Atmega4808, one wire & DS18B20

Using Arduino Microcontrollers
1

I’m trying to use DS18B20 temperature sensors with an Atmega4808 using PIN_PD6 and it just does not work!

I’ve used the sensor on an UNO, using this: Guide for DS18B20 Temperature Sensor with Arduino | Random Nerd Tutorials and I can easily read the temperature.

I replaced the UNO with a 4808 (on my PCB), and just get nothing. I used a scope to measure the DQ pin, and cannot see any communication.
If I use blink on PIN_PD6 I see the single changing.

Did many search on this and found this:

But doesn’t help to solve the issue.

How can I get the sensor to work with my PCB?

2

Can you explain this statement. An UNO is a board with a 328P micro on it, but a 4808 is a chip.

How have you replaced one with the other?

1 Like
3

Post an annotated schematic of your circuit, show all connections including power, ground, and power sources.

4

It might help if you mentioned which core and which board you're compiling against (i.e. the FQBN).

5

Sorry for the missing information!

What I meant was that I tested the DS18B20 using a UNO board in the "normal mode" (5V to the VDD as seen in the link I sent):

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image994×632 116 KB

I used the "One wire" and "dallas" libraries and the arduino code (single sensor) as in the link I sent.
This works fine.

I then disconnected the UNO and connected my 4808 board (32pin) which has the MegaCoreX.
I just updated the sensor pin to:
#define ONE_WIRE_BUS PIN_PD6

/*********
  Rui Santos
  Complete project details at http://randomnerdtutorials.com  
  Based on the Dallas Temperature Library example
*********/
#include <OneWire.h>
#include <DallasTemperature.h>

#define ONE_WIRE_BUS PIN_PD6
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

void setup(void)
{
  Serial.begin(9600);
  sensors.begin();
}

void loop(void){ 
  sensors.begin();
  sensors.requestTemperatures(); 
  Serial.print("T=");
  Serial.println(sensors.getTempCByIndex(0)); 
  delay(1000);
}

But this does not work. and I don’t see any communication when probing DQ leg with my oscilloscope.

As I can figure out, there is something that does not work with the "one wire" and the 4808.

I hope this has all the missing information.

6

I have no idea what I did today different than yesterday (probably it’s better to work after a good night sleep), but now I got it working!!

According to Add line for Atmega4808 · Issue #99 · PaulStoffregen/OneWire · GitHub

In OneWire_direct_gpio.h I changed

#if defined(__AVR_ATmega4809__)

To

#if defined(MEGACOREX)

And now it works on my 4808!!!