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Is the Teensy Arduino library threadsafe? If not, you would need to keep all your Arduino code in a single thread and use other threads for processing, using proper synchronisation primitives.

I usually do my initial circuit design using ICircuit, which can have a programmable Arduino as part of the circuit. It’s not a teensy so lacks the peripherals and performance, but allows good prototyping before committing to hardware: https://icircuitapp.com/

I’m a hug Teensy fan, I’ve used the 3.x and 4.x boards in loads of my hobby projects. But last month I got an ESP32 based board (Lilygo Display T3) and have totally fallen in love with FreeRTOS… hopefully we’ll see FreeRTOS fully supported on our favourite Teensy soon :-)

Fantastic, cheers guys! I’ve used Always used ARM M Cores, and when doing real time things, like UAVs, I’ve had to be really careful about trying to ensure things like interrupts were as deterministic as possible, and use plenty of watchdog timers etc… I’m just wondering if these things would...

Is anyone here able to explain with a simple bullet point summary, what the differences between the ARM M and R cores are? I understand that the M cores are for embedded microcontroller applications, and the R cores are intended for “Real-time” applications, but what features facilitate the...

Oh... STILL in alpha!? Many thanks for the link. Perhaps Paul would do well to migrate Teensy to PlatformIO and VSCode!

I’ve been pondering a move to PlatformIO and VSCode, though I do like the plug and play nature of the current Arduino (despite the sh*tty editor)... but lockdown has meant all my projects are on hold (as I’m having to do childcare), is there a Beta of Arduino Pro?

I’m genuinely not surprised by this! Perhaps Paul should be on the phone to the RaspberryPi foundation, we might see a TeensyPi based on an M4 variant :)

We obviously don’t know the “arrangements” that the RaspberryPi Foundation has with various organisations... but we do know that Eben Upton is a GPU designer at ARM, and they have VERY close links with both ARM and Broadcom... I expect some deal was reached, that might not be available to other...

It is a custom ASIC, I expect that includes the fab set up costs too... I bet that the quoted cost is probably for the development of several chips too...

Good point, I’m particularly happy with the Teensy USB support, another reason why I’m not giving up my Teensy 4 any time soon :-)

My gut feeling is that there will be a future RaspberryPi SBC which will have this chip uC integrated... possibly taking over the GPIO exposed on the board?

The RaspberryPi Pico has a few nice features: a) 2 cores (and an easy API to control them). b) Banked RAM, to allow parallel RAM access. c) PIO... I wish all microcontrollers had this. -edit- d) Low price... I won’t be giving up my Teensy 4 any time soon, I like 600Mhz of CPU headroom and...

Really helpful, cheers!

There really needs to be a good tutorial about using the XBar and DMA on the T4

Thank you for this!

This is fantastic! Hopefully it will spur more activity on the wiki!

Thanks for the link! I agree it seems sensible to use a community driven wiki to help improve the documentation rather than taking resources away from board/software development.

I think the scope of my project is too ambitious at this time. It’s a real struggle to switch the IO fast enough to generate the pixel data, not to mention the DA conversion... I’ve looking into using Shift registers like the 74HC595 and R2R DACs but this is increasingly drifting out of my...

Are you able to link to the API document that covers all these awesome little features I don’t know about? ;)

I’m also keen to try and DMA to the GPIO, but I think the T4 digital I/O pins don’t correspond to bits in a single register so can be written to with a single write. I’m not sure how useful DMA is with GPIO

No problem! I’m in the same situation. Teensy Timer Tool is really good already, thank you for your efforts. I look forward to any features you are able to add in future :)

I've avoided reading the technical documents until you linked to them, as these modern uCs are so complex it would take me weeks to understand how their peripherals work... I'll try and work out what registers do what... I like to use microcontrollers to interact with and emulate vintage...

Regarding VGA output on the Teensy4.0... I’m reading the CPU manual, and the chip seems to have Video generation hardware built in to the chip already. Perhaps someone more knowledgeable with these microcontrollers could have a look at chapter 35 and see how much, if any, this hardware might be...

If I’ve understood the document Luni linked, PLL4 and PLL5 generate pretty much any frequency, but how to use them as a clock source for interrupt generation?

A slightly different question: Can we be more flexible with the frequency of the clock source? That is to ask, do all the clocks need to be a multiple of the 24MHz master clock, or could I have a 151Mhz clock, for example?

