080977685. I can post the page number later if someone wishes.
Can someone else try the interruptin? Thanks.
Indeed Vout is p40, not p21. I had the right pin but was counting it wrong -- from top to bottom on the right side also.
I still can't get interrupt to work. I wonder whether I am getting multiple interrupts -- I don't quite believe this either.
I can read p5 as digitalin. As is, it comes up low. When I short it to vout, it comes up high. This is different from what you guys are saying above but agrees with the http://www.amazon.com/Fast-Effective-Embedded-Systems-Design/dp/0080977685. I can post the page number later if someone wishes.
Can someone else try the interruptin? Thanks.
You are right, by default inputs are set as pull-down (not what you would expect imo, but you are right). But undefined pins have pull up enabled (at least I can get your rising edge interrupt to happen by connecting p5 to random other pin).
Anyway found your interrupt problem, it was the little issue that I have no experience with RTOS, but I happened to read a bit about it yesterday, and the important part:
Quote:
Because of the mutexes in the ARM C standard library you can not use printf, malloc and new in ISR!
Now I still dont have a clue what a mutex is :P, but you arent allowed to use printf in an ISR, there is your problem. I checked it with toggling an LED instead of using printf, and that works fine (by connecting p5 to p40). Do take into account you will get multiple interrupts, unless you add debouncing.
You are right, by default inputs are set as pull-down (not what you would expect imo, but you are right). But undefined pins have pull up enabled (at least I can get your rising edge interrupt to happen by connecting p5 to random other pin).
Anyway found your interrupt problem, it was the little issue that I have no experience with RTOS, but I happened to read a bit about it yesterday, and the important part:
<<quote>>
Because of the mutexes in the ARM C standard library you can not use printf, malloc and new in ISR!
<</quote>>
Now I still dont have a clue what a mutex is :P, but you arent allowed to use printf in an ISR, there is your problem. I checked it with toggling an LED instead of using printf, and that works fine (by connecting p5 to p40). Do take into account you will get multiple interrupts, unless you add debouncing.
The example for InterruptIn in the book did use LED toggles. I wish that I had tried the example exactly as specified in the book :-)
Thanks a whole bunch. Have a great day.
Erik,
The example for InterruptIn in the book did use LED toggles. I wish that I had tried the example exactly as specified in the book :-)
Thanks a whole bunch. Have a great day.
I have this really silly problem with Interrupts. I connected my mBed pin p8 to a function generator and provided a square wave of 1Khz to that pin. I am not sure why the code doesn't enter into the interrupt function. I have just copied and pasted the same example code given on the top of the page.
My ultimate goal is to make a frequency counter with the mBed.
I have this really silly problem with Interrupts. I connected my mBed pin p8 to a function generator and provided a square wave of 1Khz to that pin. I am not sure why the code doesn't enter into the interrupt function. I have just copied and pasted the same example code given on the top of the page.
My ultimate goal is to make a frequency counter with the mBed.
I have this really silly problem with Interrupts. I connected my mBed pin p8 to a function generator and provided a square wave of 1Khz to that pin. I am not sure why the code doesn't enter into the interrupt function. I have just copied and pasted the same example code given on the top of the page.
My ultimate goal is to make a frequency counter with the mBed.
And you have checked that the InterruptIn is set for p8 right? :-)
And that you have GND connected to GND from the freqgen? :-)
Lerche
<<quote Neel>>
I have this really silly problem with Interrupts. I connected my mBed pin p8 to a function generator and provided a square wave of 1Khz to that pin. I am not sure why the code doesn't enter into the interrupt function. I have just copied and pasted the same example code given on the top of the page.
My ultimate goal is to make a frequency counter with the mBed.
<</quote>>
And you have checked that the InterruptIn is set for p8 right? :-)
And that you have GND connected to GND from the freqgen? :-)
Lerche
@Lerche: Yes I have checked that! and my GNDs are also connected.
Furthermore I have also got an o'scope connected to the pin just to verify that the freqgen is really generating a square wave at 1Khz. Also I have varied the frequency from 300Hz to 1Khz!
Don't exactly know whats going wrong!
@Lerche: Yes I have checked that! and my GNDs are also connected.
Furthermore I have also got an o'scope connected to the pin just to verify that the freqgen is really generating a square wave at 1Khz. Also I have varied the frequency from 300Hz to 1Khz!
Don't exactly know whats going wrong!
Is the first example correct. I can't seem to get it working. Only led4 is blinking.
Could you get it to work? The same is happening to me as well.
<<quote DimiterK>>
Is the first example correct. I can't seem to get it working. Only led4 is blinking.
<</quote>>
Could you get it to work? The same is happening to me as well.
int main() {
button.rise(&flip); attach the address of the flip function to the rising edge
while(1) { wait around, interrupts will interrupt this!
flash = !flash;
wait(0.25);
}
}
Here only led4 is toggling and not 1
@lerche:
Here you go:
#include "mbed.h"
InterruptIn button(p5);
DigitalOut led(LED1);
DigitalOut flash(LED4);
void flip() {
led = !led;
}
int main() {
button.rise(&flip); // attach the address of the flip function to the rising edge
while(1) { // wait around, interrupts will interrupt this!
flash = !flash;
wait(0.25);
}
}
Here only led4 is toggling and not 1
include "mbed.h"
InterruptIn button(p5);
DigitalOut led(LED1);
DigitalOut flash(LED4);
void flip() {
led = !led;
}
int main() {
button.rise(&flip); //attach the address of the flip function to the rising edge
while(1) {
flash = !flash;
wait(0.25); //wait around, interrupts will interrupt this!
}
}
The button referring to your freqgen right?
Have you got a scope?
Then you could check the signal on p5 on the mbed.
Lerche
Neel:
Code tags help a lot:
<<code>>
include "mbed.h"
InterruptIn button(p5);
DigitalOut led(LED1);
DigitalOut flash(LED4);
void flip() {
led = !led;
}
int main() {
button.rise(&flip); //attach the address of the flip function to the rising edge
while(1) {
flash = !flash;
wait(0.25); //wait around, interrupts will interrupt this!
}
}
<</code>>
The button referring to your freqgen right? \\
Have you got a scope? \\
Then you could check the signal on p5 on the mbed.
\\
Lerche
hi I want to design a controller to lower the speed of a motor if it exceeds a preset value. that means I have to know the know the current speed and compare with the set value. I tried to use an interruptin to count the number of pulses from a shaft encoder attached to the dc motor. but it wasn't working. can anyone help me with the cide that count the number of pulses in a second; hence determine the speed of the motor? .Thanks
hi I want to design a controller to lower the speed of a motor if it exceeds a preset value. that means I have to know the know the current speed and compare with the set value. I tried to use an interruptin to count the number of pulses from a shaft encoder attached to the dc motor. but it wasn't working. can anyone help me with the cide that count the number of pulses in a second; hence determine the speed of the motor? .Thanks
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