Jack Crossfire's blog View Details
Archive for December, 2013 - Page 2
Posted by Jack Crossfire | Dec 12, 2013 @ 05:55 AM | 4,115 Views
After much battling with 2 PICs, 2 boards, & the SDCC toolchain, the 8 bit PICs with SDCC clearly don't have the horsepower to do any significant math. They can't do the tilt compensation for a compass. It may be a compiler limitation or a stack limitation. Fixed point, 4x4 matrix calculations on the PIC quickly resulted in random results.

The BANKSEL optimization in SDCC absolutely doesn't work, once you get over 256 bytes of RAM. Using the __naked keyword anywhere but the simplest program doesn't work.

The return address stack is only 31 levels, which might be exhausted in a complicated math function. So the idea was to use an el cheapo PIC to make a standalone stick controller with heading detection that would allow the azimuth on a monocopter to always point nose out.

Having a standalone stick controller is a drastically different experience than a touch screen or a stick controller tethered to a computer & a test article would be valuable in comparing the experiences.

Of course, the reason for the PIC was manely because it didn't seem a big enough problem to justify any more horsepower & it seemed mass producible. In reality, it absolutely is not cost effective to mass produce a stick controller in lieu of a phone interface & it doesn't have the publicity of a phone interface.

It can minimize the aircraft weight by using chip radios, but at the very least, the aircraft weight can be minimized with a bluetooth chip...Continue Reading
Posted by Jack Crossfire | Dec 05, 2013 @ 12:58 AM | 3,987 Views

The home made USB PIC programmer has been around for around 6 years. After all those PICs & all that time waiting for its extremely slow data rate of 600 bits/sec, it finally had a debugging session with an oscilloscope that exposed the problem. A single bit error & now it's up to 166kbits/sec. It's still very slow, but bearable.

166khz is almost as fast as an agnostic bit banging protocol over USB can go. Past strategies used a bootloader to speed it up, but it needed a lot of extra resistors & tended to erase the PIC on its own.

The official Pickit programmer was once $30. Now, it's $45. Any future paid project would definitely involve buying the official programmers instead of making them from scratch.
Posted by Jack Crossfire | Nov 30, 2013 @ 09:47 PM | 4,817 Views
a high speed, FPGA driven camera for flying Marcy 1

The monocopter remanes an interesting way to fly with the least amount of material. The ground based camera isn't very practical outside of a demo, since it can only hover in a single place. The FPGA version still requires highly controlled lighting. Hovering in a lit room is still more useful than hovering in a dark room.

A manually flown monocopter with a basic 3 channel stick controller may be extremely old fashioned, but the aerodynamics have gotten to the point where it could be a very exciting toy. Don't think any tablet interface is going to provide the same experience as old fashioned joysticks, although tablets provide a different experience.

If the user wants it to fly itself, it could be a rare enough occurrence to get by with a basic webcam that only works in the dark.

a balancing robot

It would be focused on autonomous mapping, using IR sensors or sonar. Another idea is using an articulated camera system to automatically make a 3D world. Making a 3D world like street view or a map is just more easily done with a human carrying around the sensor than with a robot. So maybe the focus could be on a map making sensor itself.

A balancing robot would make more sense if there was a day job coming that involved the ATmega328. Trade shows were not a viable way to fund startups, in the old days. We used to leave Las Vegas trade shows with 200 very promising leads, but they were more interested in...Continue Reading
Posted by Jack Crossfire | Nov 30, 2013 @ 08:19 PM | 4,517 Views
Running a startup on Haskell (50 min 23 sec)

There's a guy who makes you feel small. He's done a lot more in the same time you've been alive than you ever did. His formal education only went up to a BS in CS, yet he did everything from teaching a class at Stanford to starting a company, writing a book, & managing engineers.

Some items of note were he never mentioned working on something that wasn't in a formal environment, collaborating with other people who saw what he was doing. Where the rest of us might have hacked on a problem that no-one else was, alone in our bedrooms in college, he mentioned working with a bunch of other research students in the same room, on a fairly established problem.

Then, in professional life, he mentioned working on a small project outside of his day job, but it was with someone else & it was still related to his day job. He never did anything that wasn't a collaboration.

His book was a collaboration. Instead of lazily writing a wiki like most of us would, his 1st move was to approach O'Reilly to see if they would publish it formally. It's definitely a different way of thinking to make sure everything you do is done in a formal environment or part of a job, but it's probably reality if you want to make money.

He never mentioned any hardships with anything he did. The opportunities & money just effortlessly came. He mentioned working on obscure technologies as making resumes stand out, because it showed when...Continue Reading