Yes, I just used the standard configuration in the datasheet. The aerial depends on the frequency and your application. I have very little experience with radio transmission, so I can't give you very detailed answers. I would say that the signal generated by the Prop is not very clean, and you would be better off using an external RF module.
Thanks, just to clarify with a wire as aerial coming from pin 1 should I use a capacitor & resistor before ground or literally just plug the next hole on my breadboard to ground?
purplemonkey, which program are you running? The AM program transmits at 1.42 MHz and the FM program transmits at 92.5 MHz. The signal is so noisy that you should be able to pick it up on lots of different frequencies on either the AM or FM band.
Hmmm fm one but it seems to go shhhhhh-break-shhhhh 5 times getting progressively quieter then turns off. I can't figure out why it's not working properly I've programmed EEPROM fine but it has to be directly on top of the radio to receive anything I think it's not working properly. If I disconnect the battery and the reconnect it does the shhhh-break thing again five times and then turns off. Bizarre I've checked and double checked connections and they all seem correct. The only thing I can think off is it maybe the capacitors for the voltage regulator that are going directly into the bus are the problem I don't know. Pulling my hair out what I really need is a picture of how it should be connected up on a breadboard. Don't know if anyone is kind enough to oblige????
The Prop manual has a diagram of the basic wiring setup for the Prop. Can you run another program on your Prop, such as something that prints out a line over and over? Maybe the voltage on your battery is low. When a battery gets low you can usually still load a program on the Prop, but it will stop running when it starts up more cogs and uses more current.
I wonder if the transistor - cheap prop plug substitute on the board is zapping current??? Going to unplug it and see as battery is new and still knocking out nine volts to the regulator which is knocking out 3.3v. So with the fm spin file I'm ok with a 5mhz crystal oscillator and there's no need to modify spin code? It's just I noticed someone was using 6 MHz oscillator???
Also when I unplug rx and tx and reset it should still work right? Obviously I won't be able to program it but it should still work right?
Trying to program EEPROM now keep getting write failed on com 3. It works fine with all other files just the fm transmitter file I think the wav file is making it timeout or something. Any ideas anyone?
purplemonkey, it seems like your hardware configuration is (how can I put this gently?) not meeting spec. Can you post a schematic of what you've implemented? I would suspect your implementation of the transistor circuit that replaces the Prop plug. I suggest that you invest $15 in a Prop plug.
ok here is the breadboard layout, made a mistake on layout and aerial is in pin0 rather than pin 16 but its still going to gound the same way. The problem seems something is draining power when initially turning on it works albeit quite a weak signal (radio has to be right underneath it) and then transmits 5 or 6 times with decreasing strength and then turns off. Any ideas would appreciated? incidentally i'm using the cheap prop plug replacement hence the middle part of the circuit with the transistor.
ok here is the breadboard layout, made a mistake on layout and aerial is in pin0 rather than pin 16 but its still going to gound the same way. The problem seems something is draining power when initially turning on it works albeit quite a weak signal (radio has to be right underneath it) and then transmits 5 or 6 times with decreasing strength and then turns off. Any ideas would appreciated? incidentally i'm using the cheap prop plug replacement hence the middle part of the circuit with the transistor.
One obvious problem, you have P0 shorted to ground. That's going to prevent anything getting to the antenna.
Well the obvious thing is that your shorting an output pin to ground. Don't do that. Take the ground wire off, and if you haven't destroyed the pin try it again. If you have destroyed the pin, then move the output to another pin and try it. There's a constant defined in the program that determines which pin is used for output.
You may want to add a bypass cap between the ground and power pins near the Prop. The Prop's power may be a bit glitchy right now.
Other than that it should work OK. I would suggest running a program that flashes an LED or uses the serial interface to check out your hardware.
I'm not sure where you got that idea, but no, the aerial does not have to go to ground. And in general, you should never connect an output pin directly to ground or power.
You need caps on both sets of power pins on the propeller. One between + and ground pins for each side of the chip. Also one for the eeprom power pins. The standard bypass cap of .1uf *ceramic* will do just fine.
Sorry I'm using a spin file called 2m_fm_modulation1 it's the one that has the wav file called expectu.wav with it, I think it maybe the one that uses the video function to send audio signal
Sorry I'm using a spin file called 2m_fm_modulation1 it's the one that has the wav file called expectu.wav with it, I think it maybe the one that uses the video function to send audio signal
Could you supply a DIRECT link to it. There are thousands of files here. 2m_fm_modulation1.spin does not show up on a Google search
This thread was started by Dave Hein based on the AM and FM transmitters attached to post #10 of this thread.
I've experimented with the FM version.
It puts out plenty of power for expermetation, it worked really well with no antenna on my workbench. With a random 1 foot wire attached to pin 16 it worked too well, I picked it up on my car radio 1/4 mile away.
As for connection to ground, it would be a good idea to do that through a say 100 ohm to 1k resistor (i.e. dummy load) as this and all other Propeller-based FM transmitters put out really dirty signals.
Also just tried the one on this thread changed pin to 17, but still same problem there's no tone just a ssshhhh-break-ssshhh sound for four or five times then just dies on 92.5mhz
Comments
Also when I unplug rx and tx and reset it should still work right? Obviously I won't be able to program it but it should still work right?
ok here is the breadboard layout, made a mistake on layout and aerial is in pin0 rather than pin 16 but its still going to gound the same way. The problem seems something is draining power when initially turning on it works albeit quite a weak signal (radio has to be right underneath it) and then transmits 5 or 6 times with decreasing strength and then turns off. Any ideas would appreciated? incidentally i'm using the cheap prop plug replacement hence the middle part of the circuit with the transistor.
One obvious problem, you have P0 shorted to ground. That's going to prevent anything getting to the antenna.
http://www.youtube.com/watch?v=q_Q5s9AhCR0 Watch at about 2:45
Also, some breadboards break the power rails in the middle. Do you have a bridge for that?
You may want to add a bypass cap between the ground and power pins near the Prop. The Prop's power may be a bit glitchy right now.
Other than that it should work OK. I would suggest running a program that flashes an LED or uses the serial interface to check out your hardware.
Also where should I put a cap? Bit confused? Between ground and power on the prop chip?
In FMTransmitter2.spin, I think txpin=16 is pretty apparent. (That's P16, physical pin 21 on 40 Pin DIP).
So.. you tried to run the code just changing the physical output to P0 without changing the code? There might be hope for that pin after all!
Could you supply a DIRECT link to it. There are thousands of files here. 2m_fm_modulation1.spin does not show up on a Google search
This thread was started by Dave Hein based on the AM and FM transmitters attached to post #10 of this thread.
I've experimented with the FM version.
It puts out plenty of power for expermetation, it worked really well with no antenna on my workbench. With a random 1 foot wire attached to pin 16 it worked too well, I picked it up on my car radio 1/4 mile away.
As for connection to ground, it would be a good idea to do that through a say 100 ohm to 1k resistor (i.e. dummy load) as this and all other Propeller-based FM transmitters put out really dirty signals.