Help with TX RX Temp Unit Please

[acestu]

Hi Enamul,

I have transistors now and the 12F675 ,however my pickit3 is not compatible with this chip and it gives me errors on the HPdev board so I am going to stick with the 16F628A, also could you tell me what the 2 unmarked resistors are please at the bottom of the diagram one on the transmitter and one on the receiver...

thanks
Acestu

[Enamul]

Those are pull-down so 10K is fine.

[acestu]

Hi Enamul,

I have just put the circuit in the drawing together but when I power up both boards nothing happens, I take it that the LED is supposed to flash ?

thanks
Acestu

[Enamul]

Which LED you are supposed to flash? Did you make the circuit exactly appeared in the schematic..if so I need to change the code. Please let me know.

[acestu]

Hi Enamul,

On the transmitter circuit I have programmed a 16f628 with your code on the HPDev board and when I have finished the LED A1 on the board flashes as per my video, but when I put it on a bread board and connect an LED to pin A1 it does not light so I don't know what is going on really....

thanks
Acestu

[Enamul]

Please post the 16f628 code so that I can check and tell if anything went wrong there.

[acestu]

Hi Enamul,

here is the code that I have used:

12f675_tx_ (3).fcf

(12.5 KiB) Downloaded 314 times

thanks
Acestu

[Enamul]

Hi
Here is the corrected code..

[acestu]

Hi Enamul,

Thanks for changing the code, what had I done wrong for future reference ?

thanks
Acestu

[Enamul]

Actually the code I have posted earlier don't designed for transistor based control of TX and the TX data out was in RA1 pin. But you have used according to schematic RA0 as data out pin which doesn't matches with program. I have added transistor control in the code and also corrected pin for data out. In config, LVP was enabled which should not be enabled.

[acestu]

Hi Enamul,

I have just tried reprogramming the chip and it says invalid device, I think because I had lvp enabled it has rendered the chip useless,

I found this article about LVP:

http://www.microchip.com/forums/m640643.aspx

thanks
Acestu

[acestu]

Hi Enamul,

I found a pic16f870 so I programmed it first time and put it together on a breadboard and it worked first time.....

pic16f870.JPG (189.17 KiB) Viewed 12745 times

16f870_Tx (1).fcf

(8.5 KiB) Downloaded 248 times

thanks
Stuart

[acestu]

Hi Enamul,

I just need to know what to connect A0 & A1 to now because I am a bit confused after you said that you have changed the code and the diagram is wrong....

thanks
Acestu

[Enamul]

My last code is according to diagram..earlier it wasn't according to diagram. Now you can just follow the diagram.

[acestu]

Hi Enamul,

I have wired up as per diagram, but I cannot get the led on the receiver circuit to flash, I am trying to troubleshoot and test each bit of the circuit, the transistor seems to be switching the transmitter power on ok, if I put an led on the data line it is constantly on, is that how it should be ?

I have taken a video of what I have so far:

http://www.youtube.com/watch?v=vCqe7fIaaZc


thanks
Acestu

[Enamul]

Hi
Are you using RX as PIC16f877a?

[acestu]

Hi Enamul,

I am using the 877A for the rx but I disconnected it while I was trying to get the circuit working, will the valid transmission LED not work with it disconnected ?

thanks
Acestu

[Enamul]

Hi

I am not quite clear what you have done and where you stuck. Did you manage to sort TX +E and RX+D without PIC IC? If so, you can try with PIC with the programs I posted. The program is actually checked whether the PIC+E+TX transmits the data (138) and the RX+D+PIC receives the same 138 data. If so, it will turn a LED in PIC pin.

You can see data 138 in calculation box of TX, 10001010 and in receiver I have checked whether the received byte is 138 or not.

[acestu]

Hi Enamul,

On the TX side the transistor is switching transmitter power on and at the RX side if I put an led on the receiver data line it lights up but I cannot get the VT led to light up

Thanks
Acestu

[Enamul]

VT should always be high...should only blink when new data appears

[acestu]

Hi Enamul,

I have sorted it out:

http://www.youtube.com/watch?v=YsaddmEG5Ok

I was taking your circuit diagram as literal and not by the pin numbers anyway I rewired it and now it is working.

Thanks
Acestu

[Enamul]

Good work. Now if you add LM35DZ to the PIC connected to TX & E. If you look for higher accuracy you can use LM358 op-amp as non-inverting amplifier. Instead of sending 138 we can send adc value to display in LCD as Temp.

[acestu]

Hi Enamul,

I have those components but not sure where to start really, what do you recommend I do next ?

thanks
Acestu

[Enamul]

Hi
Here is the diagram with LM35dz sensor with PIC16f870. I have changed power control transistor and data out of PIC. If your circuit is ready let me know. I will send you the modified code.

[acestu]

Hi Enamul,

I have put the LM35DZ circuit together ,

http://www.youtube.com/watch?v=xC1EDY8JHro


Do I remove the wire from AN0 on the 16f870 that goes to the D0 (pin 10) of the HT-12E and
connect the new pin 7 of the 358 to it ?

thanks
Acestu