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  1. 20400 Here pin 5 is toggled with maximal rate in...

    20400
    Here pin 5 is toggled with maximal rate in the main routine. Always when interrupts happen the toggling stops. One sees the short gaps due to my interrupt routine. But there is also a lon gap...
  2. 20399 See the picture of my oscilloscope. The...

    20399
    See the picture of my oscilloscope. The upper blue trace is pin 7 and has a pulse if a gap is detected. The lower green trace is pin 5 and has a pulse for every interrupt. I would say that one...
  3. This is a program that shows missing interrupts....

    This is a program that shows missing interrupts. I connect pin5 and pin7 to my oscilloscope to see the pulses that are generated. The interrupt rate is 500000/second. The interruptroutine measures...
  4. interrupts missing at high rate ( 500k Interrupts/sec ) on Teensy 4.0

    I want a high interrupt rate of 500000 Interrupts/sec. There seem to be other interrupts that interfere with my interrupt routine ( I measure sometimes more than 2400 cycles between interrupts where...
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    A cache entry can be cleared and invalidated by:...

    A cache entry can be cleared and invalidated by:

    SCB_CACHE_DCCISW = (((sets << SCB_DCCISW_SET_Pos) & SCB_DCCISW_SET_Msk) | ((ways << SCB_DCCISW_WAY_Pos) & SCB_DCCISW_WAY_Msk) );

    Is there...
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    Cache demo seems to work now with a buffer in RAM2

    Cache demo seems to work now with a buffer in RAM2
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    That would mean that dynamically allocated...

    That would mean that dynamically allocated variables (via malloc) would need the cache, right?
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    Data cache demo on Teensy 4.0

    Is the data cache used on the Teensy 4.0 in a usual program for holding the data? Or is the on-chip RAM so fast that no data cache is used. How can I demonstrate that the data-cache is used. Is the...
  9. loop execution time with dual-issue disabled Teensy 4.0

    I am currently playing around with the Teens4.0 and want to understand its architectural behaviour. To inspect "dual issue" I created a program (listing complete below) that contains the following...
  10. SPEED and SlewRateEnable(SRE) setting on GPIO pin Teensy4.0

    I try to see the influence of the SPEED and SRE setting on an output. I use output pin 13 and have the following connections from this pin: 100 Ohm to +3V3, 100 Ohm to GND, 100 pF to GND. I don't see...
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    Slow clocking IGPIO-pin on Teensy 4.0

    I am currently playing with the various clocking options of the Teensy 4.0. Now I want to test the GPIO clocking and I am searching for an example where the GPIO-pin is slowly clocked and where that...
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    The crazy thing is: The code is working with 1MHz...

    The crazy thing is: The code is working with 1MHz if I put the PWM initialization behind the doStart() routine.
    So the following code is working:


    int LEDpin = 5 ;
    int PWMpin = 4 ;

    #include...
  13. Hi Paul, thanks a lot for your advice. I have put...

    Hi Paul, thanks a lot for your advice. I have put a call to "usb_serial_putchar(c) ;" into "putchar_debug(char c)". That seems to work!
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    Teensy 4.0 using TeensyDuino 1.51 . Changing the...

    Teensy 4.0 using TeensyDuino 1.51 .
    Changing the PWM pin did not change anything.
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    maximum frequency for timer triggered ADC

    I have used the timer_adc example code to write the code given below. I want to sample the ADC with high frequency and output its value via pwm. The code works if I use 500kHz as trigger rate. I can...
  16. debug printing using Serial.printf in pwm.c on Teensy 4

    I am currently trying to understand how various core routines on the T4 work. I want do insert printing commands (Serial.printf(...)) into the pwm.c routine. I dont get the routine linked. How can I...
  17. Thread: ADC in AUDIO tool

    by ossi
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    I am asking for a documentation of the...

    I am asking for a documentation of the blocks/functions contained in the library. There seems to be a MQS functionality included in the lib but not in the GUI. Is that somewhere documented?
  18. Thread: ADC in AUDIO tool

    by ossi
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    ADC in AUDIO tool

    Is it right that the ADC (AudioInputAnalog ) is not included in the current version of the AUDIO library for Teensy 4.0? Has someone found a way to use the ADC for sampling with the AUDIO tool? Where...
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    A keeper can be used to preserve the pin...

    A keeper can be used to preserve the pin output-state when the pin driver is switched off. Further info can be obtained by the app-note:
    ...
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    @manitou Many thanks for your help. I think your...

    @manitou Many thanks for your help. I think your program will provide a good starting point for my project.
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    MQS on the Teensy 4.0

    Is there someone having experience with the MQS feature of the Teensy 4.0?
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    With the line: ...

    With the line:


    IOMUXC_SW_PAD_CTL_PAD_GPIO_AD_B1_02 &= ~ (1<<12) ; // disable keeper

    I could switch off the keeper at a0. The input current was so small that I couldn't measure it in this...
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    In my case I should have used: pinMode(PIN_A0,...

    In my case I should have used:
    pinMode(PIN_A0, INPUT);
    This disables the keeper. Nevertheless I think it would be good to disable keepers at startup.
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    Teensy 4.0 ADC keeper issue

    I used the program given below to read an analog voltage on pin 14/A0. I observed strange values and it took me some hours to learn that the keeper on this pin is enabled and leads to a current...
  25. I have checked the option bits for the ADC. The...

    I have checked the option bits for the ADC. The Teensy 4.0 seems to enable "Low Power Mode" if nothing special is done.
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    In the datasheet the pin GPIO_AD_B1_02 is...

