Add support for SST27C0x0 flash chips

TommyPROM/PromDevice27.cpp

@@ -22,12 +22,13 @@ static void disableWrite()     { digitalWrite(WE, HIGH);}
 
 
 PromDevice27::PromDevice27(uint32_t size, E27C_PGM pgmType, unsigned long pulseWidthUsec,
-                           unsigned writeAttempts, unsigned overwriteMultiplier)
+                           unsigned writeAttempts, unsigned overwriteMultiplier, bool verify)
     : PromDevice(size, 0, 0, false),
       mPgmType(pgmType),
       mPulseWidthUsec(pulseWidthUsec),
       mWriteAttempts(writeAttempts),
-      mOverwriteMultiplier(overwriteMultiplier)
+      mOverwriteMultiplier(overwriteMultiplier),
+      mVerifyByte(verify)
 {
 }
 
@@ -99,14 +100,12 @@ bool PromDevice27::burnByteWE(byte value, uint32_t address)
     bool status = false;
     unsigned writeCount = 0;
 
-    byte data = 0;
     disableOutput();
     disableWrite();
     enableChip();
     setAddress(address);
 
-    while (!status && (writeCount < mWriteAttempts))
+    while (!status && (writeCount < mWriteAttempts)) {
-    {
         setDataBusMode(OUTPUT);
         writeDataBus(value);
         delayMicroseconds(1);
@@ -115,15 +114,17 @@ bool PromDevice27::burnByteWE(byte value, uint32_t address)
         disableWrite();
         ++writeCount;
 
-        setDataBusMode(INPUT);
+        if (mVerifyByte) {
-        enableOutput();
+			setDataBusMode(INPUT);
-        data = readDataBus();
+	        enableOutput();
-        disableOutput();
+	        status = readDataBus() == value;
-        status = (readDataBus() == value);
+	        disableOutput();
+		} else {
+            status = true;
+        }
     }
 
-    if (status && (mOverwriteMultiplier > 0))
+    if (status && (mOverwriteMultiplier > 0)) {
-    {
         setDataBusMode(OUTPUT);
         writeDataBus(value);
         delayMicroseconds(1);
@@ -132,8 +133,8 @@ bool PromDevice27::burnByteWE(byte value, uint32_t address)
         disableWrite();
     }
 
+	setDataBusMode(INPUT);
     disableChip();
-
     return status;
 }
 
@@ -151,14 +152,12 @@ bool PromDevice27::burnByteCE(byte value, uint32_t address)
     bool status = false;
     unsigned writeCount = 0;
 
-    byte data = 0;
     disableOutput();
     disableWrite();
     disableChip();
     setAddress(address);
 
-    while (!status && (writeCount < mWriteAttempts))
+    while (!status && (writeCount < mWriteAttempts)) {
-    {
         setDataBusMode(OUTPUT);
         writeDataBus(value);
         delayMicroseconds(2);
@@ -168,24 +167,24 @@ bool PromDevice27::burnByteCE(byte value, uint32_t address)
         delayMicroseconds(2);
         ++writeCount;
 
-        setDataBusMode(INPUT);
+        if (mVerifyByte) {
-        enableOutput();
+	        setDataBusMode(INPUT);
-        data = readDataBus();
+	        enableOutput();
-        disableOutput();
+	        status = readDataBus() == value;
-        status = (readDataBus() == value);
+	        disableOutput();
+		}
     }
 
+	setDataBusMode(INPUT);
+	disableChip();
     return status;
 }
 
 
 ERET PromDevice27::erase(uint32_t start, uint32_t end)
 {
-    if (mPgmType != E27C_PGM_CE)  return RET_NOT_SUPPORT;
+	ERET status = RET_FAIL;
 
-    // Erase code for the 27E257 and 27C257.  The Vpp and A9 pins are held at 14V for the
-    // erase and verify cycle.  This erases the entire chip, so the start and end address
-    // parameters are ignored.
     disableChip();
     disableOutput();
     setAddress(0);
@@ -193,30 +192,46 @@ ERET PromDevice27::erase(uint32_t start, uint32_t end)
     writeDataBus(0xff);
     delayMicroseconds(2);
 
