Oh, right, on the board itself. The Discovery board has an 8MHz crystal, the Cerberus has a 12MHz. I understand now. The MCU itself is the same, just the crystal is different. One would need to ensure that the PLL was configured correctly for the particular crystal in use.
It strikes me that it should be possible to use either the HSI or LSI oscillator to get a pretty good estimate of the HSE oscillator’s frequency. Then, you could set the PLL multiplier appropriately?
Clock the PLL from the HSE (being careful to use a multiplier that would be safe at 12 MHz HSE), and clock the RTC from the LSI. Even better if you have an accurate LSE, because ST is careful to say that the internal oscillators aren’t terribly accurate.
Set up one of the 32-bit timers as count-up with a heavy-duty prescaler divider, so it won’t overflow anytime soon. Use the RTC to wait a few seconds, and look at the timer value.
From the current timer value, one ought to be able to estimate the speed of the timer, and using that knowledge plus the knowledge of prescaler values and the PLL configuration, one ought to be able to estimate the HSE speed accurately enough to know, at minimum, whether it’s closer to 8 MHz or 12 MHz, even without an accurate LSE oscillator.
Thanks to all who answer if is possible run Cerb40 FW on Discovery board. The easyest way is to change oscilator from 8MHz to 12MHz and we can direct run cerberus FW without modifications and do not need fix/change FW on every update… If Im right is oscilator placed near STM32F4 chip right or we must change both?
Have someone time&knoweledge to do this, test it and write tutorial?
The good thing is that both of these crystals are through hole so it is easy to upgrade. I am pretty sure it is the one closest to the mcu, but double check with the schematics.
I am going to try it for sure once the source code for port will be available.
I happen to have a 12Mhz crystal laying about and could try this on my STM32F4_Discovery board.
However, I don’t have any Cerberus FW to install so there’s no way to know if it works. I would of course be able to test with some native code but I guess the PLL-config startup code would have to be modified (?) and I’m not sure how to do that.
The other crystal I’m sure is for the STLINKv2 chip (which seems to me to merely be a special firmware loaded on an STM32F103).
I’d go with Architect however, and check the schematic, or at least follow the traces.
Note that once you’ve done this, you’ll need to change your startup code if you’re working with the chip natively. In my setup, for example (Atollic TrueSTUDIO), it sets that code up specifically for the STM32F4-Discovery, and if you change the hardware, it won’t be writing the correct code out anymore.
I would be very interested in having fun with FEZ Cerberus :D, but can you check if this module is already available for the EMEA Zone…I’m in France, and my local reseller (LEXTRONIC) does not have any reference…
From less than 2 weeks to little more than 3 weeks, generally. I don’t know why this takes so long time, though
I know GHI is preparing orders as fast as they can, so they aren’t the bottleneck. Maybe customs ? :think:
Customs is always the biggest culprit in international shipping delays. Often you’ll get the usual hold up 7-10 business days. Sometimes you’ll get lucky with a sort hold when you just happen to be in a batch ready to inspect. And on occasion there’s a big delay when your lot gets targeted for random thorough inspection which can double your wait time.
