Comments (9)
khoih-prog
commented on June 12, 2024
Hi @wcwuttke
Thanks for your interests in the library.
- I think you have to use 16MHz clock to Timers for better accuracy
// Select USING_16MHZ == true for 16MHz to Timer TCBx => shorter timer, but better accuracy
// Select USING_8MHZ == true for 8MHz to Timer TCBx => shorter timer, but better accuracy
// Select USING_250KHZ == true for 250KHz to Timer TCBx => shorter timer, but better accuracy
// Not select for default 250KHz to Timer TCBx => longer timer, but worse accuracy
#define USING_16MHZ true
#define USING_8MHZ false
#define USING_250KHZ false
also megaAVR is a very slow MCU, doing to many things within 10ms, such as
//timer interrupt toggles pin LED_BUILTIN
digitalWrite(LED_BUILTIN, toggle1);
digitalWrite(A0, toggle1);
possibly distorts its timings.
- Try this example ISR_16_Timers_Array_Complex.
The best way to know the timings is correct is to use a counter inside the ISR, then print it out using a timing loop outside ISR, using millis().
For example, you can see the timing is very accurate here
Starting ISR_16_Timers_Array_Complex on megaAVR Nano Every
megaAVR_TimerInterrupt v1.3.0
CPU Frequency = 16 MHz
TCB Clock Frequency = 16MHz for highest accuracy
[TISR] TCB 1
[TISR] ==================
[TISR] Init, Timer = 1
[TISR] CTRLB = 0
[TISR] CCMP = 65535
[TISR] INTCTRL = 0
[TISR] CTRLA = 1
[TISR] ==================
[TISR] Frequency = 200.00 , CLK_TCB_FREQ = 16000000
[TISR] setFrequency: _CCMPValueRemaining = 80000
[TISR] ==================
[TISR] set_CCMP, Timer = 1
[TISR] CTRLB = 0
[TISR] CCMP = 65535
[TISR] INTCTRL = 1
[TISR] CTRLA = 1
Starting ITimer1 OK, millis() = 13
SimpleTimer : 2, ms : 10013, Dms : 10013
Timer : 0, programmed : 5000, actual : 5015
Timer : 1, programmed : 10000, actual : 0
Timer : 2, programmed : 15000, actual : 0
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 20072, Dms : 10059
Timer : 0, programmed : 5000, actual : 4998
Timer : 1, programmed : 10000, actual : 9995
Timer : 2, programmed : 15000, actual : 15017
Timer : 3, programmed : 20000, actual : 20015
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 30131, Dms : 10059
Timer : 0, programmed : 5000, actual : 4997
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 15000
Timer : 3, programmed : 20000, actual : 20015
Timer : 4, programmed : 25000, actual : 25020
Timer : 5, programmed : 30000, actual : 30017
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 40192, Dms : 10061
Timer : 0, programmed : 5000, actual : 5005
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 15000
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25020
Timer : 5, programmed : 30000, actual : 30017
Timer : 6, programmed : 35000, actual : 35014
Timer : 7, programmed : 40000, actual : 40019
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 50252, Dms : 10060
Timer : 0, programmed : 5000, actual : 4997
Timer : 1, programmed : 10000, actual : 9995
Timer : 2, programmed : 15000, actual : 15000
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 24994
Timer : 5, programmed : 30000, actual : 30017
Timer : 6, programmed : 35000, actual : 35014
Timer : 7, programmed : 40000, actual : 40019
Timer : 8, programmed : 45000, actual : 45017
Timer : 9, programmed : 50000, actual : 50014
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 60314, Dms : 10062
Timer : 0, programmed : 5000, actual : 4997
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 14999
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 24994
Timer : 5, programmed : 30000, actual : 29999
Timer : 6, programmed : 35000, actual : 35014
Timer : 7, programmed : 40000, actual : 40019
Timer : 8, programmed : 45000, actual : 45017
Timer : 9, programmed : 50000, actual : 50014
Timer : 10, programmed : 55000, actual : 55019
Timer : 11, programmed : 60000, actual : 60016
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 70376, Dms : 10062
Timer : 0, programmed : 5000, actual : 5006
Timer : 1, programmed : 10000, actual : 10003
Timer : 2, programmed : 15000, actual : 14999
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 24994
Timer : 5, programmed : 30000, actual : 29999
Timer : 6, programmed : 35000, actual : 35005
Timer : 7, programmed : 40000, actual : 40019
Timer : 8, programmed : 45000, actual : 45017
Timer : 9, programmed : 50000, actual : 50014
Timer : 10, programmed : 55000, actual : 55019
Timer : 11, programmed : 60000, actual : 60016
Timer : 12, programmed : 65000, actual : 65013
Timer : 13, programmed : 70000, actual : 70019
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
SimpleTimer : 2, ms : 80439, Dms : 10063
Timer : 0, programmed : 5000, actual : 4997
Timer : 1, programmed : 10000, actual : 9994
Timer : 2, programmed : 15000, actual : 15000
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 25002
Timer : 5, programmed : 30000, actual : 29999
Timer : 6, programmed : 35000, actual : 35005
Timer : 7, programmed : 40000, actual : 39994
Timer : 8, programmed : 45000, actual : 45017
Timer : 9, programmed : 50000, actual : 50014
Timer : 10, programmed : 55000, actual : 55019
Timer : 11, programmed : 60000, actual : 60016
Timer : 12, programmed : 65000, actual : 65013
Timer : 13, programmed : 70000, actual : 70019
Timer : 14, programmed : 75000, actual : 75016
Timer : 15, programmed : 80000, actual : 80013
Good Luck,
from megaavr_timerinterrupt.