-    unsigned writeCount = 0;
+    if (mPgmType == E27C_PGM_WE) {
-    ERET status = RET_FAIL;
+		// Erase code for the SST27C0x0.  The Vpp and A9 pins are held at 12V for the
-    while ((status == RET_FAIL) && (writeCount < mWriteAttempts)) {
+		// erase cycle.  This erases the entire chip, so the start and end address
-        setAddress(0);
+		// parameters are ignored.  There is no erase verification for this chip.
-        setDataBusMode(OUTPUT);
+		enableChip();
-        writeDataBus(0xff);
+        delayMicroseconds(1);
-        delayMicroseconds(2);
+		enableWrite();
-        enableChip();
+		delayMicroseconds(100);	// Hard coded for SST27F020
-        delay(100);
+		disableWrite();
-        disableChip();
+		disableChip();
-        delayMicroseconds(2);
+		setDataBusMode(INPUT);
+		status = RET_OK;
+    } else {
+		// Erase code for the 27E257 and 27C257.  The Vpp and A9 pins are held at 14V for
+		// the erase and verify cycle.  This erases the entire chip, so the start and end
+		// address parameters are ignored.
+	    unsigned writeCount = 0;
+	    while ((status == RET_FAIL) && (writeCount < mWriteAttempts)) {
+	        setAddress(0);
+	        setDataBusMode(OUTPUT);
+	        writeDataBus(0xff);
+	        delayMicroseconds(2);
+	        enableChip();
+	        delay(100);
+	        disableChip();
+	        delayMicroseconds(2);
 
-        // Read back the data to verify all cells are erased.  Note That this is done
+	        // Read back the data to verify all cells are erased.  Note That this is done
-        // while CE is HIGH.  This is the erase verify mode.
+	        // while CE is HIGH.  This is the erase verify mode.
-        setDataBusMode(INPUT);
+	        setDataBusMode(INPUT);
-        for (uint32_t address = 0; (address < mSize); address++) {
+	        for (uint32_t address = 0; (address < mSize); address++) {
-            setAddress(address);
+	            setAddress(address);
-            enableOutput();
+	            enableOutput();
-            uint8_t b = readDataBus();
+	            uint8_t b = readDataBus();
-            disableOutput();
+	            disableOutput();
-            if (b != 0xff)  break;
+	            if (b != 0xff)  break;
-        }
+	        }
-        status = RET_OK;
+	        status = RET_OK;
-    }
+	    }
+	}
 
     return status;
 }
@@ -224,15 +239,12 @@ ERET PromDevice27::erase(uint32_t start, uint32_t end)
 
 void PromDevice27::myDelay(unsigned int us)
 {
-    if (us > 16000)
+    if (us > 16000) {
-    {
         // The delayMicroseconds code can't do delays longer than 16ms, so use the
         // ms delay code for larger values.  This rounds down to the nearest ms, so
         // it is not possible to delay for 40.5 ms, for example.
         delay(us / 1000);
-    }
+    } else {
-    else
-    {
         delayMicroseconds((unsigned int) us);
     }
 }

TommyPROM/PromDevice27.h

@@ -36,7 +36,7 @@ class PromDevice27 : public PromDevice
 {
   public:
     PromDevice27(uint32_t size, E27C_PGM pgmType, unsigned long pulseWidthUsec,
-                 unsigned writeAttempts, unsigned overwriteMultiplier);
+                 unsigned writeAttempts, unsigned overwriteMultiplier, bool verify=true);
     void begin();
     const char * getName() { return "27 series EPROM"; }
     ERET erase(uint32_t start, uint32_t end);
@@ -54,6 +54,7 @@ class PromDevice27 : public PromDevice
     unsigned long mPulseWidthUsec;
     unsigned mWriteAttempts;
     unsigned mOverwriteMultiplier;
+    bool     mVerifyByte;
 };
 
 #endif  // #define INCLUDE_PROM_DEVICE_27_H

TommyPROM/PromDevice28C.cpp

@@ -189,7 +189,7 @@ bool PromDevice28C::waitForWriteCycleEnd(byte lastValue)
         byte b1=0, b2=0;
         setDataBusMode(INPUT);
         delayMicroseconds(1);
-        for (int readCount = 1; (readCount < (mMaxWriteTime * 100)); readCount++)
+        for (unsigned readCount = 1; (readCount < (mMaxWriteTime * 100)); readCount++)
         {
             enableChip();
             enableOutput();

