Dual temp LCD display output

[1-3-2-4]

I was looking at this project online which seemed pretty simple only thing is it has no hex code but uses the PIC chip. I just really need to monitor one area and that's the outside air temp.

the link to the project is here

PIC Dual Temperature Meter

Is this something doable for someone who has never messed with hex code before?

 

[blueroomelectronics]

If you want to build it exactly as shown you don't need to modify the .hex file. BUT if you want to do something different or make changes you need the source file.

 

[1-3-2-4]

If you want to build it exactly as shown you don't need to modify the .hex file. BUT if you want to do something different or make changes you need the source file.

I can't just buy a PIC16F628 from mouser and expect it to display like that right? That's why I was asking about the hex file. but if that's not needed then that's better

 

[blueroomelectronics]

No the 16F628 will arrive blank, you need a PIC programmer like my Junebug kit or a PICkit2 to "burn" the .hex file onto the 16F628.

edit:

My mistake, the project on the page includes a preprogrammed PIC but you must buy it from the site.

 

[1-3-2-4]

No the 16F628 will arrive blank, you need a PIC programmer like my Junebug kit or a PICkit2 to "burn" the .hex file onto the 16F628.

edit:

My mistake, the project on the page includes a preprogrammed PIC but you must buy it from the site.

Ah I see.. so really costs me $65 I don't like the LCD that comes in the kid they have I wanted a Yellow/Green display. oh well... I emailed them anyways to make sure since they talked about upgradable firmware and all.

 

[1-3-2-4]

I have a question does a HEX file allow custom boot screens? I was looking at this LCD again and I noticed the last picture they have a text on the screen. Without the LCD in my hands yet I can't test it but can it be custom every time the LCD turns on it will show the message then the temperature?

 

[ericgibbs]

I have a question does a HEX file allow custom boot screens? I was looking at this LCD again and I noticed the last picture they have a text on the screen. Without the LCD in my hands yet I can't test it but can it be custom every time the LCD turns on it will show the message then the temperature?

hi,
A *.hex file will only function as is.
You could try try to disassemble the hex file.

You need the source file if you want to modify its operation.

 

[1-3-2-4]

Ah ok thanks

 

[1-3-2-4]

ok a little update I started building this kit yesterday and I'm done however when i turn the power on the LCD only shows black boxes from what I hear that means the LCD is not initialized yet.

two things I have a question about in the circuit.. it uses a tact switch to change modes only two leads need to be solder to make a connection?

Also it uses a Dallas DS1820 digital temperature sensor it says it's one wire so for testing only I just hooked up only one wire maybe that's why it's not working right?

 

[1-3-2-4]

**broken link removed**

 

[House0Fwax]

You will need to connect both wires of the sensor for it to work.

For some reason, the diagram shows the 'contrast' pin of the LCD shorted to ground, usually it would be via a pot between power and ground.

 

[ericgibbs]

ok a little update I started building this kit yesterday and I'm done however when i turn the power on the LCD only shows black boxes from what I hear that means the LCD is not initialized yet.

two things I have a question about in the circuit.. it uses a tact switch to change modes only two leads need to be solder to make a connection?
YES
Also it uses a Dallas DS1820 digital temperature sensor it says it's one wire so for testing only I just hooked up only one wire maybe that's why it's not working right?
Two wires [not the +V]

hi,
Looking at the lcd image, I would say the lcd has not been initialised correctly.

Has the PIC been programmed.?

 

[1-3-2-4]

sorry been having a hard time getting to this site not sure why... but the PIC comes pre-programmed.

And Houseofwax not sure why that is as well.. once I know I got it working I will add a pot to adjust it since it will be going in a car.

the sheet you see in the picture lists all the spots where the resistors go like the 10 Ohm between the output of the voltage regulator and the backlight (+) and the two 1K resistors for the temp sensors and a 10k for V+ and the tact switch and the 5.1k for the contrast on the LCD to ground.

Also hooking up the other lead to the temp sensor did no good as well.

 

[3v0]

Add the pot to set the contrast. Without it you will only see black boxes the same as if the LCD was unitialized.

Keep both sides of the temperature sensor hooked up. It is called a 1 wire sensor but that means 1 wire + gnd. So it take two. But the sensor is not your problem yet. It is the pot.

 

[ericgibbs]

hi,
Your image shows the LCD has not been initialised correctly.
Top line is blocks, bottom line is blank.

Check the wiring from PIC to LCD.

I dont see any decoupling, I know its not on the circuit diagram, but I would have added at least a 100nF either side of the 7805 to prevent any instability.

 

[1-3-2-4]

ah a friend told me about the decoupling I have 3 0.1uF caps one goes between the Vin and ground? and the other for Vout and ground of the 7805?

 

[House0Fwax]

the sheet you see in the picture lists all the spots where the resistors go like the 10 Ohm between the output of the voltage regulator and the backlight (+) and the two 1K resistors for the temp sensors and a 10k for V+ and the tact switch and the 5.1k for the contrast on the LCD to ground.

That looks like a different diagram to the one posted on the link in your first post. The component list on the site only mentions 2 1K resistors.

Any chance you could post the diagram you got with the kit?

 

[1-3-2-4]

That looks like a different diagram to the one posted on the link in your first post. The component list on the site only mentions 2 1K resistors.

Any chance you could post the diagram you got with the kit?

here is the one I scanned to the PC

**broken link removed**

 

[bobledoux]

I have never needed a pot to set contrast. But the lack of a decoupling capacitor on the PIC power supply is poor design.

 

[1-3-2-4]

I went ahead and put in two 0.1uf caps for decoupling one for Vin and one for Vout both go to ground. the voltage to the PIC is 5.2v and for the temp sensor I get around 4.2V

here is a picture of the PCB without the LCD connected, the trim pot has not been solder down yet because I don't know should I take out the 5.1K resistor and use the pot or leave that resistor in and put in the pot as well?

**broken link removed**

Also the tact switch when pressed it's in a on state it's a SPST type but should I be getting some kind of voltage reading on it when I press it? Because I don't