For a project I want to time how long a function takes. For this, I was thinking of using TimerA TA0 and a capture. However, after looking through the documentation, I was wondering if it is possible to capture the timer using an internal "message". In the datasheet (http://www.ti.com/lit/ds/symlink/msp430fr6989.pdf page 87, table at the bottom of the page) it is not really clear to me how to do this. It states the Port pins which can be used, but I am (obviously) not interested in that.
I was thus thinking if I was able to write to the TAxIV regitser, to just set the interrupt flag myself, but I'm absolutely not sure if it would work (I don't really think so, but I don't know why), I could use that to capture the timer.
I also already looked at the example code, but there they use ACLK to as an input signal. So that is not of much use either.
With kind regards and thanks in advance
As shown in the Timer_A block diagram (figure 25-1) in the User's Guide, the capture signal must come from one of the four capture inputs.
The last two inputs are always connected to GND and VCC, so you can trigger the capture manually by switching between these two inputs (see section 25.2.4.1.1).
The answer is (all thanks go to CL. ,see above, who gave the answer):
for initialisations:
TA0CCTL1 = CM_3 | CCIS_1 | SCS | CAP; // could put in interrupt here
TA0CTL = TASSEL__SMCLK | MC__CONTINUOUS; // setting the timer up with the SMCLK
and for usage, meaning capturing the timer:
TA0CCTL1 ^= CCIS0 // TA0CCR1 = TA0R, toggling the CCIS0 bit to switch between Vcc and GND
and then just reading the capture register out.
This answer is here to make it easier to read, for the full answer see my conversation with CL. above, whom gave me the answer.
Related
I'm struggeling on setting up a STM32-F429ZI MCU (Nucleo 144 board) to generate following PWM pattern:
First channel with a variable frequency and 50% duty cycle - at least I've got this working -
Second channel giving a pulse with each 20th pulse of channel 1.
This is not primary a coding problem but a understanding problem of timer settings i guess (working with STM32CubeIDE). I would bet there is real simple solution...
I Think there is no way to do this with only 1 timer?
I'm pleased for any suggestion...
I already tried with TIM2 as clock source for TIM3 and 4 but couldn't manage to make them synchonize.
For better illustration of what I want to do:
I't not sure, if it could be done with two timer synchronization (the pitfall is variable frequency of the first timer). But you can use single timer+DMA to rewrite configuration of the second channel:
Create in-memory array of 20 values, where one value enables the second channel and other 19 disables it
Setup DMA to trigger on the timer update and to move data from the array to CCMRx (or CCRx) register. Of cource, DMA should be in circular mode
In my software I need to detect when an operator toggles one of two miniature toggle electric switches:
and which one.
I want to do this with as little external hardware as possible.
I was thinking that maybe I could use a USB to serial cable?
Looking at the WaitCommEvent documentation I notice that I can listen to for instance:
EV_CTS: The CTS (clear-to-send) signal changed state.
EV_DSR: The DSR
(data-set-ready) signal changed state.
Looking at the DB-9 pins:
It seems that I could connect a voltage source trough the toggle 1 to pin 8 (CTS) and to ground?
Likewise it seems that I could connect a voltage source trough the toggle 2 to pin 6 (DSR) and to ground?
Will this work? Is there a better way to do this only using a USB to serial cable?
For the sake of sparing you the work of reposting to the electronics exchange:
According to this document, setting CTS on means a voltage of at least +3V on the CTS line, relative to GND. Similarly, setting CTS off means a voltage of at least -3V on the CTS line, relative to GND. So you'd need two voltage sources, one for >+3V (GND to Serial GND) and one isolated one for <-3V (Plus to Serial GND).
DSR functions similarly, according to the document.
Also, your switch looks like an SPST. You'd need at least an SPDT for this if you want to avoid using resistors.
I have a timer set up in the cube to make a PWM... Just setting ARR and CCR to different values.
I'm using the callback functions for both events that HAL set up for me, I think one is for the CCR compare event and the other is for the ARR compare event.
Anyway, in both of those I'm toggling a GPIO port like this:
GPIOC->ODR = foo;
Anyway, I want to sample the values of 3 ADC1 channels during the high pulse, but I'm not sure how to do that accurately. I'm using DMA in circular mode with the ADC1 right now.
I don't want to sample immediately after setting the pins, because there's propagation delay, noise, etc.
So, I want to:
Set the pins, wait a very short and constant amount of time, sample all the channels and then do some math on the results.
This is for a Bldc motor controller, by the way... Im trying to sample the BEMF on the positive side of the PWM drive signal, and I'm driving it at 18khz, 5% duty cycle, so my pulse lasts for 2.7us.
I'm not sure how to handle or debug this because it's so timing related and I need the motor to deliver the signal that I'm using... If the motor isn't spinning, then there's no feedback signal to work on. It sure seems like I'm trying to do too much in the timer ISRs, though.
Sorry I can't post any code right now... Im at the grocery store, but I'll put some up when I get back.
I am trying to implement PWM LED dimming in 6 stages, where each stage in more bright, based on clicking button, which increments external pin, which serves the value to timer.
I am facing a problem, that sometimes, value variable is too large than it should be and skips some levels of brightness. For example, value increments: 1,2,3, then jumps to 6,7, etc.
Can anybody pinpoint where is the mistake I am making.
Here is the code:
//EDIT: code removed, because it is a school assignment
This looks like contact bouncing. When input is processed by the CPU, a simple way to solve it is to disable input for a certain duration after an event is detected. Since you directly control timer input from a button, you may not have much control. However, I would experiment with the ETF field of the SMCR register (which in your case is likely set by the sClockSourceConfig.ClockFilter field) and the clock divisor CKD of the CR1 register (which seems like htim2.Init.ClockDivision in your code) (sorry, I am not familiar with STM libraries).
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);