wcwuttke
commented on June 12, 2024
Hello,
I need a 1 millisecond timer. That can only be done with the 250 KHz clock.
According to the formula, the correct value gets stored in TCB1_CCMP
(250) for a 1 ms timer. However, the timer interval is 2 ms. I made a workaround
by changing TCB1_CCMP in my code. Now I have interrupts occurring at
precise 1 ms intervals (as measured with my oscilloscope). It behaves as if the
250 KHz clock has been divided by two somewhere.
Bill Wuttke
from megaavr_timerinterrupt.
khoih-prog
commented on June 12, 2024
Good to know it's OK for you.
It behaves as if the 250 KHz clock has been divided by two somewhere.
I actually haven't tested with 250KHz. Possibly a bug somewhere in this library, or the core???
I'll spend some time to investigate later whenever I have time. I'd appreciate it you could help here to locate the issue.
Regards,
from megaavr_timerinterrupt.
wcwuttke
commented on June 12, 2024
Hello Khoi,
I'll be investigating further tomorrow. It's been a long time since I've played around with registers, etc.,
and then it was on 6800 & Z80s. Things have changed alot since then. Anyhow, I'll try to do
some register manipulation to get a basic timer going so I can do a comparison. I'll let
you know what I find.
Regards,
Bil Wuttke
On Sunday, September 5, 2021, 07:09:51 PM PDT, Khoi Hoang ***@***.***> wrote:
Good to know it's OK for you.
It behaves as if the 250 KHz clock has been divided by two somewhere.
I actually haven't tested with 250KHz. Possibly a bug somewhere in this library, or the core???
I'll spend some time to investigate later whenever I have time. I'd appreciate it you could help here to locate the issue.
Regards,
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from megaavr_timerinterrupt.
wcwuttke
commented on June 12, 2024
Hello Khoi,
I wrote two test sketches today, one for TCA, and one for TCB, using direct register manipulation.
Both work correctly, delivering 1 millisecond interrupts using sys_clk/64. Both are attached.
(Although the TCB timing is a little "glitchy" on the oscilloscope.) The TCB code probably
has an error or two.
Regards,
Bill Wuttke
//**************************************************************************************************
//**************************************************************************************************
// TCA Timer Test Sketch. 1 millisecond timer.
// modified from Microchip TB3217 example 7-1
#define PERIOD_EXAMPLE_VALUE (249) /* 1 millisecond using sys_clk/64 */
void TCA0_init(void)
{
/* enable overflow interrupt */
TCA0.SINGLE.INTCTRL = TCA_SINGLE_OVF_bm;
/* set Normal mode */
TCA0.SINGLE.CTRLB = TCA_SINGLE_WGMODE_NORMAL_gc;
/* disable event counting */
TCA0.SINGLE.EVCTRL &= ~(TCA_SINGLE_CNTEI_bm);
/* set the period */
TCA0.SINGLE.PER = PERIOD_EXAMPLE_VALUE;
TCA0.SINGLE.CTRLA = TCA_SINGLE_CLKSEL_DIV64_gc /* set clock source (sys_clk/64) */
| TCA_SINGLE_ENABLE_bm; /* start timer */
}
void PORT_init(void)
{
/* set pin 0 of PORT A as output */
pinMode(A0, OUTPUT);
}
ISR(TCA0_OVF_vect)
{
static bool toggle1 = false;
/* Toggle PIN 0 of PORT A */
digitalWrite(A0, toggle1);
toggle1 = !toggle1;
/* The interrupt flag has to be cleared manually */
TCA0.SINGLE.INTFLAGS = TCA_SINGLE_OVF_bm;
}
void setup() {
PORT_init();
TCA0_init();
/* enable global interrupts */
sei();
}
void loop() {
}
//**************************************************************************************************
//**************************************************************************************************
// TCB Timer Test Sketch. 1 millisecond timer.