    In the datasheet the pin GPIO_AD_B1_02 is mentioned in the ADC chapter whereas GPIO_AD_B0_02 is not. In the datasheet I don't find a way to connect pin 0 with the ADC.
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    As far as I understand the Teensy 4.0 pinout pins...

    As far as I understand the Teensy 4.0 pinout pins 0 and 1 can not be connected to the ADCs. You must use a pin with an Axx designation.
  28. If low-power mode is enabled it should be checked...

    If low-power mode is enabled it should be checked whether this is compatible with high-speed mode.
  29. Teensy 4.0 wrong register in cores analog.c ?

    In the Teensy 4.0 cores file analog.c is the following line:
    ADC1_CFG = mode | ADC_HC_AIEN | ADC_CFG_ADHSC;
    As far as I understand the register ADC1_CFG gets initialized here. But the bit...
  30. Teensy 4.0: check for interrupts enabled, readin PRIMASK

    Is there a method to check wether interrupts are enabled? I think it would be necessary to read the PRIMASK register. Can I read that in a simple way? How would I use the corresponding CMSIS function?
  31. @Paul: I am currently playing with FLEXIO and...

    @Paul: I am currently playing with FLEXIO and FLEXPWM. With FLEXPWM I am quite through. With FLEXIO I am at the beginning. Thanks for the info about NanoEdge. I could not find it because I used the...
  32. "FLEXIO" units and "NanoEdge placer block" on Teensy 4.0

    In the datasheet it is said that the IMXRT1060 has 3 FLEXIO units. But when I try to access FLEXIO1 and FLEXIO2 my program crashes. Access to FLEXIO3 works. In the PWM unit the datasheet says that a...
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    @Paul: I want to generate signals as fast as...

    @Paul: I want to generate signals as fast as possible. The CPU has no other work to do after the parameters have been setup. Of course you are right that normally fast interruopts should be avoided....
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    IntervalTimer faster than 2us on Teensy 4.0

    The highest interrupt rate using a IntervalTimer is (as far as I know) 500000 interrupts/second. Is there a possibility to get a higher rate, perhaps by clocking the timer faster?
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    Thanks for your help! Now I have the info I...

    Thanks for your help! Now I have the info I needed.
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    ADC async clock generation Teensy 4.0

    The Teensy 4.0 cpu datasheet claims to have a "Asynchronous clock source for lower noise operation with option to output the clock". I can not find this clock source described in the datasheet. Does...
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    Hi Paul, thanks for your hints. Momentarily I am...

    Hi Paul, thanks for your hints. Momentarily I am trying to understand the clocking and sampling of the ADC. Is it right that changing the CPU clock speed will also change the clock conversion time?
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    Clock generation unit on Teensy 4.0

    I currently look into the clock generation unit of the Teensy 4.0. I want to know how this works, but its very very complex. Are there anywhere examples how to set the various options? Has someone...
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    ADC calibration on Teensy 4.0

    The datasheet of the Teensy 4.0 CPU recommands an ADC calibration before using the ADC. Does the Teensy do this calibration?
  40. Teensy 4.0 GPIO Output options: drive,speed,slewrate

    I am currently playing withe the output options of pin 5 of the Teensy 4.0 board. I can change the drive-strength. But when I try to change speed or slew-rate I see no influence on the waveform at...
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    The effect can be demonstrated using the...

    The effect can be demonstrated using the following program without attaching an oscilloscope to the LEDpin. It gives the loop-execution time that changes with switching a line on and off.


    ...
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    Disable instruction cache on Teensy 4.0

    I wanted a program that demonstrates cache influence. To demonstrate behaviour without caching I put the program into FLASHMEM and disable the instruction cache with a routine I found in...
  43. testing data- and instruction-cache on the Teensy 4.0

    I want to test wich influence caching has on the Teensy 4.0. I use the following routine (taken from CMSIS) to disable caches:



    // from core_cm7.h (CMSIS)
    #if defined(__IMXRT1062__)
    #define...
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    Interesting loop timing on Teensy 4.0

    To get an insight into the inner working of the Teensy 4.0 I have attached an oscilloskope to the LEDpin. Now I let the following program run, where I want to understand what happens in the inner...
  45. Can someone tell me how to disable the...

    Can someone tell me how to disable the instruction cache? I think Frank B. comes close to it in his measure concept.
    As far as I understand now I should invalidate the I-cache by
    ...
  46. Seems a lot of discussion took place yesterday...

    Seems a lot of discussion took place yesterday late in the evening when I was not online. Thank you all for your contributions. Exact execution timing seems to be very difficult on this high power...
  47. Can you explain the runtime of this simple Teensy4 loop?

    I am just playing around with the Teensy 4.0 and try to understand how it works. I am currently executing the following program:



    int led = 13;

    void setup() {
    pinMode(led, OUTPUT);
    ...
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    I now observe printf errors also on the teensy...

    I now observe printf errors also on the teensy 4.0 running at 100MHz
  49. @Paul: Your barrier seems to work. Thanks! Thank...

    @Paul: Your barrier seems to work. Thanks!
    Thank you also for the Teensy boards (especially 4.0)! They have incredible power and Arduino-compatibility makes the start easy.
  50. using micros() for execution time measurment, can it get "out of order executed"

    I am using the micros() function to measure the timing of software blocks:


    start=micros()
    codeblock
    stop=micros()
    executionTime=stop-start

    Is it possible that the compiler changes the...
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