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Unread 04-05-2012, 18:56
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Re: TI and future Jaguars

Quote:
Originally Posted by dsirovica View Post
The modules are:
1. Power Mosfets
2. H-Bridge driver
3. CPU for fancy stuff and coms
4. Brown-out support (supercap etc that could be in a separate module)
5. on-board indicators (if desired)
6. Thermal management (for higher power systems, bigger fan, heatsinks, etc.)

In reality 1 & 2 would be one module (that is the Sparkfun link above).
3 - 5 would be the second module.
6 may be a selection of fans.
Do not forget these probably need to be on the high power section or somehow optional to it:
A. Current monitor / voltage monitor.
B. Reverse voltage protection (optional and removable).
C. High side supply (driver could mean 2 different things)...please let's not use P-Channel MOSFETs for the high side.
D. Someway to identify what you just connected to the interface module.

Also we could use a SuperCap, or we could use battery backed static RAM, or just make sure it has a separate power supply interface for the interface module and the power module (let them find a battery to keep the interface module alive or take their chances).

Quote:
Have you seen the Raspberry Pi - a $30 Linux PC! that could give Stellaris a run for its money as the CPU module. Though we need an RTOS, but there probably is an open source RTOS that could be ported.
The Raspberry Pi's prime interest to me is the very low cost. Other than that Gumstix, Cotton Candy, BeagleBoards and Pandaboards interest me as well. Along with the stuff at FriendlyARM.

Keep in mind also the Parallax Propeller is 8 processor (they call them COGs) each at 20MIPS microcontroller in a single chip with shared memory. That's 8 things you can do without sharing, scheduling or messing around. My current electronic motor control abused this nicely (why interrupt the processor for the CAN communications, just dump the adjustment data in the shared RAM and let the other processor pull it up when it's ready...no timing issues with flags and semaphores).

Quote:
The problem we have is the lack of profits in this particular segment that would drive anyone to produce a Jag killer.
Given I'm offering to help offset the costs for a near production prototype, not really looking for an owner as much as contributors. They contribute a little here and there and then when it comes time for production they can use it as well. As demand grows for it, eventually we can start KOPing them if FIRST desires. At that point FIRST might chip in. In the mean time I won't object to people making them or having them made for them on an as need basis.

Quote:
Maybe paying $150 per motor controller is not all bad if they don't break and we get to reuse them over many seasons...
I think honestly we can make a PWM interface module and power module for less than or around $100 in small quantity.

The CAN modules? Pushing it a bit. Probably not with the Stellaris. Microchip PICs can do it. Atmel AVRs all the way to the XMega with some fiddling. The ColdFire 68k stuff no problem (even CAN2). The Parallax Propeller is a bit of a hack but it works.

Quote:
BTW: I talked to a few teams that use other processors in addition to the cRio, and I was told the only thing FIRST cares about is that you run each motor control throughthe cRio so they can shut it down for safety. Otherwise you can mount a Cray on each tetacle of the robot. Is that so?
Not entirely. Team 11 of whom I am one of the programming mentors did in point of fact field an AMD X2 dual core netbook on our robot this year. It was a full blown system without the display attached (I'll never see those tiny screws again BTW). It had an 32GB SSD. It was *just* under the $400 restriction. We connected it's ethernet port to the D-Link AP and used sockets to talk to Java in the cRIO with Java on the laptop (the students wrote a video processing application basically from scratch that used Video4Linux actually quite interesting). We did use the battery for the unit and all of that was legal and approved for field use at 2 competitions. We did remove the unit towards the end competition outings because of unrelated issues to what the driver's needed. It was connected to 2 USB cameras. One was 1080P resolution and slow frame rate. The other was VGA resolution and high frame rate (more than 30fps). It ran Ubuntu Linux.

The big trick was that it added weight to the robot (3lbs for the netbook) and no matter what anyone said including the Q&A last year I was very concerned we were gonna get told no at the inspections. Turned out great, just needed proof of cost.

I'll also point out again. If we endeavor to make the 'custom circuit module' the FIRST field shutdowns and limits would be honored by that middle module. A person could, if FIRST approves all that, take a laptop put a Parallax Propeller on a single PCB (they are usually used with USB for programming and debugging), make that PCB have places for 6 or 7 'custom interface modules' and then put 6 or 7 power modules on that. That would make one brain out of the laptop, with a USB interface to 6 or 7 electronic motor controls. Again you could do that technically that is all uncharted territory for FIRST to decide on. However for the hobby person they could remove the custom interface module and have essentially a single unit with a USB connector and places to connect 6 or 7 CIM size motors...just do some packaging. It's possible to make the entire control system for a FIRST size robot the size of a kid's lunchbox like that. (Just remember that something still needs to trigger the 'custom circuit modules' safety controls...so there would need to be something from FIRST to do that, software or hardware somewhere...but outside of FIRST...no such issue and no need for those middle modules).

Last edited by techhelpbb : 04-05-2012 at 19:28.
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