MAX6675 Module and SD Card Module Pin Connections and Arduino Mega

[scyp101]

Hello!

We have a project where we would like to use 6x "MAX6675 Module + K Type Thermocouple Sensor" (exactly the ones shown in this link: https://digilog.pk/products/max6675-module-k-type-thermocouple-sensor-sensor-in-pakistan). We would also be adding an LCD or two depending on the amount of text. We will probably go with LCD displays that are I2C compatible.

Now, there are 2 problems that we are facing:

1. Problem number 1 is with the storage. We would like to have the sensors take readings every 20 minutes and store the temperature data somewhere. Due to the amount of data, we have opted for an SD card module (precisely this one: https://digilog.pk/products/arduino-sd-card-reader-module-in-pakistan).
   .
   As per the pin configuration, we need 2 MISO and 2 SCK pins. 1 MISO and 1 SCK pin for all the thermocouples (overlapping these common pins for all sensors) and 1 MISO and 1 SCK pins for the SD card reader. What we are facing is that all MISO pins and SCK pins on the 6x thermocouples can be overlapped but they can’t be overlapped with the MISO and SCK pin on the SD card reader. The problem is here since we require 2 MISO and SCK pins and the Arduino we have researched all have 1 pin. What should we do?
   .
   We have tried overlapping the MISO and SCK pins for the thermocouple and the SD card reader. The SD Card code works fine but the thermocouples doesn’t work. They show no temperature value. When we comment out the SD card code, the thermocouple works fine.

2. Problem number 2 is with the amount of pins. As per our requirements, we need atleast 25 pins more or less (I am uncertain if we could utilize the analog pins anyhow). If anyone reading this have worked with something similar, could you please confirm or give your input on this matter? Does Arduino Mega work for us?

Any comment will be greatly appreciated. If I am missing something, please also do tell me that.

Note: I would also like to point out that this is not our field of working so if this is something easy please do let me know.

This is an image of the pin configuration for the MAX6675 module.

This is an image of the pin configuration for the SD Card module.

[horace]

there are many reports of other devices not working on the same SPI bus with common SD card readers, see Sharing the SPI bus among SD card and other SPI devices
consider using a microcontroller with multiple SPI interfaces,, e.g. ESP32 see connecting-sd-card-and-bmp280-via-spi-interface