RF w/434 mhz sparfun pair and LCD
- Thread starter alistairsam
- Start date
That would be roughly right. You can cut costs by almost half if buying NKM2401 chips to fit directly on to boards and not using the AXE213 boards. You can save costs by buying cheaper RF modules.
Most people probably wouldn't want to set up transceivers ( so that cuts costs in half ) and for one-off projects and ease of use the AXE213 plus the RFA001 modules saves the cost of constructing the circuit or PCB and trouble-shooting RF modules. The AXE213 boards both connect direct to PC's via standard download cables so can be used to check the links work without a PICAXE. On top of all that the AXE213 receiver board can connect direct to an AXE033 for a wireless LCD display.
So a fair number of options to choose from and, as always, you can go for ease of use and 'tried and tested' or can cut costs at the expense of increased effort elsewhere.
alistairsam
Senior Member
TDM - Time division MultiplexingWhat's "TDM"?
It sounds very impressive and knowledgable
Or is it short for "tedium" ?
http://en.wikipedia.org/wiki/Time-division_multiplexing
my guess was that he'd use the transmitter and receiver alternately using timeslots and not at the same time, that way the receiver wont be swamped by the transmitter next to it. again, just guessing, but TDM is a common technique for multiplexing two signals.
alistairsam
Senior Member
I could save cost by using the Nordic 5 Key Fob's and a nRF24L01+ receiver. only need to find out if it can be interfaced to the picaxes. as it works in the 2.4Ghz range, I could then use an ASK transceiver in the 315Mhz range for the LCD data and unit A. or even a 933Mhz transceiver as its "quieter" in that band.
a search in this forum showed two threads with "nRF24L01+", anyone had any success with this and picaxes? just getting serial data?
http://www.littlebirdelectronics.com/products/Nordic-FOB.html
http://www.littlebirdelectronics.com/products/Transceiver-nRF24L01%2b-Module-with-Chip-Antenna.html
a search in this forum showed two threads with "nRF24L01+", anyone had any success with this and picaxes? just getting serial data?
http://www.littlebirdelectronics.com/products/Nordic-FOB.html
http://www.littlebirdelectronics.com/products/Transceiver-nRF24L01%2b-Module-with-Chip-Antenna.html
How about three parallel-connected receivers,
facing different directions?
See post #9 and #10 here:
http://www.picaxeforum.co.uk/showthread.php?t=8227&highlight=receiver*
e
alistairsam: Just what type and how big is this 'scope? Have you actually done any IR experiments? Vishay detected IR is usually able to be read well even when bouncing off the most trivial reflectors - hands,clothing,walls,windows etc, and output can be easily boosted by overdriving the IR LEDs briefly too. All manner of clever IR-PICAXE applications have arisen, with ranges of many metres (even in sunlight) the norm.
Although better 433 MHz modules can have their power wound down to µW level, my RF experiences show you will get overload with even just a few milliWatts at such short range, especially if similar units are operating very nearby. HopeRF units (of ~3mW output) will not usually work unless at least across the room from each other. Stan. (who prefers to control telescops from PCs)
Although better 433 MHz modules can have their power wound down to µW level, my RF experiences show you will get overload with even just a few milliWatts at such short range, especially if similar units are operating very nearby. HopeRF units (of ~3mW output) will not usually work unless at least across the room from each other. Stan. (who prefers to control telescops from PCs)
Attachments
Last edited:
alistairsam
Senior Member
Hi Stan,
I have done some IR tests, and I guess it could work for the button control of the focusser motor and the RA drive motors.
but as the handheld remote has the LCD as well, it needs uninterrupted data from the encoder unit. so I'd have to go with RF for that, and I'll check specs on the xBee's to see if that'll work for low power short range links.
My scope is an 8" F6 Newtonian (120cm tube) on a home built fork mount, so the focuser can get into odd positions, but should still work with IR.
I'll try the 3 IR Detector trick as well and if I place it below the optical tube, it would cover most positions when I want the motors to rotate.
is it possible to use one IR transmitter (or a pair) to control two different IR receiver units based on which buttons are pressed? will do a search on this forum.
I think this approach would be the simplest and most reliable as I'd have only one RF link for the LCD data.
you mentioned some modules will need to be atleast a room away, is that even without antennae at the receiver and transmitter?
Although PC control of scopes does most of whats needed, I designed this mount from ground up to be autonomous, so I'll be replacing the LCD with a graphics LCD at the end so I can view pictures of objects on the handheld remote. it will eventually be a goto system where I choose the object from a list and it sends commands to the picaxes to drive the steppers. bit more to go for that though.
Yes. Each PICAXE will receive the same IR Commands, each simply has to ignore those commands it is not interested in.
If you build a remote containing a PICAXE you can use INFRAOUT or IROUT and send up to 128 commands. You can specify IR data sent as 'destination' commands (bit6=1) and 'data payload' (bit6=0) so can have a number of commands for each receiver.
Last edited:
alistairsam
Senior Member
Hi
would anyone have a schematic for an IR transmitter that uses sony codes using the picaxe and is as powerful as normal universal remotes?
I tried using a universal remote and was thinking of opening it up and connecting only as many buttons as I needed ( I need only 7), but problem is it keeps losing the programming code.
so if I have a static setup with the picaxe already programmed for sony codes, it would be more reliable.
I had a read of how to increase current to the LED using PWM, but needed a "safe" circuit so the LED won't blow up if pulsed for too long
(my button press would be for a few seconds to a minute or more).
Just what sort of so called universal remote ARE you using? A steam powered one?! As it's 2010 setups stashed away in NVRAM should stay there! I've a US$3 univ. remote here in NZ that still holds it's setup codes months later- perhaps you should try another coin shop offering?!
Last edited:
alistairsam
Senior Member
i'll try another one, but I got this in 2008. (not 1888) and worked for 4 devices. but hadnt used it too much.
is there a DIY transmitter similar to the one in the IR kit axe040?
You can always use a numeric keypad, 08M & IR LED to rustle up your own. See the diverse approaches Andrew has here =>http://picasaweb.google.com/picaxe/Data#
However the bill of materials will probably exceed the cost of IR remotes now thick on the ground at coin shops etc.
However the bill of materials will probably exceed the cost of IR remotes now thick on the ground at coin shops etc.
alistairsam
Senior Member
thanks. else are there chips that are built for these transmitters that can be used without a picaxe.
i'm just trying to maintain a small form factor for my handheld remote and it'd be tough to do it if I used the pcb from a universal remote. thats why i was looking for picaxe based or discrete chip. will look at andrews projects.