Reads the value of a digital caliper and display on VFD

Author: dplassgit

digital_caliper/digital_caliper.ino

@@ -0,0 +1,85 @@
+/**
+   Digital caliper -> VFD
+*/
+
+#include <SPI_VFD.h>
+
+//uint8_t data, uint8_t clock, uint8_t strobe,
+SPI_VFD vfd(3, 6, 4);
+
+const int numRows = 2;
+const int numCols = 40;
+
+#define DC_CLK 11
+#define DC_DATA 10
+
+void setup() {
+  Serial.begin(115200);
+
+  // set up the VFD's number of columns and rows:
+  vfd.begin(numCols, numRows);
+
+  // Print a message to the VFD.
+  vfd.setCursor(0, 0);
+  vfd.print("Hello Digital Caliper");
+  vfd.setCursor(0, 1);
+  vfd.print("Please wait 5 seconds...");
+  vfd.blink();
+  delay(5000);
+  vfd.noBlink();
+  vfd.clear();
+}
+
+int bit_array[25];        // For storing the data bit. bit_array[0] = data bit 1 (LSB), bit_array[23] = data bit 24 (MSB).
+float last = -100000.0;
+
+void loop() {
+  long value = 0, power = 0;
+  int inches = 0;
+  while (digitalRead(DC_CLK) == LOW) {}
+  // it went high, now wait for it to fall.
+  for (int i = 1; i <= 24; ++i) {
+    while (digitalRead(DC_CLK) == HIGH) {}
+    // it fell, read the data.
+    int data = 1 - digitalRead(DC_DATA);
+    bit_array[i] = data;
+    if (i > 1 && i < 21) {
+      // shift data "power" bits to the left, add to value
+      if (data) {
+        value = value + (1L << power);
+      }
+      power++;
+    }
+    if (i == 21 && data == 1) {
+      // sign
+      value = value * -1;
+    }
+    if (i == 24) {
+      inches = data;
+    }
+    // wait for clock to go low again
+    while (digitalRead(DC_CLK) == LOW) {}
+  }
+  for (int i = 1; i <= 24; ++i) {
+    //    Serial.print(i); Serial.print(":"); Serial.println(bit_array[i]);
+  }
+  float actual = value;
+  if (inches == 1) {
+    actual = actual / 1000.0;
+  } else {
+    actual = actual / 50.0;
+  }
+  if (actual != last) {
+    last = actual;
+    vfd.clear();
+    vfd.setCursor(0, 0);
+    vfd.print(actual, 2 + inches);
+    vfd.setCursor(9, 0);
+    if (inches == 1) {
+      vfd.print("in");
+    } else {
+      vfd.print("mm");
+    }
+  }
+  delay(100);
+}