Fixed #3 Allow negative values

Source/TODO

@@ -1,19 +0,0 @@
-Code:
-
-x After turning off, turning on doesn't really respond well to the option button
-- Store value in EEPROM (after a timeout)
-- Long press shows menu with reset option (menu prevents accidental resets and can show battery voltage)
-
-
-PCB:
-
-- Bigger pads for the +5V vias
-
-
-
-
-Pin-out reminder:
-
-SW2 = -     = pin 2, PB3
-SW3 = menu  = pin 3, PB4
-SW1 = +     = pin 6, PB1

Source/res/digits2code.py

@@ -74,23 +74,24 @@ while x < width:
     x += 1
 
   digitWidth = x - startX
-  if digitWidth > maxWidth:
+
+  # Only measure actual digits for the maximum, skip the minus sign
+  if len(digits) > 0 and digitWidth > maxWidth:
     maxWidth = digitWidth
 
   digits.append({ "start": startX, "stop": x, "width": digitWidth })
   x += 1
 
 
-if len(digits) != 10:
+if len(digits) != 11:
-  print("Error: expected 10 digits, found", len(digits))
+  print("Error: expected 11 sections (minus sign + 10 digits), found", len(digits))
   exit(2)
 
 rows = int(math.ceil(height / 8))
 
-print("Found 10 digits")
+print("Character width    :", maxWidth)
-print("  character width    :", maxWidth)
+print("Rows per character :", rows)
-print("  rows per character :", rows)
+print("Total bytes        :", rows * maxWidth * 10)
-print("  total bytes        :", rows * maxWidth * 10)
 
 
 output = open(OutputHeaderFile, "w")
@@ -103,8 +104,12 @@ output.write("#define DigitWidth " + str(maxWidth) + "\n")
 output.write("#define DigitHeight " + str(height) + "\n")
 output.write("#define DigitRows " + str(rows) + "\n")
 output.write("#define DigitBytesPerChar " + str(rows * maxWidth) + "\n")
+output.write("\n")
+output.write("#define MinusSignWidth " + str(digits[0]["width"]) + "\n")
+output.write("#define MinusSignBytes " + str(rows * digits[0]["width"]) + "\n")
 output.write("\n\n\n")
 output.write("extern const uint8_t Digits[] PROGMEM;\n")
+output.write("extern const uint8_t MinusSign[] PROGMEM;\n")
 output.write("\n")
 output.write("#endif\n")
 output.close();
@@ -124,7 +129,7 @@ def outputColumn(value, isLast):
 
 
 # Generate byte array for each digit
-for digitIndex in range(len(digits)):
+for digitIndex in range(1, len(digits)):
   digit = digits[digitIndex]
   output.write("  // " + str(digitIndex) + "\n")
 
@@ -150,7 +155,25 @@ for digitIndex in range(len(digits)):
     output.write("\n")
   output.write("\n")
 output.write("};\n")
+output.write("\n");
+
+
+output.write("const uint8_t MinusSign[] PROGMEM = {\n")
+digit = digits[0]
+
+for rowIndex in range(rows):
+  lastRow = rowIndex == rows - 1
+  output.write("  ")
+
+  # Output one column at a time
+  for x in range(digit["start"], digit["stop"]):
+    outputColumn(getColumnValue(x, rowIndex * 8), lastRow and x == digit["stop"] - 1)
+
+  output.write("\n")
+
+output.write("};\n")
 output.close()
 
+
 print("")
 print("Wrote output to", OutputHeaderFile, "and", OutputCodeFile)

Source/src/digits.c

@@ -1,7 +1,7 @@
 #include "digits.h"
 
 const uint8_t Digits[] PROGMEM = {
-  // 0
+  // 1
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0xfc, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x80, 0xf0, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3f, 0x0f, 0x07, 0x07, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x07, 0x1f, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfc, 0xf0, 0x80, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1f, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0x00, 
@@ -11,7 +11,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x01, 0x0f, 0x3f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x3f, 0x0f, 0x01, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x3f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x0f, 0x07, 0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 1
+  // 2
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x7c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x03, 0x07, 0x0f, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -21,7 +21,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 2
+  // 3
   0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0xfc, 0xfc, 0xf8, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x10, 0x7e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x3f, 0x1f, 0x0f, 0x07, 0x07, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x0f, 0x0f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xf0, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x01, 0x07, 0x0f, 0x3f, 0x1f, 0x0f, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0f, 0x00, 0x00, 0x00, 
@@ -31,7 +31,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x80, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xf8, 0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0x3f, 0x00, 0x00, 
   0x00, 0x3f, 0x7f, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x0f, 0x07, 0x01, 0x00, 0x00, 0x00, 
 
