add schematic pdfs and firmware code

Code/thermal_printer/utils.h

@@ -0,0 +1,23 @@
+#ifndef UTILS_H
+#define UTILS_H
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h> 
+#include <string.h>
+
+#include <wiringPi.h>
+
+#define SEP printf(" ");
+// a is string, b is number
+#define DEBUG(a,b) printf(a);SEP;printf("%d\n",b);
+
+#define ALINE printf("\n");
+
+void delayus(unsigned int _us);
+
+uint8_t invert_bit(uint8_t a);
+
+uint8_t bits_number(uint8_t n);
+
+
+#endif