Add protect and unprotect feature

eeprom.py

@@ -60,8 +60,17 @@ class AT28C256(object):
 To load a local file into the EEPROM:
 > [l|load] [filename]
 
-Send a reset command:
-> reset
+To test write/read with random nubers:
+> [t]est
+
+To protect the EEPROM:
+> [p]rotect
+
+To unprotect the EEPROM:
+> [u]nprotect
+
+Quit from program:
+> [q]uit
 
 Address supports hex (0xFF) and octal (0o7) notation.
 """
@@ -128,7 +137,6 @@ def fdump(self, f: IO, size=0x8000, console=sys.stdout) -> None:
             print('\nComplete.', file=console)
 
         if size < 0x8000:
-            self.reset()
             # consume the remaining packet
             self._receive(ack=False)
 
@@ -159,9 +167,13 @@ def fload(self, f: IO, size: int, console=sys.stdout) -> None:
         if console:
             print('\nComplete.', file=console)
 
-    def reset(self) -> None:
-        """Sends a reset command."""
-        self._send(pack('>c', b'r'))
+    def protect(self) -> None:
+        """Protect EEPROM."""
+        self._send(pack('>c', b'p'))
+
+    def unprotect(self) -> None:
+        """Unprotect EEPROM."""
+        self._send(pack('>c', b'u'))
 
     def _rnd(self):
         """returns a generator producing random ASCII data."""
@@ -223,7 +235,10 @@ def repl(self) -> None:
                  'load': self.load,
                  't': self.test,
                  'test': self.test,
-                 'reset': self.reset,
+                 'p': self.protect,
+                 'protect': self.protect,
+                 'u': self.unprotect,
+                 'unprotect': self.unprotect,
                  'quit': self.quit,
                  'q': self.quit}[expr[0]](*expr[1:])
 
@@ -292,4 +307,4 @@ def repl(self) -> None:
             atexit.register(readline.write_history_file, histfile)
             eeprom.repl()
     except (KeyboardInterrupt, BrokenPipeError):
-        eeprom.reset()
+        exit(1)

src/arduino.cpp

@@ -26,7 +26,7 @@
  *  A1 | EEPROM OE
  *  A2 | EEPROM CE
  * ----+--------------
- *  13 | Activity LED
+ *  10 | Activity LED
  * ----+--------------
  *  
  * Copyright 2019, Erik van Zijst <[email protected]>
@@ -55,7 +55,7 @@ typedef enum {
 } error;
 
 const unsigned int MAX_PAYLOAD = 63;
-const unsigned int DELAY_US = 10;
+const unsigned int DELAY_US = 1;
 
 // AT28C256 contol lines
 const unsigned int EEPROM_WE = A0;
@@ -115,6 +115,59 @@ void setup() {
   standbyMode();
 }
 
+void quickWrite(unsigned int addr, byte val) {
+  PORTB &= ~B00001000;
+
+  for (int i = 0; i < 16; ++i) {
+    if (addr & 0x8000) {
+      PORTC |= B00010000;
+    } else {
+      PORTC &= ~B00010000;      
+    }
+    PORTB |= B00001000;
+    delayMicroseconds(3);
+    PORTB &= ~B00001000;
+    addr <<= 1;
+  }
+
+  PORTB = (PORTB & 0xfc) | (val >> 6);
+  PORTD = (PORTD & 0x03) | (val << 2);
+
+  PORTB &= ~B00010000;
+  delayMicroseconds(2);
+  PORTB |= B00010000;
+  delayMicroseconds(2);
+  PORTB &= ~B00010000;
+
+  delayMicroseconds(2);
+  PORTC &= ~B00000001;
+  delayMicroseconds(2);
+  PORTC |= B00000001;
+}
+
+void unprotect() {
+  writeMode();
+
+  quickWrite(0x5555, 0xAA);
+  quickWrite(0x2AAA, 0x55);
+  quickWrite(0x5555, 0x80);
+  quickWrite(0x5555, 0xAA);
+  quickWrite(0x2AAA, 0x55);
+  quickWrite(0x5555, 0x20);
+
+  standbyMode();
+}
+
+void protect() {
+  writeMode();
+
+  quickWrite(0x5555, 0xAA);
+  quickWrite(0x2AAA, 0x55);
+  quickWrite(0x5555, 0xA0);
+
+  standbyMode();
+}
+
 /*
  * Reads the next message from the serial port and copies its payload into
  * the specified `buf` byte array.
@@ -185,12 +238,11 @@ void pulse(int pin) {
  * Loads the specified 16 bit address into the 595 shift register.
  */
 void loadShiftAddr(unsigned int addr) {
+  delayMicroseconds(DELAY_US);
   for (int i = 15; i >= 0; i--) {
     digitalWrite(SHIFT_SER, ((addr >> i) & 1) ? HIGH : LOW);
-    delayMicroseconds(DELAY_US);
     pulse(SHIFT_SCLK);
   }
-  delayMicroseconds(DELAY_US);
   pulse(SHIFT_RCLK);
 }
 
@@ -299,14 +351,14 @@ int load(unsigned int len) {
  * Returns 0 on success, or -1 on error.
  */
 int writeMode() {
-  digitalWrite(EEPROM_CE, LOW);
-  digitalWrite(EEPROM_OE, HIGH);
-  digitalWrite(EEPROM_WE, HIGH);
-
   for (unsigned int i = 0; i < 8; i++) {
     pinMode(dataPins[i], OUTPUT);
   }
 
+  digitalWrite(EEPROM_CE, LOW);
+  digitalWrite(EEPROM_OE, HIGH);
+  digitalWrite(EEPROM_WE, HIGH);
+
   delayMicroseconds(DELAY_US);
   mode = WRITE;
   return 0;
@@ -388,8 +440,11 @@ void loop() {
             send(NULL, 0, false); // acknowledge cmd message
             load((buf[1] << 8) + buf[2]);
 
-        } else if (buf[0] == 0x72 && len == 1) {
-            // ignore reset command
+        } else if (buf[0] == 0x70 && len == 1) {
+            protect();
+
+        } else if (buf[0] == 0x75 && len == 1) {
+            unprotect();
 
         } else {
           errno = E_UNKNOWN;