SITCore / Duino electrical characteristics/max ratings?

Hi all,

(My first post on the GHI forum :slight_smile:
My Duino arrived and it’s great. But I’ve looked everywhere but can’t find any electrical characteristics of the SITcore chips and/or SBC modules.
Q. Is there a detailed technical document somewhere or should I use the ARM Cortex M7 documentation (3500 pages)?

For example, I need to know things like:

  • What’s the maximum safe load on a single output? in mA
  • What’s the maximum total load on all outputs?
  • What’s the max voltage on an input? Do they support 5v TTL?
  • Do all inputs/outputs have the same ratings?
  • What kind of protection is there on the SITcore chip for the outputs/inputs (over-voltage, current limiting, ESD protection diodes, etc)?
  • How much power is available for the 5V and 3V3 pins? (800mA - 205mA?) How does WiFi on/off affect it?

Matt

All good questions and should be documented. I will get back to you shortly with all details. Are you building something specific or just having fun with C#?

Welcome to the community.

I think its the same as with the rest, 20mA per pin, 200mA per mcu, it is 5V tolerant i can tell you that as ive tried myself, no protection and don’t source directly through mcu.

The chip: It is 20mA per pin, 140mA total on all pins, 5v tolerant.
The Duino: has 800mA regulator. If you run from 5V then you can get you 200mA for your own circuit but if you have higher voltage, like 9V then you will face heat issues on the regulator. This also depends on if you are using the WiFi or not.

I’m designing an “electron tube tester”, to test vacuum tubes and plot their characteristics. This is so I can get back into switch-mode power supply design and analog electronic design again (I’ve been mostly writing software/firmware most for the last 20 years).
It will have two 0…600v power supplies for the anode and screen grid, one 0.50v power supply for the heaters, and one -ve voltage signal generator for the grid (sine/ramp/sawtooth).
I’m using the Duino to handle USB communications to the control and UI application running on a PC; to control the switchers (an intelligent feedback loop using Duino code to replace a lot of circuitry); and for SPI communications with the high-accuracy current and voltage sensors on the PSUs.
Maybe I’ll try to market it. It will be good for modern HiFi and guitar amp valves too, matching etc.
Hours of fun.

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Maybe more detailed electrical specs would be nice…
On the tutorials page it says 8mA per pin (not 20mA) https://docs.ghielectronics.com/software/tinyclr/tutorials/gpio.html
Anyway, I’ll probably stick in a buffer chip just to be safe. (But the opto-isolated power MOSFET driver chip did not blow it up when I connected it directly :slight_smile:
Also, what’s the impedance of the analogue inputs? For example, if they are “sample and hold” type inputs, then they probably need low impedance connections, else they could give inaccurate readings.
… I’ll get my coat.

Hey @Greg_Norris this is a software tutorial and should not have current info. I am going to delete the note about 8mA. But didn’t you add the limits on chipset page? I can’t find it.

Hi Gus - I think this info does belong on the tutorials page - in big red letters (unless you want the beginners [like me] to blow up their boards :skull:).

The tutorial is for TinyCLR and not should buy cover board specific to hardware. Each board has its own limitations.

… but don’t the chips have the same characteristics?

no, even if some could have same characteristics

Chips begging used at this very moment, yes correct. But what happens when we add a chip from a complete different family with different characteristics in the future?