Test release(unfinished, but usable, I think)

MultiMAX6675.cpp

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+#include "MultiMAX6675.h"
+
+void MultiMAX6675::begin(SPIClass * spi) {
+  current_millis = millis();
+  this->spi = spi;
+}
+
+void MultiMAX6675::loop() {
+  current_millis = millis();
+  std::size_t queue_size = read_queue.size();
+  if(queue_size == 0) return;
+  for(uint16_t i = read_queue_free_on_beginning; i < queue_size; i++) {
+    QueueItem item = read_queue[i];
+    if(current_millis >= item.read_on) {
+      digitalWrite(item.pin, LOW);
+      spi->beginTransaction(SPISettings(4300000, SPI_MSBFIRST, SPI_MODE0));
+      // [bit, description] - [0, dummy sign bit][1-12, the data we want, a 12-bit unsigned number(0-4096)][13, thermocouple input][14, device id][15, state]
+      // I have no idea what the last 3 bits are for, so just shift them. lol 
+      float temperature = (spi->transfer16(0) >> 3) / 4.0;
+      spi->endTransaction();
+      digitalWrite(item.pin, HIGH);
+      *item.var = item.unit == Unit::CELCIUS ? temperature : ((1.8 * temperature) + 32);
+      if(queue_size - 1 == i) {
+        read_queue.pop_back();
+      } else {
+        read_queue_free_on_beginning = i;
+      }
+    }
+  }
+}
+
+unsigned int MultiMAX6675::add(uint8_t CS_PIN) {
+  pinMode(CS_PIN, OUTPUT);
+  digitalWrite(CS_PIN, HIGH);
+  cs_pins.push_back(CS_PIN);
+  return cs_pins.size() - 1;
+}
+
+void MultiMAX6675::read(Unit unit, uint8_t pin_index, float * var) {
+  digitalWrite(cs_pins[pin_index], LOW);
+  digitalWrite(cs_pins[pin_index], HIGH);
+  // delay(220);
+  QueueItem item = QueueItem { .read_on = current_millis + 220, .pin = cs_pins[pin_index], .var = var, .unit = unit};
+  if(read_queue_free_on_beginning == 0) {
+    read_queue.push_back(item);
+  } else {
+    read_queue[read_queue_free_on_beginning] = item;
+    read_queue_free_on_beginning--;
+  }
+}

MultiMAX6675.h

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+#ifndef MULTIMAX6675_H
+#define MULTIMAX6675_H
+
+#include <Arduino.h>
+#include <SPI.h>
+#include <vector>
+#include <array>
+
+enum Unit {
+  CELCIUS,
+  FAHRENHEIT
+};
+
+struct QueueItem {
+  unsigned long read_on;
+  uint8_t pin;
+  float * var;
+  Unit unit;
+};
+
+class MultiMAX6675 {
+  public:
+    void begin(SPIClass * spi);
+    uint32_t add(uint8_t cs);
+    void read(Unit unit, uint8_t pin_index, float * var);
+    void loop();
+  private:
+    SPIClass * spi;
+    std::vector<uint8_t> cs_pins;
+    std::vector<QueueItem> read_queue;
+    uint16_t read_queue_free_on_beginning = 0;
+    unsigned long current_millis;
+    bool start_read = false;
+};
+
+#endif

