My question is, would it be possible to power the board by sending 5V into one of the pins in the “EXT 1” or “EXT 2” that normally outputs 5 volts? For those of you who aren’t familiar with the development board, “EXT 1” and “EXT 2” are headers on the board that bring out the pins from the chip so you can easily connect devices to them.
I’m pretty sure this would work, but I wanted to ask before I smoked my board
I was messing with some XBees connected to the AVR MT 128. Made a little cable from the AVR to a regulated breakout board for XBee called an AppBee (I’m getting my raw breakout from SparkFun Monday), and I was powering the module off the +5 from the serial connector (not the DB, but the molex).
I could get it to work a few times, transmitting from the AVR, but then the AVR MT 128 would just hang. At the hang the +5v from the AVR to the XBee breakout would go to +4 and the AVR display would go blank - the system was dead.
I powered the XBee from a bench supply (shared ground) and it worked just fine. So, tried running the XBee’s vss from the AVR MT 128 EXT2 (pin 1 and 2) header and the same problem happened.
So, I took your hint above and powered up the AVR with a +5 from the [SFE DC-to-DC step up (2 AA’s) through the EXT2 header. After that I had no problems powering the XBee module through the +5 coming out the RS-232 molex.
So, just wanted to say thanks for trying this first and sharing the info. I used it and it worked well.
For some reason the regulated 5v generated if it’s powered by 12VDC jack, can’t push much.
The pic above shows the XBee being powered by the 5v from the RS232 molex and the system being powered from 12VDC wall wart. This configuration didn’t work - it would transmit a few times and then the AVR would belly up.
The image above shows a USB/XBee dongle on my PowerBook. Using this command:
screen /dev/tty.SLAB_USBtoUART 9600
I could pump keystrokes at it and they’d display on the AVR MT 128 LCD.
That command works fine on my SuSE linux machine (albeit a different USB device), to talk through an XBee also. BTW - to get out of the screen command and drop the port, Ctrl-a :quit.
I think SF is selling the incorrect Wall Adapters for the AVR MT 128. I bought a couple about a year ago and they work fine, then I bought some more (AVR MT 128 & Wall Adapters) and the wall adapters don’t work at all on the new AVR MT 128 boards. The AVR MT 128 won’t even power up!
The new AVR MT 128 boards also have gray buttons instead of black ones. So, maybe Olimex changed something on the actual AVR MT 128 that makes the Wall Adapter not powerful enough?
I don’t need the Wall Adapters anyways, so it wasn’t much of an issue…just a little annoying when I was first trying to test the board.
In my case, I wasn’t using a wall adpater from SFE - I just cobbed a 12VDC wall wart from an unused NetGear router, so it should have had plenty to spare. It seems like internally, the 5v regulation is limiting current.
BTW - definitely not recommending anyone try the DC-to-DC battery gig - this combo of AVR and XBee will eat it for snacks. But it does work as an injection test
I don’t understand why Maxstream doesn’t get it. They just blew me off.
So, I searched high and low for this type of product. I was tickled to see the SFE breakout recently offered. It’s a toe in the water and I hope to see a lot more.
But, before that alternative existed, and with no help from Maxstream, I finally found AppBee - http://www.selmaware.com/appbee/
Most of these are designed to fit various Parallax products/boards/Propeller, but they aren’t limited to that obviously. The thing about AppBee is it’s the only one out there I’ve found (I found some designs and “geekything” on the forum has a design…should be receiving a prototype of it one of these days). AppBee boards are expensive for what you get, but it’s the only game at the moment. My hope is SFE will develop a family of these types of boards - the types and useful variations are endless. Hopefully, the SFE breakout is just the beginning.
So, I’ll just say I’ve had good luck and service from the AppBee boards, but hope SFE will kick it up with some cool new stuff, too. They have every appearance they will be and that makes me happy…I think a lot of people would be interested in XBee related boards and products.
Maxstream, now owned by Digi, no doubt makes these modules to be designed-into OEM products. So the lack of 0.1 in spacing connector isn’t an issue. The hobbyists always come up with low volume gizmos to adapt these things. It is good that Maxstream’s pricing is as good as it is, compared to most of the other 802.15.4 module sellers.
The Lantronix WiPort also has an odd connector pin spacing, by US conventions. Even more odd is the kind of connectors used on the 802.15.4/ZigBee modules from Silicon Labs/Helicomm, Jennic and others - the ones that are plated PC board-edge indentations.
I just purchased the AVR-MT-128 from Sparkfun/Olimex. However, how do I power it? I have a 9V wall wart (radioshack “M” adaptaplug) plugged into it however nothing shows up on the lcd.
Also how to program it? I have JTAG ICE but avrdude always says no response.
I’ve purchased 7 or 8 of these things and I found that the newer ones don’t work on 9V. You need around 12V. Although, if you bypass the built in regulator you can use 5V (see my first two posts on this thread).
I’ve never used the JTAG. Try programming it again while providing 12V.
I see. It looks like a 7805 is used as the regulator so I can’t see why it wouldn’t work off of 9volts. The dallas touchbutton & relay stuff uses 12 volts but I have no use for those. I will try your suggestion of directly feeding in 5volts.
ps: How will I know that the avr is in fact running when I power it if I do not manually program it. I’m guessing something will come up on the lcd or the led will light or something. What is the atmega128 programmed to do once shipped from Olimex/Sparkfun?
Thank you for your replies, I appreciate your responses. I purchased this expecting a README file and was hit with only this device in the box. So with my limited electronics skills it’s been a hassle because I’m more of a programmer.
I have taken a look at the sample code provided on the Olimex.com site but that’s all it is for now…code; I can’t even power/program the samples yet.
Well today I actually went through my pile of AC adapters and couldn’t believe that I already had 3 adapters that were 12volt and had the right tip size - and I had wasted 3 days just trying to get the right adaptaplug tip from RadioShack. So with one of those adapters the board functioned and programming/debugging worked under Windows in AVR Studio. avrdude is a different story.
Edit: seems I just have to unplug/replug in the programmer and everything works fine after that. I am now set to do some programming!
and sharing the info. I used it and it worked well.
