i want to connect two arduinos (A, B) and talk from one to the other the simple way, but it is not working.
i already searched the forum but the hints are not clear to me.
what i have so far:
i uploaded on arduino A the 'serial_read_basic' example sketch,
to arduino B the 'serial_write_basic' example sketch.
a cable from arduino B's TX to arduino A's RX pin.
a cable from arduino B's GND to arduino A's GND pin. i tried also without.
besides that its the classical pushbutton circuit. i press the button and arduino B should send data. while arduino A should recieve data and to indicate that the LED on pin 13 starts to blink.
arduino B is plugged to an external power supply
arduino A is either connected to USB or external powered with arduino B, i tried both.
First the easy one... if you run the LED blinker example on A, does the LED blink? (wondering if you have it in backwards) After we get done with the easy one...
Second, another easy one... Does the LED blink on B? (just checking that the switch is right.)
You certainly want the grounds connected. The crossing of the signals is also correct.
Perhaps the problem is that you have two things connected to the RX pin on A? The USB<->serial chip on the arduino board is connected to that pin and driving it. When you connect the transmit pin from B to it also you now have two things driving the same wire which is bad. One might "win" and force the logic to the state it wants, or they could be evenly matched and put the pin at an invalid or unstable level, or you could overload the outputs and burn one out.
This may not be the problem though, I look at the schematic and see a 1k resistor between the USB chip and the mega8, I would think your other logic signal will win safely.
everything is working. no matter if external powered or not.
maybe it was only the point that i have to connect a wire from RX to GND while switching on the external powered (well covered in the forum). now i put a visual check into setup (blinking led) to signal when to remove the wire.
next step: TX-RX communication with wireless via RF
After replacing the cable connection with the modules and adjusting the baudrate to 4800 it didn't worked. The RX LED was blinking sometimes at their own will.
A little research and reading the instructions carefully showed this picture:
the transmitter module sends the data as 'manchester coding', and the reciever has no logic to decode manchester.
From here are to ways to go:
digging deeper to realize a manchester to rs232 communication or
buy modules that speak rs232 (like easyradio modules as far as i know)