Automatic detection of 2316 chip selects

TommyPROM/PromDevice.cpp

@@ -114,6 +114,8 @@ void PromDevice::setDataBusMode(uint8_t mode)
     {
         DDRB &= 0xfc;
         DDRD &= 0x03;
+        PORTB |= 0x03;  // set pullup resistors
+        PORTD |= 0xfc;
     }
 }
 

TommyPROM/PromDevice23.cpp

@@ -8,17 +8,25 @@
 
 // IO lines for the EPROM device control
 // Pins D2..D9 are used for the data bus.
-#define CS3              A0
+#define CS3_PIN          A0
-#define CS1              A1
+#define CS2_PIN          A1
-#define CS2              A2
+#define CS1_PIN          A2
+#define CS3_BIT          0x04
+#define CS2_BIT          0x02
+#define CS1_BIT          0x01
+
+static unsigned csBits;
 
 // Set the status of the device control pins
-static void enableCS1()     { digitalWrite(CS1, HIGH); }
+static void enableCS(unsigned pin,  unsigned maskBit) { digitalWrite(pin, (csBits & maskBit) ? HIGH : LOW); }
-static void disableCS1()    { digitalWrite(CS1, LOW);}
+static void disableCS(unsigned pin, unsigned maskBit) { digitalWrite(pin, (csBits & maskBit) ? LOW : HIGH); }
-static void enableCS2()     { digitalWrite(CS2, HIGH); }
+
-static void disableCS2()    { digitalWrite(CS2, LOW);}
+static void enableCS1()     { enableCS(CS1_PIN,  CS1_BIT); }
-static void enableCS3()     { digitalWrite(CS3, HIGH); }
+static void disableCS1()    { disableCS(CS1_PIN, CS1_BIT); }
-static void disableCS3()    { digitalWrite(CS3, LOW);}
+static void enableCS2()     { enableCS(CS2_PIN,  CS2_BIT); }
+static void disableCS2()    { disableCS(CS2_PIN, CS2_BIT); }
+static void enableCS3()     { enableCS(CS3_PIN,  CS3_BIT); }
+static void disableCS3()    { disableCS(CS3_PIN, CS3_BIT); }
 
 
 PromDevice23::PromDevice23(uint32_t size)
@@ -31,11 +39,12 @@ void PromDevice23::begin()
 {
     // Define the data bus as input initially so that it does not put out a
     // signal that could collide with output on the data pins of the EEPROM.
-    setDataBusMode(INPUT);
+    setDataBusMode(INPUT_PULLUP);
 
-    pinMode(CS1, OUTPUT);
+    csBits = 0;  // Init to CS3, CS2, and CS1 all active LOW
-    pinMode(CS2, OUTPUT);
+    pinMode(CS1_PIN, OUTPUT);
-    pinMode(CS3, OUTPUT);
+    pinMode(CS2_PIN, OUTPUT);
+    pinMode(CS3_PIN, OUTPUT);
     
     disableCS1();
     disableCS2();
@@ -46,9 +55,106 @@ void PromDevice23::begin()
 }
 
 
+// Override the existing Unlock command to scan the different combinations of CS until
+// data is found.  If the CS lines are not correctly configured, the chip should not
+// assert any signals on the data bus and the Arduino will read back all FF.
+ERET PromDevice23::disableSoftwareWriteProtect()
+{
+    // Finish out the Unlock message printed by the UI code
+    Serial.println("just kidding!");
+
+    // Scan a few different addresses in case there are legitimate empty blocks.  With
+    // the total ROM size of 2K, it is very unlikely that there are several unused
+    // 16-byte blocks, so a valid set of CS pins should encounter some data.
+    for (uint32_t addrBase = 0x0000; (addrBase < mSize); addrBase += 0x250)
+    {
+        if (scanAddress(addrBase))
+        {
+            Serial.print("Setting CS bits to ");
+            printCSbits(csBits);
+            Serial.println();
+            return RET_OK;
+        }
+    }
+
+    Serial.println("No valid CS settings found");
+
+    return RET_FAIL;
+}
+
+
 // BEGIN PRIVATE METHODS
 //
 
