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[Reply #60 on:]

Hi!
I read trough this thread and find it very very helpful!
At the moment i am trying to measure times between signal-flanks. Therefore i need to stop the time between two (external)interrupts. I'd like to do this with a timer - but don't need the timer interrupt.
As far as i can see the actual time is hold in the TC_CV register. How do i get this value?
I saw you make a lot of use of functions like pmc_set_write_protect and others. Where do you get the documentation of these functions from? And why do you know they even exist?
Thanks a lot!

[Reply #61 on:]

Here is a link to the new library version: https://github.com/SomeRandomGuy/DueTimer

Could someone offer some more explanation on this library I am trying to get my head around it.
I would like to set up a 500Khz clock output to a ATA6870. Is this possible using this library?
Does setting up these timers on certain pins have any affects on other parts of the system like the SPI Bus as I am using this to communicate with the ATA6870 which will use a SCK of half the CLK input I provide as recommended in the ATA6870 datasheet?

[Reply #62 on:]

I am new to ARM processor and I am struggling making the timer work as well. The content in this post have been very helpful. But I have a very very dumb question.

Where did you guys find the reference manual for those functions used in these code?  Like(NVIC_EnableIRQ,  TC_Configure, TC_SetRA, etc). From the files in IDE it seems to be a library from Atmel. I probably used wrong keyword; I tried to search those on google for hours and got nothing.     

[Reply #63 on:]

I used:
1. ATMEL data sheet: http://www.atmel.com/Images/doc11057.pdf
2. API ref:  http://asf.atmel.com/docs/latest/api.html
3. the code (in the arduino dist)

You have to do some homework as none of the above is a tutorial.   Most of the functions/defines were not obvious until I read the code.   Had to do the same thing for the DAC interface (e.g., to enable flexible & word mode updates).

Best,
Bruce

[Reply #64 on:]

This may be off topic, but is it possible to modify the library to be able to measure pulse duration on a pin using the timer interrupts?

Many thanks for your time in advance

Kind regards Rob

[Reply #65 on:]

I used:
1. ATMEL data sheet: http://www.atmel.com/Images/doc11057.pdf
2. API ref:  http://asf.atmel.com/docs/latest/api.html
3. the code (in the arduino dist)

You have to do some homework as none of the above is a tutorial.   Most of the functions/defines were not obvious until I read the code.   Had to do the same thing for the DAC interface (e.g., to enable flexible & word mode updates).

Best,
Bruce

Thank you very much for your reply,  that is the sort of stuff I want.

I have one more question though. I cannot find some functions, for instance  "TC_Configure()" in this API. I choose Timer Counter as catalog and SAM3X as devices.  There is a function called "void    tc_init (Tc *p_tc, uint32_t ul_channel, uint32_t ul_mode)" with same signature but the name is different and it cannot be compiled.   Can you please tell me where do I find the information for those functions that compile-able by the arduino compiler?

[Reply #66 on:]

I found the source for TC_Configure() in the arduino dist (.../hardware/arduino/sam/system/libsam/{include/tc.h,source/tc.c}).   

In this case, it appears that the ATMEL documentation and the code in the arduino dist do not match.   The documentation for tc_init() appears to match the source code for TC_Configure (caveat: I just took a quick look, but it appears to be essentially the same function).   My guess is that they renamed the function at some point, and that the docs and code diverged.

The source for TC_Configure is pretty clear if you also look at the SAM3X data sheet for the behavior of the TC registers.

Best,
Bruce
 

[Reply #67 on:]

Thank you very much!  Seems like I have a lot of homework to do.

Best,
Tian

[Reply #68 on:]

Guys!

Your solution is awesome and now I can use pin 13 and pin 2 to make two different LEDs blink independently with different frequencies.
But what if I use the "Serial monitor" to manipulate the frequency?

For example, I know that in the following code if I change

  uint32_t rc = VARIANT_MCK/1300/frequency;

to

  uint32_t rc = VARIANT_MCK/128/frequency; 


it flashes slower....

but I want to make a serial loop in a way that it asks the user to change this number by putting a new number and read to serial monitor.