Excellent! I’m glad my tests have been useful. I will be focusing my attention on the OneShotTimer next as I am curious to see if that might suit my needs better :)

Ok, setting the prescaler to 0 for TMR in the defaultConfig.h file results in both the expected output and accuracy :) I know we are bound to the Arduino platform limitations, perhaps there is an easier way to adjust the config?

I have put userConfig.h in the sketch folder, tried each prescaler value from 0 to 7... with a interval value of 0.636 (which should be a good value for a prescaler of 0)... all had no effect... I even tried to set the USE_GPT_PIT_150MHz = true, also no effect... so I don't think the compiler is...

Ok, First Test for a 2us pulse: #include "TeensyTimerTool.h" using namespace TeensyTimerTool; PeriodicTimer event(TMR1); int pin = 13; volatile int state = 0; void tRun(){ state = 1 - state; digitalWriteFast(pin, state); return; } void setup() { // put your setup code here, to...

Ok, so I have a question. I want a periodic interrupt around every 500ns... I have tried all the different timers and none seem to be suitable. I can post my code, but it is simple, it just toggles the pin 13 every call.

Thank you, this was the missing piece of the puzzle...

Hi KurtE, I have Arduino software installed and running fine with my Teensy 4.0... It's the TeensyTimerTool I'm having difficulty with... where should I install the src files?

Maybe I'm missing something, is there an official way to install this on the Mac version of the Arduino software?

How did I miss this?! I’ll be testing this tonight :D

If you have any free time have a read of this. http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node00AE.html The C64 and Amiga sprite systems are somewhat similar (though the Amiga’s Sprite system heritage is, amusingly, from the 8bit Atari line). What makes the Amiga really...

It took a huge amount of work just to get it this far... The Blitter is still missing a couple of modes, sprites aren’t emulated at all (except sprite 0, which is emulated outside of the DMA sequencer)... But it runs system friendly software well, and quite a few games amazingly work too!

You can find the source code here: https://github.com/h5n1xp/Omega

Hi Frank, thanks for sharing this, defragster has already pointed me to this thread. I love what you have done with integrating your C64 emu on the Teensy 3.6... As you can probably guess I have similar plans, now we have a microcontroller running at 600Mhz, I want to see if I can integrate...

How do we select a different clock source for the PIT?

I've finally managed to get something working, so I thought it would be a good idea to post my progress just in case it is of use to others. Theory The VGA display consists of 525 line of 800 pixels, updated every 16.6667ms. This means that each line is drawn within 31,777.30ns... dividing by...

I dug out my OScope, looking at the signals it seems I’m going to struggle to achieve even the graphical output of the ZX81 (64 by 48 black and white pixels) 😐

I phrased my reply poorly, I mean 24bits per pixel, 8bits per colour channel... the T3.6 VGA driver uses 2/3/3 bits per colour channel scheme, which would be far too limited for my project. I'll probably get a T4.1 anyway (I have a T3.6 here I haven't used yet)... it might be a better option.

Many thanks for this, after much reading it seems I have been rather optimistic as to driving a VGA display with 8bits per pixel, directly from the GPIO... Perhaps the larger form factor T4 might offer more options. Maybe 4bits per pixel would be doable, but that's not really where I want to go...

I'm currently working on Bit Banging a VGA display using a T4, defragster has already helped me out with the timing to get nanosecond accuracy... But while digitalWriteFast() seems to operate within a few cycles when setting the state of a single pin... But when setting multiple pins, it can...

Hi mlu, I want to use your code in an open source project (under the apache licence, if this is ok?), how do you want to be credited?

Perfect! Many thanks for providing this link, I need to run some tests to check it’s good on a Teensy 4, but otherwise this is exactly what I need.

Hi defragster, I guess I could write my own elapsednano() fucntion, which would check if the counter is less than the previous read value and handles the delta accordingly... But that is more heavyweight than I had hoped for... perhaps the T4 has a one shot timer based on the cycle counter...

Is it possible to reset the ARM DWT Cycle counter after reading it, so you don’t suffer an overflow?

Hi all, Has anyone used a Teeny 3.x GPIO to interface with an ISA bus? I want to be able to communicate with a RaspberryPI via SPI, but the only spare bus on the Amiga A1200 I want to use is an old 16Bit PCMCIA (basically a 16bit ISA expansion)... so I need to communicate with the Teensy via...