+// Print the current CS bit settings.
+void PromDevice23::printCSbits(unsigned bits)
+{
+        Serial.print("CS3:");
+        Serial.print((bits & CS3_BIT) ? 'H':'L');
+        Serial.print("  CS2:");
+        Serial.print((bits & CS2_BIT) ? 'H':'L');
+        Serial.print("  CS1:");
+        Serial.print((bits & CS1_BIT) ? 'H':'L');
+}
+
+
+// Try all combinations of the CS bits and read 16 bytes of data from the chip.
+// One of the CS settings should read some non-FF data.
+bool PromDevice23::scanAddress(uint32_t addrBase)
+{
+    unsigned saveBits = 0xff;
+
+    Serial.print("\nScanning Chip Select combinations starting at address ");
+    printByte(addrBase >> 8);
+    printByte(addrBase & 0xff);
+    Serial.println();
+
+    for (csBits = 0; (csBits < 8); csBits++)
+    {
+        // Disable all CS bits using the new definition of csBits
+        disableCS3();
+        disableCS2();
+        disableCS1();
+
+        printCSbits(csBits);
+        Serial.print(" - ");
+        for (unsigned offset = 0; (offset < 16); offset++)
+        {
+            byte data = readByte(addrBase + offset);
+            printByte(data);
+            Serial.print(' ');
+            if (data != 0xff)
+            {
+                // this combination of Chip Selects successfully read data
+                saveBits = csBits;
+            }
+        }
+        Serial.println();
+    }
+
+    if (saveBits != 0xff)
+    {
+        csBits = saveBits;
+        return true;
+    }
+    return false;
+}
+
+
+static const char hex[] = "0123456789abcdef";
+
+void PromDevice23::printByte(byte b)
+{
+    char line[3];
+
+    line[0] = hex[b >> 4];
+    line[1] = hex[b & 0x0f];
+    line[2] = '\0';
+
+    Serial.print(line);
+}
+
+
 // Use the PromAddressDriver to set a 16 bit address in the two address shift registers.
 void PromDevice23::setAddress(uint32_t address)
 {
@@ -61,7 +167,7 @@ byte PromDevice23::readByte(uint32_t address)
 {
     byte data = 0;
     setAddress(address);
-    setDataBusMode(INPUT);
+    setDataBusMode(INPUT_PULLUP);
     enableCS1();
     enableCS2();
     enableCS3();

TommyPROM/PromDevice23.h

@@ -24,8 +24,12 @@ class PromDevice23 : public PromDevice
     PromDevice23(uint32_t size);
     void begin();
     const char *getName() { return "23 series PROM"; }
+    ERET disableSoftwareWriteProtect();  // use the Unlock command to scan the chip selects
 
   protected:
+    void printCSbits(unsigned bits);
+    bool scanAddress(uint32_t addrBase);
+    void printByte(byte b);
     void setAddress(uint32_t address);
     byte readByte(uint32_t address);
     bool burnByte(byte value, uint32_t address) { return false; }

TommyPROM/TommyPROM.ino

@@ -19,7 +19,7 @@
 #include "XModem.h"
 
 
-static const char * MY_VERSION = "3.3";
+static const char * MY_VERSION = "3.4";
 
 
 // Global status
@@ -74,7 +74,7 @@ PromDeviceSST28SF  prom(512 * 1024L, 40, true);
 PromDevice8755A  prom(2 * 1024L);
 
 #elif defined(PROM_IS_23)
-PromDevice23 prom(2 * 1024L);	// 2316
+PromDevice23 prom(2 * 1024L);   // 2316
 
 // Additional device-specific code goes here...
 //#elif defined(PROM_IS...