add schematic pdfs and firmware code

Code/thermal_printer/utils.c

@@ -0,0 +1,21 @@
+#include "utils.h"
+
+void delayus(unsigned int _us){
+  delayMicroseconds(_us);
+}
+
+uint8_t invert_bit(uint8_t a){
+
+  return ((a&0x01)<<7)|((a&0x02)<<5)|((a&0x04)<<3)|((a&0x08)<<1)|((a&0x10)>>1)|((a&0x20)>>3)|((a&0x40)>>5)|((a&0x80)>>7);
+  
+}
+
+uint8_t bits_number(uint8_t n)//count bits "1"
+{ 
+    uint8_t count = 0; 
+    while (n) { 
+        count += n & 1; 
+        n >>= 1; 
+    } 
+    return count; 
+}