P2 controlling 27 MHz radio controlled F150 toy truck
Tubular
Posts: 4,702
Spent an hour yesterday arvo proving the P2 could transmit commands to a $20 toy RC truck, using nothing more than a 14.6" bit of wire attached to P0
This truck uses a 27.145 MHz xtal osc, modulated with 2500 Hz on-off keying of that osc. Command was 60 bits long before repeating
Early days yet, at the moment only one command implemented in a long unrolled loop, but eventually will get all the commands and combinations implemented. It was just fun to see it work, and a pleasant break from PLL wobbles. Longer term, we should be able to get P2 to 'record' RF commands, like universal remotes do with IR, to make it work with anything 27MHz
This truck uses a 27.145 MHz xtal osc, modulated with 2500 Hz on-off keying of that osc. Command was 60 bits long before repeating
Early days yet, at the moment only one command implemented in a long unrolled loop, but eventually will get all the commands and combinations implemented. It was just fun to see it work, and a pleasant break from PLL wobbles. Longer term, we should be able to get P2 to 'record' RF commands, like universal remotes do with IR, to make it work with anything 27MHz
800 x 480 - 53K
4608 x 3456 - 3M
3456 x 4608 - 2M
4608 x 3456 - 2M
4608 x 3456 - 3M
Comments
How did you generate 27.145MHz, and how close did you get ?
Looks like 20M/2 then *19, and a /7 can get to within 79ppm, which is likely good enough ?
So 20 / 7 * 38 / 1 = 108 MHz, /4 (inside rep loop) generates 27.143 MHz
Everything happens in 400 uSec blocks, so the on off keying code looks like this for a burst on then off
I was thinking of a smart pin PWM /7, but there is something seriously cool about SW bit-banging a 27.143 MHz carrier !!
Shows the power of the REP opcode
Other micros might do bluetooth, wifi, but we can bitbang 27MHz
Reminds me that we really must have a go at 13.56 MHz RFID
Great work, I just may have to buy a toy to try it LOL
That would be real handy
For sure, it will keep us all busy for quite a few years. there's still tons to be explored in Pop1
http://bscircuitdesigns.com/Misc/SPIN CODE EXAMPLES.pdf
Before I dived in, I found a site that mentioned about the commands being simple a number of cycles in between two headers. The protocol for this truck was slightly different, some of the On and Off delays are double-width (800 uSec duration). But I went through the same procedure as you with the scope
Beau,
I have an old /cheap rc car (no RC-steering just fwd / rvs).
It's only marking is "08AT1"
I punched in your demo code from the pdf and amazingly the car did respond !
However it only goes in reverse for any of the commands(reverse,forward,etc).
I even tried varying the signal from 0 to 1000.
The only thing that happens is the motor just stays on longer for higher values of 'signal'.
I don't have the transmitter handy , and even if I did,the only 'scope' I have
is the *spinscope*
I tracked down the id of the receiver from the FCC #
It is an :
Artin Industrial R/C Toy Receiver 43910R FCC ID L9G43910R
Frequency Range
49.82-49.9 MHz
...and indeed it does respond to the propeller from ~49 700 000 to ~50 000 000 !
Do you have a guess on what is needed to make the car go forward?
Mike
Maybe this car only goes forward .....and I got a defective one with the motor wired / connected backwards
Still trying to track down info on it.
There's a ton of info on "bitcharger conversion" type cars on rcgroups
Did you mean could a second P2 read a signal from a transmitting P2? Not at this stage