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7:56 pm
June 4, 2008
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robotman
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Okay, radio433.png and radio433.txt are in the FILES section ready for viewing and/or download. Sorry about the PNG picture file being so wide and tall, but I can't seem to get Eagle to scale it down any smaller. At least the filesize is small though.
The TXT file just shows a bunch of PIC16 configuration settings that I used for my simple tests of radio transmission and receiving. I'm not intending to make a tutorial out of this – I think the projects are simple enough that the info I have provided, and some judicious background material reading (ie. some self-study!), will be all you need.
The circuit I have provided can be split in two, one a transmitter and the other a receiver so that the complicated power-cycling between Tx and Rx is gone: Just tie the +ve for each respective module directly to the Vdd (+ve) of each PIC. You can hang an LED off one pin of the receiver PIC, add a push button as an input into the transmitter PIC, and write the software so that the LED is turned on and off via a [remote] press of the push button. Make sure your two circuit boards (or breadboards) are separated by at least 30 cm, preferable more, to avoid the transmitter overwhelming the receiver's input – this happened to me the first many times and I was chasing shadows trying to fix something that wasn't broken…
If you've never done radio before then you will certainly get that spine tingling feeling the first time you press the button and the LED lights up from across the room!
Have fun!
Rod
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10:24 pm
June 4, 2008
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Gillerire
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| Member | posts 16 |
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I'm not able to see the files? I have clicked on 'Files' under my name on the left side of the screen but there does not seem to be anything there?
Is there something I'm doing wrong?
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6:32 am
June 5, 2008
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ash
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Nah, when in doubt, it is always the administrators fault. Although in this case I blame Drupal. 
I'll have a look at the perms and let you know when it's fixed!
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6:49 am
June 5, 2008
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ash
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Hmm – the threaded commenting is really annoying isn't it? I was actually trying to respond to the comment at the bottom before!
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6:17 pm
June 5, 2008
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Gillerire
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Haha, I feel your pain
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6:22 pm
June 5, 2008
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Gillerire
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Continuing my chatter from the other thread about using AVR micros and setting up a UART, I just found this:
http://www.societyofrobots.com/microcontroller_uart_50_robot.shtml
Hopefully it is a decent tutorial and easy to follow.
Rest of the site is probably worth a look too.
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9:02 pm
June 5, 2008
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robotman
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Hmmm. The files are gone. Oh well.
(I'm resigned to this sort of thing everywhere happening now-a-days. Life was better in analog, let me tell you. It might have been a little grainy or had a little hiss, but a least the message got through – always. The thing with digital is it's either all or nothing or just plain messed up which … irritating … watch … hear when … blippitybloop … squiggly … and that really squigglysquawks me.)
Yes, it *is* the administrator's fault! (Looking at Ash.) So it seems not just Kym is having trouble here…
Regards the circuit I had posted, it probably would have been a bit difficult to implement my idea because of the way the PIC drives its pins when using the built-in UART. The best thing to do would be put a transistor into the Tx path that is turned on/off at the same time as the Tx Module's power is turned on/off.
Cheers
Rod
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9:42 pm
June 5, 2008
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robotman
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No, wait!
The files are back again, but only accessible by me when I log in.
Now that's super useful. NOT.
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8:35 pm
June 8, 2008
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ash
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File permissions are fixed!
(And by fixed I mean everyone can download anything whether they are logged in or not)
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1:16 am
June 9, 2008
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Gillerire
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Nice work Ash. All working now.
Schematics looks good Rod. I have been reading up on UARTs for the AVR and think I have a handle on it. Will give it a go next weekend.
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6:49 pm
June 9, 2008
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robotman
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Thanks Ash!
I have an updated radio433.png that has a few changes so it should work now. I haven't tested the circuit actually, but I'm confident enough that if someone did build it and programmed the PIC then it would work fine.
I've never used any AVR chips myself, although I do have some AT90S8535's lying around (these are the big ol' 40 pin jobbies superseded by the ATMEGA8535) and I do have a programmer too, but never used it either. I got stuck into the PICs and the NXP LPC21's along with a side-branch into Cypress's CY8C devices and besides, Atmel never supplied any of the samples requests I asked for, so they can go jump! On the otherhand, Microchip and Cypress have been great!
By the way Gillerire, do you live in or near the Sydney metro area? I'm out West in the Blacktown area. There must be some others on this site who live in the Sydney region. It would be conducive to the physical construction of robots (of any sort) to have physical contact. Maybe somebody has the tools I don't have, and vice-versa. This goes out to all you guys and gals, by the way.
Cheers for now
Rod
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5:30 pm
June 10, 2008
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Gillerire
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I live in Adelaide sorry Rod. Though, who knows where I'll be next year.
New schematic looks good. Why can't you have both the Tx and Rx on at the same time? Is this a power supply issue of something else? Is the 4800 max baud rate a limit of the jaycar modules or the PIC?
