Please help me with the ds18b20 sensor.

[Jury]

Hi. I'm just a beginner. I can't get the ds18b20 to work. I wrote the code as described in the help. Besides, I watched the video here. https://www.youtube.com/watch?v=iBojUPEJO2g
And that's where it works. But I don't. If I use ReadDigitalTemp, the display shows 0.0625. And if readtemp, then the display is 128. Here is my code. What am I doing wrong?

[Anobium]

https://github.com/Anobium/Great-Cow-BASIC-Demonstration-Sources/tree/master/Temperature_Sensor_Solutions/DS18B20_Sensor_Solutions/Sensor_to_Software_Serial_Terminal

There are many working demos on GitHub.

[Jury]

I've seen it. Moreover, I copied the code from there for mega328. I couldn't get him to work either.
And I would like to understand what is wrong with my code?

[Roger Jönsson]

What is PC3? How about:
#define DQ PortC.3

[Anobium]

@Jury

Post the ASM file being generated. I want to see the version of the compiler in use.

---

So, you have the I2C LCD working. That is good.
PC3 should work as the port. As this resolves to PORTC.3

---

[Anobium]

A quick search of the demos shows many published/verified demos.

PS C:\GCstudio\gcbasic\demos> Get-ChildItem -Recurse -File |
>>     Where-Object {
>>         (Select-String $_.FullName -Pattern '(?i)\bmega\w*\b' -Quiet) -and
>>         (Select-String $_.FullName -Pattern '(?i)DS18B20' -Quiet)
>>     } |
>>     Select-Object -ExpandProperty FullName
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_ROM_Read_to_LCD\DS18B20_ROM_Read_to_LCD_1Wire_supporting_LCD_IO_0_mega168.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_ROM_Read_to_LCD\DS18B20_ROM_Read_to_LCD_1Wire_supporting_LCD_IO_10_mega328p.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_GLCD\Temperature_Sensor_to_GLCD_mega168.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_Hardware_Serial_Terminal\Temperature_Sensor_to_Hardware_Serial_Terminal_mega168.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_Hardware_Serial_Terminal\Temperature_Sensor_to_Hardware_Serial_Terminal_mega328P.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_LCD\4Wire_LCD\Temperature_Sensor_to_LCD_mega168.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_LCD\I2C_LCD\Temperature_Sensor_to_Software_I2C_LCD_mega328p.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_LCD\I2C_LCD\Temperature_Sensor_to_Software_I2C_Multiple_LCDs_mega328p.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_Software_Serial_Terminal\Temperature_Sensor_to_Software_Serial_Terminal_mega168.gcb
C:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_to_Software_Serial_Terminal\Temperature_Sensor_to_Software_Serial_Terminal_mega328p.gcb

Let me see the ASM.

[Jury]

My GCBasic\demos folder looks like this

[Anobium]

Re the empty(ish) demo folder. Download and install the Demo Pack shown on GCSTUDIO startup application.

---

ASM looks ok in terms of updates. Yes, there are later builds but this is the recent general release build.

---

Things that you can verify for me.

LCD shows strings and values. This tells me the I2C hardware is working.

Do a operation. What DSData return?

You have a 4k7 pullup from the Portc.3 to 5v0 as per the device datasheet.

There are no errors shown when compiling.

Has this circuit worked with another compiler?

---

Things I do know.

Your code works in a Simulator.

There are many working demos. But, this is not to say that in this specific use case there is not an error. :-)

---

Evan

[Jury]

I2C is working. If I output any text, it is displayed correctly on the screen. ReadDigitalTemp displays a value of 0.0625. A 4.7K resistor is present, according to the datasheet. I have not used another compiler. Which compiler should I try?

[Anobium]

Was not recommending another compiler. This is a very good toolchange.

---

As you are get 0.0625 back this means that the values obtained by the read routines equate to 1
And, that would be very cold.

What did DSData return on the LCD?

Check you have that 4k7 connected correctly. Post a foto of the setup.

