PaulStoffregen
Well-known member
I can't seem to find the max GPIO sink/source current???
I don't know the official spec, but I can tell you I've "experimentally" seen ~60 mA into a dead short.
Most interesting is, in the chapter about the seven PLLs (Reference Manual) they say the CHIP is capable of running with 1 GHz.
Where did you see that?
Like we have now on Teensy 3.x, the PLLs (usually) run at much higher frequency than the CPU and get divided down by various factors to make the actual CPU clock.
For example, in the K66 the PLL gets divided by 2 (which isn't configurable) so we're actually running the PLL at 360 MHz on Teensy 3.6 when the CPU runs at 180 MHz.
All the info I've seen so far is PLL1 officially runs between 648 to 1296 MHz. The maximum (beyond spec) configurable PLL speed seems to be 1524 MHz. Unlike Kinetis, we get quite a playground of configurable stuff in this chip. The divider right after the PLL ("ARM_PODF") defaults to div-by-2, but supposedly can be set from 1 to 8. There's one more divider ("AHB_PODF") in the path, also configurable from 1 to 8. So if the chip really works with these both in div-by-1 mode, overclocking all the way up to 1.525 GHz might be possible to at least try.
If that first divider really needs to be div-by-2 (maybe for a 50% duty cycle?) then we may be limited to attempting only up to 762 MHz.
However, the other really unfortunate overclocking problem is the IPG_PODF divider can be at most div-by-4. The IPG clock is pretty much the same as F_BUS we have on Teensy 3.x... all the peripherals use it, at least for access to their registers. The official spec is 150 MHz max. Whether this will impose an upper limit on overclocking is a good question?
But let's not talk about overclocking now Its just an interesting information, now.( And I fear we had to increase the core-voltage, which may be a bit risky)
Sure, why not talk of overclocking?! It's fun.
And yeah, pushing the core voltage up to 1.5V seems pretty risky...
I must admit, so far I've been doing pretty everything at 396 MHz, with the expectation it'll scale up or down. The RT1062 runs a little warm at this speed... so with extreme overclocking we might need heatsinks or other cooling.