-  // 3
+  // 4
   0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0x7c, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x3f, 0x1f, 0x1f, 0x1f, 0x0f, 0x0f, 0x0f, 0x0f, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x87, 0xe7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x3f, 0x0f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -41,7 +41,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x80, 0xe0, 0xf0, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x07, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x1f, 0x3f, 0x3f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x1f, 0x0f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 4
+  // 5
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0x7e, 0x3e, 0x1e, 0x0e, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xe0, 0xf0, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x3f, 0x0f, 0x07, 0x03, 0x01, 0x00, 0x00, 0x80, 0xc0, 0xc0, 0xe0, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe0, 0xf8, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x0f, 0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 0x80, 0xe0, 0xf8, 0xfe, 0xff, 0xff, 0xff, 0xff, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -51,7 +51,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 5
+  // 6
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xf8, 0xfc, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3f, 0x0f, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x0f, 0x0f, 0x0f, 0x0f, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0xe0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x00, 0x00, 0x00, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -61,7 +61,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0xe0, 0xf8, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x07, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x03, 0x07, 0x0f, 0x1f, 0x1f, 0x3f, 0x3f, 0x7f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x3f, 0x1f, 0x0f, 0x0f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 6
+  // 7
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0x7c, 0x1c, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xf0, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x3f, 0x1f, 0x0f, 0x07, 0x07, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x07, 0x0f, 0x1f, 0x0f, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0xc0, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x80, 0x80, 0x80, 0x80, 0xc0, 0xc0, 0xc0, 0xc0, 0xc0, 0x80, 0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -71,7 +71,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x07, 0x1f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfc, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xfc, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x03, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x1f, 0x3f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x0f, 0x0f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 7
+  // 8
   0x00, 0x00, 0x00, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfc, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0x7f, 0x3f, 0x1f, 0x0f, 0x0f, 0x0f, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0xc7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3f, 0x1f, 0x07, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xe0, 0xf0, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
@@ -81,7 +81,7 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0xf0, 0xe0, 0xc0, 0x80, 0x80, 0x80, 0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x0f, 0x1f, 0x3f, 0x3f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x3f, 0x1f, 0x1f, 0x07, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 
-  // 8
+  // 9
   0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0xfc, 0xfc, 0xf8, 0xf0, 0xf0, 0xe0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0xf0, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1f, 0x0f, 0x07, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xf8, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xe0, 0xc0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x03, 0x00, 0x00, 0x00, 0x00, 
@@ -91,7 +91,7 @@ const uint8_t Digits[] PROGMEM = {
   0x0f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfc, 0xfc, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xfc, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x03, 0x00, 
   0x00, 0x00, 0x01, 0x03, 0x07, 0x0f, 0x0f, 0x1f, 0x3f, 0x3f, 0x3f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x1f, 0x0f, 0x07, 0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 
 
-  // 9
+  // 10
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xe0, 0xf0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0xfc, 0xfc, 0xf8, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
   0x00, 0x00, 0xc0, 0xf8, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x0f, 0x07, 0x07, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x07, 0x07, 0x0f, 0x1f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xf8, 0xc0, 0x00, 0x00, 0x00, 
   0x00, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xc0, 0x00, 
@@ -102,3 +102,14 @@ const uint8_t Digits[] PROGMEM = {
   0x00, 0x00, 0x00, 0x00, 0x38, 0x3f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x1f, 0x0f, 0x0f, 0x07, 0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 
 };
+
+const uint8_t MinusSign[] PROGMEM = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0xe0, 0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0x38, 
+  0x07, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x07, 0x01, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};

Source/src/digits.h

@@ -8,8 +8,12 @@
 #define DigitRows 8
 #define DigitBytesPerChar 328
 
+#define MinusSignWidth 19
+#define MinusSignBytes 152
+
 
 
 extern const uint8_t Digits[] PROGMEM;
+extern const uint8_t MinusSign[] PROGMEM;
 
 #endif

Source/src/screen/counter.c

@@ -5,13 +5,17 @@
 #include "../buttons.h"
 
 
-uint16_t lastDrawnCounter = 9999;
+#define CounterMinValue -99
-uint16_t counter = 0;
+#define CounterMaxValue 999
+
+int16_t lastDrawnCounter = 9999;
+int16_t counter = 0;
 
 
 // Forward declarations
-void drawCounter(uint16_t value);
+void drawCounter();
 void drawDigit(uint8_t* column, uint8_t digit);
+void drawMinusSign(uint8_t* column);
 void blankDigitColumn(uint8_t* column, uint8_t width);
 
 
@@ -19,54 +23,75 @@ void handleCounterScreen()
 {
   if (button_is_pressed_or_repeated(&buttonUp))
   {
-    if (counter < 999)
+    if (counter < CounterMaxValue)
       counter++;
   }
   else if (button_is_pressed_or_repeated(&buttonDown))
   {
-    if (counter > 0)
+    if (counter > CounterMinValue)
       counter--;
   }
 
   if (counter != lastDrawnCounter || getScreenInvalidated())
   {
-    drawCounter(counter);
+    drawCounter();
     lastDrawnCounter = counter;
   }
 }
 
