Cortex Guts

VEX V5 General Discussion Technical Discussion
#1

So I decided to open up a cortex that I had at home (because, why not) and I found it interesting that there are a bunch of unused ports between motor port 1 and the UART and I2C ports:
http://botsnstuff.com/w/images/thumb/4/46/Cortex_Guts_1.jpg/800px-Cortex_Guts_1.jpg

My guess is that it was just cheaper to use the same plastic piece on both sides but that the extra ports can’t actually do anything.

The cortex also has 2 usb ports which I find odd:
http://botsnstuff.com/w/images/thumb/0/02/Cortex_Guts_2.jpg/800px-Cortex_Guts_2.jpg

Anybody know why these things are?

JSUK, the controller is Rev# NC2 (although the case originally said 1 and somebody sharpied over the 1). Perhaps other revisions are different?

#2

Obviously, but those details really are off limits.

#3

Basically, you can’t handle the truth. To the 33 sec mark should cut it…

On the lower picture, I presume the two processors are the master and user CPUs?

#4

My guess is that if the extra ports do anything, they are for testing at the factory.

#5

I figured as much :stuck_out_tongue:

The one on the left is the STM32, so the user processor. Toward the center is an NXP LPC2458, in my case, which I would guess is the master. The specs sheet list of features definitely matches the cortex’s capabilities.

Oh I guess probably, that does seem to be about where James plugged in his JTAG Debugger. He pointed out that he pixelated it because he doesn’t want us to know exactly how it’s setup, hence the off-limit details :).

#6

Huh… the cortex has two usb ports… I wonder if both are connected…

#7

I just tried plugging the bottom one in (using a USB extension cable since the VexNET key doesn’t fit directly) and nothing. Probably just a cheap way to raise the height of the USB port to what they wanted.

#8

On the original cortex (NC1 etc) it always looked like the USB was connected, ie. there were traces on the board, I always hoped it went the the user processor but…

On the newer units (A3, A4 etc.), the ones with the hump, things changed inside.

Only one port now.

Daniel, be careful just plugging things in unless you can afford to damage the board. Just because there was a hidden USB port doesn’t mean that it was electrically compatible with USB.

#9

Perhaps it does go somewhere - VexNET didn’t work and plugging it into a computer doesn’t make any lights turn on, but that doesn’t mean it’s not doing something.

The hump seems like such a waste of space! I always thought there was like a good reason, now I see that they just pushed the USB port higher :stuck_out_tongue:

Thanks for the heads up - I’ll be more careful in the future.

#10

There was a reason, improved VEXnet performance (or less interference with the parts on the board or something like that), no one has ever shared the details but that’s what I understand.

#11

Probably shielding continuity since the stacked USB connector’s pins break out at the main PCB plane rather than up that horrible riser PCB which also somewhat undesirably adds multiple connection points between the socket and main PCB.

#12