The problem is that I cannot put serial monitor in
Void Timer section!

Any solution that can help me please?

Thanks!

[Reply #69 on:]

Hi!
As i like libraries, i have done one to the Arduino DUE.

You can check it out here: https://github.com/ivanseidel/DueTimer

All 6 timers are fully implemented, and ready to play with...

Thanks for the tips on the topic! I will put your names there

[Reply #70 on:]

ivanseidel,

nice library!

Why don't you add also TC2 to the set of TImers? this will makes available other 3 timers.

[Reply #71 on:]

Good idea... will do it now =]

[Reply #72 on:]

Done! 

[Reply #73 on:]

Can anyone kindly let me know how I can have an exact frequency of 1HZ or period of 1sec out of the following code please?

I have changed the TC_RC to
 REG_TC0_RC0 =.25*0x5f5e100;

But I am not sure if this is 1sec or not?

Thanks all.








volatile boolean l;

void TC0_Handler()
{
    long dummy=REG_TC0_SR0; // vital - reading this clears some flag
                            // otherwise you get infinite interrupts
    l= !l;
}

void setup(){
  pinMode(13,OUTPUT);
  pinMode(2,OUTPUT);    // port B pin 25 
  analogWrite(2,255);   // sets up some other registers I haven't worked out yet
  REG_PIOB_PDR = 1<<25; // disable PIO, enable peripheral
  REG_PIOB_ABSR= 1<<25; // select peripheral B
  //REG_TC0_WPMR=0x54494D00; // enable write to registers
  REG_TC0_CMR0=0b00000000000010011100010000000000; // set channel mode register (see datasheet)
  REG_TC0_RC0 =.25*0x5f5e100; // counter period      ----  POW (base, exponent)     .5 ==> almost 1sec   10^8 = 0x5F5E100
  //REG_TC0_RA0=30000000;  // PWM value
  REG_TC0_CCR0=0b101;    // start counter
  REG_TC0_IER0=0b00010000; // enable interrupt on counter=rc
  REG_TC0_IDR0=0b11101111; // disable other interrupts

  NVIC_EnableIRQ(TC0_IRQn); // enable TC0 interrupts

}

void loop(){
      digitalWrite(13,l);
}

[Reply #74 on:]

Thanks to "stimmer" I got the right frequency of 1HZ or Period of 1sec, luckily. My next step is to use the
"Serial Monitor" to change the frequency.

When I use the following approach. And put something in the command line it starts to blink but it is not the exact frequency.
Afterwards, when I put another amount in the command line, the frequency does not change.

What do you suggest to read from the Serial monitor to change the frequency?

Thank you.

Code:

volatile boolean l;


void TC0_Handler()
{
    long dummy=REG_TC0_SR0; // vital - reading this clears some flag
                            // otherwise you get infinite interrupts
    l= !l;
}

void setup(){
  Serial.begin(9600);
  pinMode(13,OUTPUT);
  pinMode(2,OUTPUT);    // port B pin 25 
  analogWrite(2,255);   // sets up some other registers I haven't worked out yet
  REG_PIOB_PDR = 1<<25; // disable PIO, enable peripheral
  REG_PIOB_ABSR= 1<<25; // select peripheral B
  REG_TC0_CMR0=0b00000000000010011100010000000000; // set channel mode register (see datasheet)
  REG_TC0_CCR0=0b101;    // start counter
  REG_TC0_IER0=0b00010000; // enable interrupt on counter=rc
  REG_TC0_IDR0=0b11101111; // disable other interrupts

  NVIC_EnableIRQ(TC0_IRQn); // enable TC0 interrupts

}


void loop(){
   
       digitalWrite(13,l);

          if (Serial.available() > 0) {

int x = Serial.read();

REG_TC0_RC0 = x*pow(10,6);  // counter period      ----  POW (base, exponent)     .5 ==> almost 1sec   10^8 = 0x5F5E100   

}
       
       
}