TommyPROM/TommyPROM.ino

@@ -19,7 +19,7 @@
 #include "XModem.h"
 
 
-static const char * MY_VERSION = "3.2";
+static const char * MY_VERSION = "3.3";
 
 
 // Global status
@@ -44,11 +44,13 @@ PromDevice28C  prom(32 * 1024L, 64, 10, true);
 //   1000us (1ms) write pulse
 //   15 write attempts
 //   4x overwrite pulse
+//   (true) verify data byte after writing
 //PromDevice27  prom(8 * 1024L, E27C_PGM_WE, 1000L, 15, 4);  // 2764 with SEEQ intelligent programming
 //PromDevice27  prom(32 * 1024L, E27C_PGM_WE, 1000L, 25, 3); // 27C256 with SEEQ intelligent programming
 //PromDevice27  prom(2 * 1024L, E27C_PGM_WE, 50000L, 1, 0);  // 2716 with single 50ms write
-//PromDevice27  prom(64 * 1024L, E27C_PGM_WE, 100L, 11, 0);  // 27C040 with Atmel rapid programming
+//PromDevice27  prom(512 * 1024L, E27C_PGM_WE, 100L, 11, 0); // 27C040 with Atmel rapid programming
-PromDevice27  prom(32 * 1024L, E27C_PGM_CE, 100L, 25, 0); // 27C257/27E257 with 100uS program pulse on CE
+//PromDevice27  prom(32 * 1024L, E27C_PGM_CE, 100L, 25, 0);  // 27C257/27E257 with 100uS program pulse on CE
+PromDevice27  prom(256 * 1024L, E27C_PGM_WE, 20L, 1, 0, false); // SST27SF020 with single 20us write, no verify
 
 #elif defined(PROM_IS_SST39SF)
 // Define a device for anSST39SF Flash with the following parameters:

docs/prom-families.md

@@ -161,7 +161,8 @@ The 8755 build of TommyPROM also has a circuit to control the 25V programming pu
 |:---      |:---         |:---   |:---   |:--- |
 |AT28C256  |Atmel, others|EEPROM |28C    |Fully supported|
 |SST39SF040|Microchip    |Flash  |SST39SF|All SST39SF0x0 supported|
-|SST28SF040|SST          |Flash  |       |All SST28SF0x0 supported|
+|SST28SF040|SST          |Flash  |SST39SF|All SST28SF0x0 supported|
+|SST27SF020|SST          |Flash  |27     |12V continuous for pgm/erase|
 |WE27C257  |Winbond      |EEPROM |27     |Continual 12V or 14V for program/erase|
 |AT29C010  |Atmel        |Flash  |28C    |Only with 128 byte or less sector size|
 |8755A     |Intel        |EPROM  |8755A  |Requires 25V pulses to program|
@@ -195,6 +196,18 @@ This is an earlier version of the SST39SF series chips.  They are pin compatible
 flash chips support software data protection.  The _Lock_ and _Unlock_ commands can be
 used to enable and disable SDP from the command line.
 
+#### SST27SF020
+
+The Silicon Storage SST27SF0x0 are programmed similarly to the 27C257 in that a constant
+voltage is applied for program and erase operations.  Unlike the 27C257, these have a
+dedicated WE pin that controls programming and erasing.  Another difference is that they
+do not have a verify operation to read back the programmed data.
+
+These Flash chips have a _VPP_ pin that needs a constant 12V during programming. Unlike
+the newer 28C EEPROMs, these chips do not automatically erase before writing to a
+location. Instead, the entire chip is erased by applying 12V to _VPP_ and _A9_ and then
+pulsing _WE_.
+
 #### 27C257
 
 The Winbond WE27C257 and WE27E257 appear to be identical 32Kx8 EEPROMs.  The 27C version
@@ -228,4 +241,3 @@ for chips with the 256 byte buffer.
 |Model     |Manufacturer |Type   |Module |Notes|
 |:---      |:---         |:---   |:---   |:--- |
 |M27C4001  |ST Micro     |EEPROM |       |VCC=6.5V, VPP=12.75V to pgm|
-|SST27SF020|SST          |Flash  |       |12V continuous for pgm/erase|