Main Site Documentation

G30 Oscillator (resonator)


#1

What’s the deal with the two crystal symbols here on the G30 TH schematic?

Q1A and Q1B

Doesn’t it need a single 12mhz crystal resonator? If there’s two there, then what is the value on Q1A?

And Q1 = 32k right? That’s RTC required if you are using VBAT? And if you are not using VBAT you can use the two as GPIO pins?


#2

Yes only one is needed.

32.768khz

Yes pins can be used as gpios

You may want to use the datasheet to get more details. But please let us know if you have any other questions.


#3

Yes been referencing the datasheet. Just wanted to make sure there wasn’t a disconnect between my ears. :slight_smile:

Another question; datasheet indicates LDR0, LDR1, MODE are pulled high on startup - is this via an internal pullup I assume? What is the impedance of the pullup?


#4

Internal pull up, very weak. Exact details will be in the stm32 datasheet.


#5

Don’t rely on the weak pullup. Suggest you use one on your board to make sure. Nothing worse that designing your layout and later finding you need one. If you find during test that it is not needed, you can leave it unpopulated for final builds. For the small cost and piece of mind, I prefer to use a more solid pullup.