Documentation on connecting?

OpenMV Products
#1

I think it could be very helpful if there was a page in the documentation dedicated to physical connections. I know that we have the pinout diagram in the quick reference, and there are links to the schematic and datasheets for the components – which in theory is enough to figure out connections – but in practice it would be much more user-friendly to have the most relevant information explicitly stated right there.

I’m talking about things such as:

  • the voltage range for powering the board,
  • the current consumption (at least approximate),
  • the maximum current on the 3.3V out pin,
  • which pins are 5V-tolerant,
  • the voltage range of the ADC,
  • which pins are used by which shields,
  • mention that there are no pullups on the I2C lines,
  • no reverse voltage protection,
  • maximum current on the GPIO pins,
  • perhaps (if you have time) some examples of wiring the board to different devices over serial, I2C, SPI, etc.

I think that this could help a lot, and maybe even prevent some fried boards!

#2

No, you are totally right (there’s an infinite amount of things to do).

I can’t say when I’ll have this update however. But, I guess this would take priority over firmware. I’ll try to do this this weekend.

#3

One more important point:

  • Can we connect the USB cable while the board is being powered from another source through VIN?
#4

Yes, because VIN is OR’d with VBUS.

#5

Alright, I’ve updated the quick ref.

I didn’t know this but STM32 devices all have 5V tolerant I/O pins. Nice!

#6

Aweseome, that’s really helpful, thanks!

#7

Almost. The pins are only 5v tolerant when in a digital mode. When in analog mode, you shouldn’t exceed 3.3v

#8

Thanks, I didn’t know that one :slight_smile:

I’ll add that to the silkscreen along with the max voltage…

#9

Its worth double checking the processor datasheet.

On the '405, pins PA4 and PA5 are tagged as TTa which means 3.3 V tolerant I/O directly connected to ADC (so those 2 pins are not 5v tolerant, even in a digital mode).

The five volt tolerant pins are all tagged as FT in the datasheet (in the pin and ball definitions section).

#10

There’s a note that when in digital mode the PA5 pin is 5V tolerant. See the superscript note after the table.

#11

Yeah note 4 seems to be on all of the analog pins. And all it says is that FT=5v. But PA4 and PA5 are NOT FT. They’re TTa. It might be worth clarifying with an STM FE.

#12

Funny, I just got my fire-sale board and came over here and it’s full of micropythoners. :slight_smile:
(My micropython port is on hold until the guys pretty much add all the stuff I have done. When they finish I’ll get back to adding the things missing again).
I thought if I do much the same thing on the openmv it might be more useful.