Having issues connection 4 max6675 sensors to an Arduino atmega 2560

Projects General Guidance
1

I'm very new to the Arduino community, and am having some major issues connecting 4 max6675 thermocouple sensors to my Arduino atmega 2560. My goal is to have each sensor reading different temperatures from different parts of my project, then displayed on a 2x16 lcd with a button to cycle through the different tempetures.

So far, I've wired the screen, and one max6675 to the Arduino, and got it to read temperature using code from ladyada. I've been trying to connect two max6675 sensors, but have been running into issues. From what I've read, I need to change the 7 bit address, but have absolutely no idea how to do that, or if its even possible.

I also plan to add a VNH2SP30 to the Arduino, but I haven't tried that yet, so I have no questions about it, and hopefully won't. Just thought I'd throw that out there.

2

Ashlen:
I'm very new to the Arduino community, and am having some major issues connecting 4 max6675 thermocouple sensors to my Arduino atmega 2560. My goal is to have each sensor reading different temperatures from different parts of my project, then displayed on a 2x16 lcd with a button to cycle through the different tempetures.

So far, I've wired the screen, and one max6675 to the Arduino, and got it to read temperature using code from ladyada. I've been trying to connect two max6675 sensors, but have been running into issues. From what I've read, I need to change the 7 bit address, but have absolutely no idea how to do that, or if its even possible.

I also plan to add a VNH2SP30 to the Arduino, but I haven't tried that yet, so I have no questions about it, and hopefully won't. Just thought I'd throw that out there.

The Max6675 uses SPI communications, Each SPI device requires an individual CS pin (chipSelect), so for your 4 MAX6675 you will wire:

  • MISO from the MEGA to Each of the Four MAX6675 SO (pin 7)
  • SCK from the MEGA to Each of the Four MAX6675 SCK (pin 5)
  • on Each individual MAX6675 CS (pin6) you will assign it it's own Arduino pin for CS
    Arduino Pin 10 for the First Max6675 CS (pin 6)
    Arduino Pin 9 for the Second Max6675 CS (pin 6)
    Arduino Pin 8 for the Third Max6675 CS (pin 6)
    Arduino Pin 7 for the Fourth Max6675 CS (pin 6)

The CS pin is how you select each temperature Sensor.

Chuck.