RADIO STATION

My friends wanted to drive trains running near them! Well ! You must do a radio control!

 

OK! I try.

 

The basic idea in in fig.1

 

Encoder+Tx  to Rx+decoder/DCC drive

 

 

 

 

Encoder

To select speed we wanted a pot, to quick select addres  thumbweels; the next project may have displays and puls..we  shall see!

 I chose the PIC 16F286, cheap,easily reprogrammable (how many time, my son).

The A/D conversion is made with the comparator.

Next version will drive two trains with the 2nd comparator builted in.

 

Now the encoder/ decoder runs with 28 speed standard, but it easy convert to select also 14 speed and 99 addresses.

I have also ,of course, the direction speed, and a switch for FL, F1 ( is enough for us), a button for emergence stop and a button for a 2nd  speed.

The 2nd speed is usefull in some situation, ex when train arrive in station, or you want switching cars; this 2nd speed is stored in the EEPROM of PIC; you may adjust it by the following procedure:

-before switch on trasmitter, select a speed with the address thumbweels... ex 01.. this is no address, but the new 2nd speed;

-         than you push the F1 button and switch on the trasmitter...wait some seconds  and switch off the tx. Now 2nd speed is in memory! Before to drive train, remember to select the rigth address!

 

For the TX and RX you may choose wath you want..I have choose  a ready to run wafer running at 433 MHz (by AUREL) ...speaking to a super reactive receiver.

This because for next step is necessary to have a TX+RX in the driving set, and also this one is in the same little card! (cheaper and easy to use than a sparate TX and RX at 866 MHz that runs better).

 

 Well ... now i have the base to drive 1 train (2 on next realise) with the base...but other friends?

Other friends with slave TX running on same frequence.

 

 

 

 

 

 

The trasmission has a Tf (time of frame) ; in this frame i may have some slots (Ts) for every trasmitter;this slots are different for TXm, TXs1, TXs2 ecc.

The project may be changed with polled (from base) Tx.. i will see next, but so we will need another TX in the base!

 

Is important that differents trasmitted slots don't overlap each other; because precision and stability of quarze don't secure this, i need syncro the trasmitter.

 

This is done by the master ( but can do it also a slave!); when it transmits the code to drive trains, also resets the timers of the slaves. If  a slave is working alone, occours a timeout and the slave runs happy!

 

Timing.

 

I must transmit: 8bits for address, 8 bits for speed and Fx and direction and 8bits for checkbyte!

Because the bandwhidt of TX-RX i had (2 KHz), this version go slow! I refresh the signal to base 4 times/sec ( Tf = 250 mS) and every slot lasts about 70 ms.

So now you may have only 3 tx running together! (i tried with 2! And is running well).

If I want more tx I may do the frame wider ( 400 mS ?), or shorting the slot time ( no checkbyte, but 1 or 2 parity bits or shorting the HI-LO bits transmitted... now Hi bit=2 mS and LO bit = 0,8 ms).. i will see in the next alpha version.. a.200034!).

 

 

 

 

 

   

             TX MASTER                                     TX SLAVE

 

 

 

 

 

 

 

 

 

 

 

 

Note: pin 14 is 16! Pin without number on + 5V is pin 14; 

 

 

RECEIVER

 

The receiver use a world famous PIC16F84 (you may change with 16F628) for decoding signal and encoding to DCC Standard.

 

Next version will have also the pot and buttons to drive a train, ex in station! For now i am hurry and want test it to see what happens without other things!

 

 

 

 

 

 

 

 

 

RECEIVER

 

 

 

RECEIVER+POWER BOOSTER

 

 

 

 

 

 

 

 

For all your needs mail to me

 

 

 

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