Orangutan: the missing manual?

Support A-Star and Orangutan
21

We really like the mega168, so we’ll probably have some form of robot controller based on it for as long as they are available.

We had an AVR programmer in the works (including first revision PCBs and code) way before the X2, but I think the thing that initially stalled us was consideration for multiple operating voltages and the necessary clock speeds to run at low voltages but support 115 kpbs like the AVRISP. But supporting all kinds of different AVRs wasn’t something we really wanted to do, and we couldn’t compete with Atmel’s low-cost tools. The thing that really justified a built-in programmer on the X2 was the realization that it could also serve as a co-processor when the target device was running. Once we had the code working on the X2, we made a new programmer; it’s completely different from the original unit we were working on, and it only works at 5 V and 20 MHz.

We like AVR Studio and expect to use it for our examples. For me, setting up the IDE is something I do once in a long while, so I tend to forget if there were any issues getting things running. I think the problems often revolve around support for new programmers and processors, and since we’re not changing either, I hope we’ll be set.

The LCD we’re using isn’t from Crystalfontz. I just looked at the one they have (they didn’t have that last year, I think), and it looks similar, so we’ll have a backup if our current source runs out. We don’t intend to discontinue the Orangutan, but we are thinking of a few modifications we’d like to see on future revisions. Would you mind a slightly bigger unit if it meant a bigger operating voltage range and higher-power motor drivers?

- Jan

22

Ooooh! A chance to play!

Yes, I could live with a larger form factor if it meant a wider range of operating voltages and higher powered motor drivers. But just to come clean, here’s my wish-list:

1 - I really like the ability to jumper how power is supplied to each I/O bank. I like that I was able to install a three-pin 0.100" header and just set it with a jumper. So far I haven’t dedicated any of the Orangutans I’ve got to a single purpose, so things tend to get swapped out. A “solder once 'n forget” style power jumper has less appeal to me. Please don’t change how this is done.

2 - I wouldn’t mind seeing a larger capacity regulator on-board. But the impact of this is lessened by having the jumpers mentioned in #1: I can always take a larger 7805 family regulator and jumper it in to supply power to a given bank. Still, having 250mA available would be pretty sweet, and would probably make external regulators unnecessary for me.

3 - Bigger H-bridge for the motors would be quite welcome. (I take it you’re not talking about the 14/30A drivers for the X2, right?) To give a size range I’d be interested in, take a look at the XMods line of R/C cars. Goofy, I know, but stay with me for a sec. The stock motors ran right around 1A or so. There are after-market motors that would easily draw 7A while getting up to speed. Why mention this? It’s a 130 frame motor, and lots of people supply them now. The larger series GM motors from Solarbotics all take 130 frame motors. So you could potentially start with, say, a GM2, swap out the 9kRPM motor with a 45kRPM motor, and get five times the speed at considerably more torque (and consequently more power draw.) If you can stick 10A FETs on the Orangutan, I’d be plenty happy.

4 - Bring all the I2C, SPI, UART, etc. lines out to headers without losing any of the ADC lines. (I think I’m pushing my luck here…) Never know what someone’s gonna plug into the thing. (At the very least, leave the current I/O header alone. But I wouldn’t mind getting the SPI lines without going through the ISP header.)

Past that any changes I’d make are things I’d have to do (like wiring up the battery through a divider to one of the ADCs so I can get battery level - I like that the X2 has this as a jumperable option.)

The shorter answer? Yeah, I’d deal with a larger form factor if it meant I could drive bigger motors.

Tom

23

To make sure I understand: you don’t like the Orangutan X2-style solder jumpers because you forget it’s an option to change their state?

- Jan

24

Heh! Boy I really was in a bad mental state when I typed that… My apologies for being unclear.

No, I don’t dislike the X2’s jumpers. But I like the Orangutan’s better.

Worst case would be to not have jumpers at all since that ties the developer in to a particular power source (NOT what I would want.) Best, for me at any rate, is a jumper that allows you to solder in a connector of some sort. This makes supplying off-board power dead-easy, and makes adding jumpers that can be changed with fingers a lot easier.

Here’s a f’rinstance:

A while back I was building a rig to carry an R/C controlled camera aloft using a kite. Three servos in the system, one modified for continuous rotation. Unfortunately my transmitter battery was dead, so I couldn’t center the servos using the radio. I pulled out my Orangutan, spent about five minutes writing some code to output 1.5ms servo pulses on four of the channels, loaded code, and swapped the jumper for that bank from Vcc to Vbatt using my fingernails.

Centering the servos took about two minutes past that. I finished up the KAP rig, and when the new transmitter battery arrived, everything worked great.

This is one of the things I like about the Orangutan: it’s soooo easy to use it not as a dedicated processor, but as a general tool to keep in the toolbox. Granted, I’m less likely to use the X2 this way simply because it’s massive overkill for this sort of thing. But if the Orangutan’s power jumpers were changed to be X2-style jumpers, I think it would take away some of the utility of the device. I like that part of the Orangutan the way it is.

Sorry for the confusion.

Tom

25

Rekindling a cold topic…

I generally like the Pololu manual style, but I’ve always had an odd problem with their PDF’s. If I’m looking for a particular term I know is in the document, and I try to search for a word, something like “reset”, it is never found. Out of curiosity I tried to copy some text out of a few of the manuals, but whenever I paste it into another program, say notepad, I just see the “I can’t display this character” blocks.

The really funny part is if I copy and paste the word into the Acrobat search bar it will find all instances of it. Are the Pololu manuals written in some crazy, non ASCII compliant font? Am I the only one who has this problem?

-Adam

26

I didn’t know about that. Our manuals are made in Corel Draw, which has its own PDF generator that we usually use. The text copying works in the new Orangutan X2 quickstart guide, for which I think we used Acrobat directly, so we’ll use that in the future.

- Jan

27

Yay, another reason to add to my list of why I don’t like Corel Draw. It seems to have used Unicode rather than ASCII in the older manuals, but the character codes don’t correspond to any Unicode standard I can find. I’m really confused as to how Acrobat manages to display it at all!

-Adam