Teensy 4.1 Flash clock frequency question

D

DeweyOxberger

Member
On the Teensy 4.1, at power up, what maximum clock freq on the Winbond chip (U3) should I expect to see?

I'm seeing 143.7 MHz and that seems out of spec.

Is there something I'm doing wrong here? What clock frequency are you seeing?

I'm using Teensyduino 1.57 with the 1.8.19 ide.

scope_1.png
 
To add more info: A Teensy 4.1, fresh out the bag (running blinky) shows a clock of 120 MHz.

If I then compile blinky on my system and download it the clock will bump up to 144 MHz.

So the main flash clock seems to be set too high in the latest Teensyduino/Teensy 4.1 libraries.
 
Is uint32_t FlexSPI_NOR_Config[128] in bootdata.c the data that is supposed to control this clock frequency?

If I'm interpreting the data correctly it's set to 8 = 133 MHz. If I set it to 7 I get 180 MHz. I am clearly lost on this. How do you set the freq of the flash clock?
 
Well, this traces down to a change in bootcode.c - with a little luck one of you has access to a nice scope and can confirm my findings. With the prior value (3) in the clock field the flash clocks at 120 MHz. With the new setting (8) it clocks at 144 MHz. These don't really match the docs - which is confusing.

Assuming I'm not making some simple error here, this produces a flash clock frequency that is over-clocking the winbond flash chip. I started down this path because a friend was reporting boot failures at 85C.

https://github.com/PaulStoffregen/cores/commit/c346fc36ed97dcaed2fa1d70626fbd80cf35586d

@PaulStoffregen what did I mess up here?

(edit) - I have no idea how to tag users in vBulletin, doh.
 
@PaulStoffregen reads the forum and will come across these posts.

The other way to document the issue would be to create an ISSUE or PR on the PJRC github sources with a link to this thread.

Perhaps posting a photo of the Scope connections to the Teensy so Paul can repeat the test and confirm the right pins/signals and methodology were tested.
 
No need for a github issue. I have this on my list to investigate. Probably won't get to it until late next week, as a better 1.58-beta2 for gcc 11.3.1 testing and other high priority things are in front of this. But it's definitely on my list, so I won't forget.
 
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