README.md

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+# MultiMAX6675
+---
+### A simple Arduino library that allows you to **non-blocking(ly)** read MAX6675 K-Type Thermocouple Sensor.
+
+## **Library is still in-progress, if you get any bugs, please open an issue.**
+
+## Todo
+### - add errors when thermocouple is not connected.
+### - optimizations
+
+## Example Usage
+```c++
+#include <Arduino.h>
+#include <SPI.h>
+#include <MultiMAX6675.h>
+
+// Pins, modify accordingly.
+
+#define SPI_SCLK 27
+#define SPI_MISO 25
+#define TC1_CS 26
+#define TC2_CS 14
+
+MultiMAX6675 thermocouples;
+
+uint8_t thermocouple2_index;
+uint8_t thermocouple1_index;
+
+void setup() {
+  Serial.begin(9600);
+  // Initialize SPI, or create your own SPIClass.
+  // It is assumed that they all share the same SPI Bus.
+  SPI.begin(SPI_SCLK, SPI_MISO);
+  thermocouples.begin(&SPI); // Takes a pointer to an SPIClass
+
+  thermocouple1_index = thermocouples.add(TC1_CS); // Takes a CS(Chip Select) pin of the thermocouple, returns an index. Either save the index to a variable, or you don't have to if you already know the order.
+  thermocouple2_index = thermocouples.add(TC2_CS);
+}
+
+float thermocouple1_temperature;
+float thermocouple2_temperature;
+
+unsigned long prev = 0;
+
+void loop() {
+  // [Unit::CELCIUS, Unit::FAHRENHEIT][Thermocouple Index, look above][Pointer to a float, where you want to save the temperature.]
+  // You can ONLY read every 250ms(preferably a bit more), in order to not run out of memory(?), due to sensor limitation, resulting in a crash. Use millis() to do so, otherwise, what's point of this library. xD
+  if(millis() >= (prev + 300)) {
+    prev = millis();
+    thermocouples.read(Unit::CELCIUS, thermocouple1_index, &thermocouple1_temperature);
+    thermocouples.read(Unit::CELCIUS, thermocouple2_index, &thermocouple2_temperature);
+    Serial.println(thermocouple1_temperature);
+    Serial.println(thermocouple2_temperature);
+  }
+  thermocouples.loop(); // Call this as often as possible.
+}
+```

examples/Read/Read.ino

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+#include <Arduino.h>
+#include <SPI.h>
+#include <MultiMAX6675.h>
+
+// Pins, modify accordingly.
+
+#define SPI_SCLK 27
+#define SPI_MISO 25
+#define TC1_CS 26
+#define TC2_CS 14
+
+MultiMAX6675 thermocouples;
+
+uint8_t thermocouple2_index;
+uint8_t thermocouple1_index;
+
+void setup() {
+  Serial.begin(9600);
+  // Initialize SPI, or create your own SPIClass.
+  // It is assumed that they all share the same SPI Bus.
+  SPI.begin(SPI_SCLK, SPI_MISO);
+  thermocouples.begin(&SPI); // Takes a pointer to an SPIClass
+
+  thermocouple1_index = thermocouples.add(TC1_CS); // Takes a CS(Chip Select) pin of the thermocouple, returns an index. Either save the index to a variable, or you don't have to if you already know the order.
+  thermocouple2_index = thermocouples.add(TC2_CS);
+}
+
+float thermocouple1_temperature;
+float thermocouple2_temperature;
+
+unsigned long prev = 0;
+
+void loop() {
+  // [Unit::CELCIUS, Unit::FAHRENHEIT][Thermocouple Index, look above][Pointer to a float, where you want to save the temperature.]
+  // You can ONLY read every 250ms(preferably a bit more), in order to not run out of memory(?), due to sensor limitation, resulting in a crash. Use millis() to do so, otherwise, what's point of this library. xD
+  if(millis() >= (prev + 300)) {
+    prev = millis();
+    thermocouples.read(Unit::CELCIUS, thermocouple1_index, &thermocouple1_temperature);
+    thermocouples.read(Unit::FAHRENHEIT, thermocouple2_index, &thermocouple2_temperature);
+    Serial.println(thermocouple1_temperature);
+    Serial.println(thermocouple2_temperature);
+  }
+  thermocouples.loop(); // Call this as often as possible.
+}

keywords.txt

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+MultiMAX6675 KEYWORD1
+begin KEYWORD2
+add KEYWORD2
+read KEYWORD2

library.properties

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+name=MultiMAX6675
+version=0.0.1
+author=Shuncey <[email protected]>
+maintainer=Shuncey <[email protected]>
+sentence=Read multiple MAX6675 sensor non-blocking(ly)
+paragraph=A simple Arduino library that allows you to non-blocking(ly) read MAX6675 K-Type Thermocouple Sensor.
+category=Sensors
+url=https://github.com/shunceyb/MultiMAX6675
+architectures=*
+includes=MultiMAX6675.h
+depends=