#define PERIOD_EXAMPLE_VALUE (250) /* 1 millisecond using sys_clk/64 */
void CLOCK_init (void)
{
/* Enable writing to protected register */
CPU_CCP = CCP_IOREG_gc;
/* Enable Prescaler and set Prescaler Division to 64 */
CLKCTRL.MCLKCTRLB = CLKCTRL_PDIV_64X_gc | CLKCTRL_PEN_bm;
/* Enable writing to protected register */
CPU_CCP = CCP_IOREG_gc;
/* Select OSC20M */
CLKCTRL.MCLKCTRLA = CLKCTRL_CLKSEL_OSC20M_gc;
/* Wait for system oscillator changing to finish */
while (CLKCTRL.MCLKSTATUS & CLKCTRL_SOSC_bm)
{
;
}
}
void TCB1_init(void)
{
/* Load the Compare or Capture register with the timeout value*/
TCB1.CCMPL = PERIOD_EXAMPLE_VALUE;
TCB1.CCMPH = 0;
/* Enable TCB and set CLK_PER divider to 1 (No Prescaling) */
TCB1.CTRLA = TCB_CLKSEL_CLKDIV1_gc | TCB_ENABLE_bm;
/* Configure TCB in Periodic Timeout mode */
TCB1.CTRLB = TCB_CCMPEN_bm;
/* Enable Capture or Timeout interrupt */
TCB1.INTCTRL = TCB_CAPT_bm;
}
void PORT_init (void)
{
/* set pin 0 of PORT A as output */
pinMode(A0, OUTPUT);
}
ISR(TCB1_INT_vect)
{
static bool toggle1 = false;
/* Toggle PIN 0 of PORT A */
digitalWrite(A0, toggle1);
toggle1 = !toggle1;
/* The interrupt flag has to be cleared manually */
TCB1.INTFLAGS = TCB_CAPT_bm; /* Clear the interrupt flag */
}
void setup() {
CLOCK_init();
PORT_init();
TCB1_init();
sei();
}
void loop() {
}
On Sunday, September 5, 2021, 07:09:51 PM PDT, Khoi Hoang ***@***.***> wrote:
Good to know it's OK for you.
It behaves as if the 250 KHz clock has been divided by two somewhere.
I actually haven't tested with 250KHz. Possibly a bug somewhere in this library, or the core???
I'll spend some time to investigate later whenever I have time. I'd appreciate it you could help here to locate the issue.
Regards,
—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub, or unsubscribe.
Triage notifications on the go with GitHub Mobile for iOS or Android.
from megaavr_timerinterrupt.
khoih-prog
commented on June 12, 2024
Thanks Bill,
The TCB code probably has an error or two.
Do you mean error in the library? I believe so.. Could you please help locate and make a PR ?
If not possible due to time constraint, it's OK and I understand and will fix it later.
I'm reopening the issue now
Best Regards,
Khoi
from megaavr_timerinterrupt.
wcwuttke
commented on June 12, 2024
Hello Khoi,
I've been trying to locate the problem - it looks like you set the timer registers correctly.
It looks like you are not using the interrupt directly, but do something with counts - that's
where I get lost.
I am totally unfamiliar with the workings of Github, except that it stores one of my projects.
Therefore, I'll leave the PR, etc, for you.
My immediate problem (need for 1 ms timer) has been solved by using a few lines of code to
set the timer registers.
Best Regards,
Bill Wuttke
On Monday, September 6, 2021, 01:51:10 PM PDT, Khoi Hoang ***@***.***> wrote:
Thanks Bill,
The TCB code probably has an error or two.
Do you mean error in the library? I believe so.. Could you please help locate and make a PR ?
If not possible due to time constraint, it's OK and I understand and will fix it later.
I'm reopening the issue now
Best Regards,
Khoi
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from megaavr_timerinterrupt.
khoih-prog
commented on June 12, 2024
Hi Bill,
Thanks. I'll spend some time later to investigate, locate and solve this issue.
Regards,
from megaavr_timerinterrupt.
khoih-prog
commented on June 12, 2024
Hi @wcwuttke
I'm sorry to wait too long to fix the bug, which is delicate and hard-to-find and happened only to high frequencies (around >245Hz). The bug has just been fixed by the new megaAVR_TimerInterrupt releases v1.4.0
Your contribution is noted in Contributions and Thanks
Regards,
Release v1.4.0
- Fix TCB Clock bug in high frequencies. Check Interrupt interval 2X requested interval #1
- Add example to demo High Frequency
- Delete Blynk-related examples
- Add changelog.md
from megaavr_timerinterrupt.
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