[Anobium]

Minimum code to read the sensor would be. This should return the raw value. Depends what this returned will determine the next step.

Do forever

    DS18B20DeviceRead
    CLS 
    Print DSDATA
    wait 1 s

 Loop

[Jury]

I can take a photo if necessary, but I'm not sure if it will help. There's a bunch of wires with a minimum board for the atmega8. A 4.7k resistor is connected between the red and yellow wires. I've attached a drawing. This sensor works correctly when connected to the arduino.
Your code returns 65535.

[Anobium]

Arduino is another compiler. That is good to know it works with this setup.

But, with this exact setup, these connections/pinout?

---

This is puzzling. As it works on simulation.

[Jury]

I made a circuit with an analog LM335 sensor with output to an LED display. Everything is working as it should. But I can't get the ds18b20 to work.
I took the code from here.
c:\GCstudio\gcbasic\demos\Temperature_Sensor_Solutions\DS18B20_Sensor_Solutions\Sensor_ROM_Read_to_LCD\DS18B20_ROM_Read_to_LCD_1Wire_supporting_LCD_IO_10_mega328p.gcb
Just changed atmega328 to atmega8. I have installed the Proteus Free Trial.

Got this.

[Anobium]

OK.

What did this return? DSDATA specificially

Do forever

DS18B20DeviceRead
CLS 
Print DSDATA
wait 1 s

Loop

[Jury]

that is

[Anobium]

Oh. This is not on real silicon? Real hardware?

[Jury]

No, it's a simulator. I'll try it on a real microcontroller later.

[Anobium]

I just had a look at the library.

As the Arduino runs at much slower speeds ( it does ) then you may have to add some delays into the library.

Give me 30 mins to change the library.

[Jury]

You gave me an idea. I configured the atmega8 to run at 16 MHz. And, unexpectedly, the sensor showed the correct temperature. After that, I tried an 8 MHz configuration. At this frequency, the sensor also shows the correct temperature. Then I reduced the frequency to 4 MHz and got a result of 0.0625. The atmega8 default configuration runs at 1 MHz.
So, the conclusion is that the code doesn't work at low frequencies.

[Anobium]

Try the code below. I want to know if this resolves at these other frequencies.

[Jury]

If I add this code, the display is empty

And yes, if you explicitly specify the frequency as 1MHz in the original code, it also works. I didn't know that if you don't explicitly specify the frequency, it takes the highest possible value.

[Anobium]

Add what code?

[Jury]

Here on the real hardware. Only it's not an Arduino, it's just an atmega8.

[Anobium]

So.,the value equates to -1.

I do not have a device here, but, I see that that the library has been optimised for speed.

Add the following to your program. This will be called replacing the existing the library sub routine.

This is restores the time delays.

Test please.

Sub DS18B20DeviceRead
  ' This routine makes available a variable called DSdata
  ' DSdata is the raw data value from the sensor

   wait 250 ms ' Not really needed but left in just in case ***
   MasterRST   ' Reset ds18b20
   PPulse      ' Request a presence pulse
   wait 1 ms
   OWout SkipRom  ' Bypass ds18b20 serial number read
   wait 1 ms
   OWout ConvertT  ' Instruct ds18b20 to begin temperature conversion to digital
   Do
                dir DQ out
                Set DQ Off
                wait 4 us
                Dir DQ In
                wait 7 us
                If DQ = 1 Then Exit Do
                wait 60 us    'minimum 60 us time slots between reads
   Loop

   MasterRST
   PPulse
   wait 1 ms
   OWout SkipRom         ' Bypass ds18b20 serial number read
   wait 1 ms
   OWout ReadScratch     ' Read temperature from db18b20
   wait 1 ms
   Owin                  ' Receive temperature low byte from db18b20
   DSdata = RxData       ' First byte  is low byte
   wait 1 ms
   Owin                  ' Receive temperature high byte from db18b20
   DSdata_H = RxData     ' Second byte is high byte  (auto combined into 16 bit word)
end sub