Teensy 3.5/3.6 overclocking

Does it make sense to passively heatsink the CPU on these for even more overclocking potential beyond 96 MHz (e.g., Arctic Silver + a heatsink stolen from an old video card)? Is it even possible to overclock beyond what Teensyduino supports?

Edit: I meant 240 Mhz for the 3.6...

If you check the files there are other CPU speed options commented out but they start breaking peripherals - wrong - see below. Believe the speed limit is not so much heat as glitches between the high and low speed parts of the CPU even at room temperature.

So if you wind the speed up it's a case of working out what components you can afford to loose control of, and then work out what you can achieve with the peripherals you do need (see problems they hit getting EEPROM to work)

edit - checked boards.txt and we are using all current clock configurations so disregard that bit.

If chasing performance edges suggest check of the K66 manual and what clock settings it can actually accept, searching for the registers mentioned in boards.txt.

A heat sink probably won't help.

The main overclocking limit is the max 8:1 ratio for the clock dividers, coupled with limited overclocking ability of the flash memory.

If you want to try extreme overclocking, you'd probably need to set up a very different build where everything runs only from RAM. You'd need to edit the linker script. You'd also need to write different startup code to copy the program image to RAM and the jump to it, before finishing the clock setup.

Only the portion of RAM below 0x20000000 allows fast code execution, so your code would need to be limited to under 64K.

SharpEars, do you have a Teensy ?

Frank B said:

SharpEars, do you have a Teensy ?

Click to expand...

I have both a 3.2 and a 3.6. I just finished soldering the pins on the 3.6 and wanted to get info on max performance to see how I can use it for my needs.

In fact, you commented on my pics of the 3.6 in: Teensy 3.6 ultra high-res high quality photos

sorry.
I wondered why you asked.. never touched the Teensy when it runs ?

Frank was it one of your Beta units that seemed to show failure somewhere over 200MHz? I've run mine at 240 Mhz regularly with no issues. And they don't get very warm - under 105°F.

The OP is confusing as it says: Teensy 3.5/3.6 overclocking and asks about 96 MHz. The T_3.6 spec is 180 and the T_3.5 is 120.

Though I'm not sure I've ever seen a T_3.5 run over 120 MHz for me - not that I tried much except on the Beta unit minimally where it froze after upload.

No, it (3.6) works great with 240MHz.
But..I2S/Audioshield with >192 MHz....for me..not
I hope we can solve that.

All my 3.2 work great with 144MHz without issues. Paul mentioned some users reported problems after some hours/days/weeks - i have a 3.2 running @144 for half a year now - just for fun .)
Perhaps the users who reported that problems have bugs in their sketches ? memoryleaks ?