Arduino Mega 2560 Rev3 + eight or more MAX6675 modules + SD card reader

Projects General Guidance
1

Dear all,

I am new to Arduino but I am excited to see what everyone is doing with this great piece of kit.

I am working on a small project where I want to monitor temperatures in the exhaust pipe over the pipe length. I need to mount at least 8 (12 is preferred) K type thermocouples. For this I want to use MAX6675 module with K type thermocouples.

I hope you can help me in answering my questions:

1. What is the maximum amount of MAX6675 modules I can mount to Arduino Mega 2560?

2. How do I connect these MAX6675 modules? Which pins I use for this? I am struggling to understand which pin is what and what I can use for my purpose on the Arduino board.

3. What is the maximum (fastest) sampling rate I can achieve with 8 (or 12) channels?

4. How well synchronised in time will be the measurements from 8 (12) channels?

5. Can you please advise on the smart way of programming this setup so the delay between each thermocouple is minimised?

6. If there is no option to connect 8 MAX6675 modules how can I synchronise two or more Arduinos to have all the sensors data in the same time scale.

Thank you,
Matt

2

  1. A crapload of them. You've got more pins than you can shake a stick at on the '2560, you're l

  2. SCK, MISO get connected to SCK, SO respectively. All of them share these connections - all the SCK's are connected together.

  3. Datasheet indicates a conversion takes 0.17 to 0.22 seconds - that's how often you can read the sensors and get a new value.

  4. They will be read when you read them. since the conversion time is long relative to the time it takes to process them, they'll all be read at about the same time.

  5. Just read them right after eachother, and don't do anything inbetween.

  6. No need.

3

Thank you for the quick response.

In this case I order my kit :slight_smile: