G120 Analog Input4, P1_30 (Pin 59)

NETMF & Gadgeteer
1

Received my custom board based on G120 SOM last Friday.

Turns out the 600VAC input circuitry outputs an analog value, instead of a digital value …oops. So, I need to hook this circuit to an analog input instead of a digital input as I had initially planned.

Anyway I have used up all G120 Analogs with the exception of Analog 4, P1_30 (Pin 59).
I avoided this input on initial design because of user manual note below:

  • Pin 59 P1_30 AD4/COM4 OE must NOT be grounded on power-up for GHI Bootloader to function correctly.

Does this mean AI4 is totally worthless?
Perhaps it means as long as the input is floating (could be floating at 0V) and not wired to ground everything works fine???

Anybody know “EXACTLY” what the note is saying?

Anybody use Analog 4…any problems?

2

Maybe add assume circuitry to set the pin high on power up, like an op amp. Also, this effects the GHI loader, not the firmware. You can add a jumper if you ever needed the GHI loader after production.

3

Gus -

Prefer to not add circuitry…

Not sure I understand what you mean in your statement:
“Also, this effects the GHI loader, not the firmware. You can add a jumper if you ever needed the GHI loader after production.”

My understanding is that, the GHI bootloader is ALWAYS required…production…debug…whatever?

The documentation (the G120 SOM user manual) say’s:
GHI bootloader…blah…blah & executes TinyBooter
TinyBooter…blah…blah loads the firmware.
The firmware executes my application.

Perhaps you are saying that the P1_30 pin cannot be grounded on power-up if one plans on sending commands to the GHI boot loader?

4

@ mhardy - GHI loader is only needed to update tinybooter. Not much beside that.

5

So, if P1_30 is grounded on power-up, my application will execute, all AOK, correct?

Only if I want to update TinyBooter, for some reason, will I need to make sure that P1_30 is NOT grounded, correct?

6

@ mhardy - correct and I will double check.

7

Gus -

Yes, please double-check!

It is critical that we know EXACTLY what to expect.

If we do not understand this correctly, it could totally Brick boards that we will send into the field.

8

Gus -

Have you had a chance to double check this yet?

9

@ mhardy - I have P1.30 Grounded and the Cobra II that I am using is booting as normal. I am able to ping the board and retrieve the device info.

You cannot enter GHI Bootloader to perform the update process if that pin is grounded upon power up or reset.

10

Thanks Aron,

I also grounded P1.30 and my app runs just fine!

I also connected via fez config (via usb) and was able to erase the app, update firmware and do other functions, that I have done in the past.

The only function that appears to not work is updating TinyBooter via fez config, and I would assume via the command line also…

So, I guess all I need to do is add a pogo pin to disconnect P1.30 from any circuitry in the event that I need to update TinyBooter.