 
-void drawCounter(uint16_t value)
+void drawCounter()
 {
-  if (value > 999) value = 999;
   uint8_t column = DigitFullOffset;
 
-  if (value < 10)
+  if (counter < -9)
   {
-    // Single digit, blank left and right (prevents flicker)
+    // Two digit negative, blank left and right (minimizes flicker) and spacing
+    blankDigitColumn(&column, SpacingNegativeLeft2);
+    drawMinusSign(&column);
+    blankDigitColumn(&column, DigitSpacing);
+
+    drawDigit(&column, (-counter) / 10);
+    blankDigitColumn(&column, DigitSpacing);
+    drawDigit(&column, (-counter) % 10);
+
+    blankDigitColumn(&column, SpacingNegativeRight2);
+  }
+  else if (counter < 0)
+  {
+    // Single digit negative, similar
+    blankDigitColumn(&column, SpacingNegativeLeft1);
+    drawMinusSign(&column);
+    blankDigitColumn(&column, DigitSpacing);
+    drawDigit(&column, -counter);
+    blankDigitColumn(&column, SpacingNegativeRight1);
+  }
+  else if (counter < 10)
+  {
+    // Single digit, blank left and right only
     blankDigitColumn(&column, SpacingLeft1);
-    drawDigit(&column, value);
+    drawDigit(&column, counter);
     blankDigitColumn(&column, SpacingRight1);
   }
-  else if (value < 100)
+  else if (counter < 100)
   {
-    // Two digits, similar but also blank the spacing
+    // Two digits, you know the drill by now
     blankDigitColumn(&column, SpacingLeft2);
 
-    drawDigit(&column, value / 10);
+    drawDigit(&column, counter / 10);
     blankDigitColumn(&column, DigitSpacing);
-    drawDigit(&column, value % 10);
+    drawDigit(&column, counter % 10);
 
     blankDigitColumn(&column, SpacingRight2);
   }
   else
   {
-    // Three digits, you know the drill by now
+    // Three digits
-    drawDigit(&column, value / 100);
+    drawDigit(&column, counter / 100);
     blankDigitColumn(&column, DigitSpacing);
-    drawDigit(&column, (value % 100) / 10);
+    drawDigit(&column, (counter % 100) / 10);
     blankDigitColumn(&column, DigitSpacing);
-    drawDigit(&column, value % 10);
+    drawDigit(&column, counter % 10);
   }
 }
 
@@ -96,6 +121,29 @@ void drawDigit(uint8_t* column, uint8_t digit)
 }
 
 
+void drawMinusSign(uint8_t* column)
+{
+  uint8_t yEnd = DigitPage + DigitRows;
+  uint16_t bitmapOffset = 0;
+
+  for (uint8_t y = DigitPage; y < yEnd; y++)
+  {
+    ssd1306_setpos(*column, y);
+    ssd1306_send_data_start();
+
+    for (uint8_t x = 0; x < MinusSignWidth; x++)
+    {
+      ssd1306_send_byte(pgm_read_byte(&MinusSign[bitmapOffset]));
+      bitmapOffset++;
+    }
+
+    ssd1306_send_data_stop();
+  }
+
+  (*column) += MinusSignWidth;
+}
+
+
 void blankDigitColumn(uint8_t* column, uint8_t width)
 {
   uint8_t yEnd = DigitPage + DigitRows;

Source/src/screen/counter.h

@@ -22,12 +22,22 @@
 #define DigitOffset2 ((DisplayWidth - DigitWidth2) / 2)
 #define SpacingLeft2 ((DigitFullWidth - DigitWidth2) / 2)
 #define SpacingRight2 (DigitFullWidth - DigitWidth2 - SpacingLeft2)
-#define DigitWidth1 DigitWidth
 
+#define DigitNegativeWidth2 (DigitWidth2 + MinusSignWidth + DigitSpacing)
+#define DigitNegativeOffset2 ((DisplayWidth - DigitNegativeWidth2) / 2)
+#define SpacingNegativeLeft2 ((DigitFullWidth - DigitNegativeWidth2) / 2)
+#define SpacingNegativeRight2 (DigitFullWidth - DigitNegativeWidth2 - SpacingNegativeLeft2)
+
+#define DigitWidth1 DigitWidth
 #define DigitOffset1 ((DisplayWidth - DigitWidth1) / 2)
 #define SpacingLeft1 ((DigitFullWidth - DigitWidth1) / 2)
 #define SpacingRight1 (DigitFullWidth - DigitWidth1 - SpacingLeft1)
 
+#define DigitNegativeWidth1 (DigitWidth + MinusSignWidth + DigitSpacing)
+#define DigitNegativeOffset1 ((DisplayWidth - DigitNegativeWidth1) / 2)
+#define SpacingNegativeLeft1 ((DigitFullWidth - DigitNegativeWidth1) / 2)
+#define SpacingNegativeRight1 (DigitFullWidth - DigitNegativeWidth1 - SpacingNegativeLeft1)
+
 
 extern void handleCounterScreen();