I'm enjoying reading about the UART stuff. Love the idea that you can have a single wire that is either ON or OFF and yet still transfer so much information really fast.
Hopefully get it working on the weekend. Although I don't have a scope so I'm not sure how I'm going to trouble shoot any problems I encounter…
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2:41 am
June 11, 2008
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ash
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Melbourne here, unfortunately. Also I have no tools apart from the small ones that fit in my apartment.
On that note, if anyone in Melb has a drill press, lathe, workbench, router, high powered 4-dimensional CNC laser cutter or motorised plasma cannon please let me know…
Have you seen those TechShops they have in San Francisco? Great idea there.
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10:41 pm
June 11, 2008
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robotman
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You don't ask for much do you Ash?! Just keep thinking big is what I say…
The trouble with Australia is that everything is too far apart. And that makes it hard to get a sense of community.
What about you Kym? Where are you based? I've read all your posts about the Bioloid programming you were doing. It was really good stuff. Have you stopped, or are you just working on something else at the moment? I do programming for a living, so making the electronics is a hobby. And to have access to someone who can build bodies would be fantastic. Is there anybody here who can do that?
—
Gillerire, the reason that you don't want to be transmitting and receiving at the same time is that you want to be talking/listening to devices off-board. That is, remote devices. You don't want to be receiving your own transmissions. Sure, you can do it, but why? And most likely the receiver will be too close to the transmitter and its input stage will be swamped and overloaded – no damage usually, but definitely confused output from the receiver. And you have to stop the transmitter to listen (receive) – imagine talking non-stop and trying to hear somebody from across the way at the same time.
The 4800 baud is a limit of the Jaycar modules. I couldn't get them to operate reliably at 9600 baud. You could try non-standard baud rates up to 9600 (and maybe some modules will work okay at these higher speeds – possibly try the ones from Altronics or Oatley), but using non-standard baud rates will add unnecessary difficulty while you are learning.
You shouldn't need a 'scope, although that makes life more exciting. What about buying a Dick Smith 10 MHz jobbie? I think they're still under AUD $100. You won't be able to see the carrier, but then you don't want to. Just accept that it is there and concentrate on the serial UART data you are sending / receiving. (I know the unit is small, but the bigger ones take up *much more* of your precious workbench space, and the LCD ones cost a fortune…) You have your LED-only version working so just plug the AVR's UART Tx output straight into your transmitter in place of the 555 timer, and another AVR chip on a remote breadboard getting its UART Rx input from the receiver (and move the LED to an output pin on your receiver AVR). Flash the LED whenever you receive a byte, such as 0×55 (ascii 'U') for example, that has been sent by your transmitter AVR. (If you're new to programming controllers as well then maybe you should start with something a little easier, like flashing the LED on/off then progressing to radio comms. Search for 'blinkey led' or somesuch to get yourself started.)
Until next time!
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9:04 pm
June 12, 2008
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kym
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I'm in Melberg, too.
I get easily sidetracked. The "robot operating system" is still going ahead.
I've done as much on bioloids as I think I can. But I do hook up AX12's to a usb-based board I got from HUV, and twiddle things using phidget sensors.
The animator is still in hibernation after I lost track of time about 1 m ago, when YouTube kept going off the air.
I'm presently levering a Linux onto a couple of very small avr32 systems. Just getting the gnu gcc to generate slightly optimised code without core-dumping is a problem. Optimisation (-O2 or -Os) will be needed for on-board vision processing — the devices are sub 200 MHz but run at ~= 1/4 W.
This is part of the "big bot" multi-processor & all-dancing brainbot project I mentioned on the blog (but also haven't managed to get around to photographing or writing about yet).
Unfortunately, from the email today, there are another couple of paying jobs coming up that may take me away from robotics again.
But I have to eat, too.
At least… until the modding is done.
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2:23 am
June 13, 2008
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ash
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Ah good, so I'm not the only person that is easily sidetracked…
What avr platforms are you using Kym? I was looking at the gumstix site ealier. They are not AVR based but look like they could be a fairly good linux solution for pretty cheap.
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10:17 pm
June 13, 2008
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kymhorsell
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I had a look at the gumstix stuff. But some are based on avr's. See http://www.gumstix.com/store/catalog/product_info.php?cPath=31&products_id=139 .
These days there seems to be a lot more to choose from than just the "Robostix". Seems that platform isn't even intended to be stand-alone anymore.
The avr32's are (a) from Atmel (their NGW100), and (b) in-circuit.de's "grasshopper". They come in at around 100 aud a board, so aren't *really* cheap by hobby standards, and they don't immediately have pwm or other robot-type stuff coming out on any installed headers.
But they have linux and you can plug in a wifi module or usb host (I've gone both ways).
I have a slew of avr8 things from pololo and elsewhere, but the less said about those, the better.
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