From 8865d0c00fb7770ed86206e170271a224137831b Mon Sep 17 00:00:00 2001
From: Doug Brown <macg3@mac.com>
Date: Sat, 10 Dec 2011 18:40:30 -0800
Subject: [PATCH] I got the device identification working, and I'm in the
 middle of breaking it into its own set of functions for write cycles, read
 cycles, unlock sequence, etc.

---
 .cproject               |  10 +--
 external_mem.c          |  62 ++++++++++++++
 external_mem.h          |  16 ++++
 usb_serial/usb_serial.c | 184 ++++++++++++++++++----------------------
 4 files changed, 164 insertions(+), 108 deletions(-)

diff --git a/.cproject b/.cproject
index 59505e1..d441d93 100644
--- a/.cproject
+++ b/.cproject
@@ -41,9 +41,8 @@
 									<listOptionValue builtIn="false" value="FIXED_NUM_CONFIGURATIONS=1"/>
 									<listOptionValue builtIn="false" value="USE_FLASH_DESCRIPTORS"/>
 									<listOptionValue builtIn="false" value="USE_STATIC_OPTIONS=&quot;(USB_DEVICE_OPT_FULLSPEED | USB_OPT_REG_ENABLED | USB_OPT_AUTO_PLL)&quot;"/>
-									<listOptionValue builtIn="false" value="INTERRUPT_CONTROL_ENDPOINT"/>
 								</option>
-								<option id="de.innot.avreclipse.compiler.option.otherflags.1513967861" superClass="de.innot.avreclipse.compiler.option.otherflags" value="-ffunction-sections -fdata-sections" valueType="string"/>
+								<option id="de.innot.avreclipse.compiler.option.otherflags.1513967861" name="Other flags" superClass="de.innot.avreclipse.compiler.option.otherflags" value="-ffunction-sections -fdata-sections" valueType="string"/>
 								<inputType id="de.innot.avreclipse.compiler.winavr.input.1367172122" name="C Source Files" superClass="de.innot.avreclipse.compiler.winavr.input"/>
 							</tool>
 							<tool id="de.innot.avreclipse.tool.cppcompiler.app.debug.24092953" name="AVR C++ Compiler" superClass="de.innot.avreclipse.tool.cppcompiler.app.debug">
@@ -51,7 +50,7 @@
 								<option id="de.innot.avreclipse.cppcompiler.option.optimize.1022518531" name="Optimization Level" superClass="de.innot.avreclipse.cppcompiler.option.optimize"/>
 							</tool>
 							<tool id="de.innot.avreclipse.tool.linker.winavr.app.debug.806884166" name="AVR C Linker" superClass="de.innot.avreclipse.tool.linker.winavr.app.debug">
-								<option id="de.innot.avreclipse.linker.option.otherlinkargs.1714687929" superClass="de.innot.avreclipse.linker.option.otherlinkargs" value="-Wl,--relax,--gc-sections" valueType="string"/>
+								<option id="de.innot.avreclipse.linker.option.otherlinkargs.1714687929" name="Other Arguments" superClass="de.innot.avreclipse.linker.option.otherlinkargs" value="-Wl,--relax,--gc-sections" valueType="string"/>
 								<inputType id="de.innot.avreclipse.tool.linker.input.1020880987" name="OBJ Files" superClass="de.innot.avreclipse.tool.linker.input">
 									<additionalInput kind="additionalinputdependency" paths="$(USER_OBJS)"/>
 									<additionalInput kind="additionalinput" paths="$(LIBS)"/>
@@ -423,9 +422,8 @@
 									<listOptionValue builtIn="false" value="FIXED_NUM_CONFIGURATIONS=1"/>
 									<listOptionValue builtIn="false" value="USE_FLASH_DESCRIPTORS"/>
 									<listOptionValue builtIn="false" value="USE_STATIC_OPTIONS=&quot;(USB_DEVICE_OPT_FULLSPEED | USB_OPT_REG_ENABLED | USB_OPT_AUTO_PLL)&quot;"/>
-									<listOptionValue builtIn="false" value="INTERRUPT_CONTROL_ENDPOINT"/>
 								</option>
-								<option id="de.innot.avreclipse.compiler.option.otherflags.1566165436" superClass="de.innot.avreclipse.compiler.option.otherflags" value="-ffunction-sections -fdata-sections" valueType="string"/>
+								<option id="de.innot.avreclipse.compiler.option.otherflags.1566165436" name="Other flags" superClass="de.innot.avreclipse.compiler.option.otherflags" value="-ffunction-sections -fdata-sections" valueType="string"/>
 								<inputType id="de.innot.avreclipse.compiler.winavr.input.2084198580" name="C Source Files" superClass="de.innot.avreclipse.compiler.winavr.input"/>
 							</tool>
 							<tool id="de.innot.avreclipse.tool.cppcompiler.app.release.912002244" name="AVR C++ Compiler" superClass="de.innot.avreclipse.tool.cppcompiler.app.release">
@@ -433,7 +431,7 @@
 								<option id="de.innot.avreclipse.cppcompiler.option.optimize.1657124646" name="Optimization Level" superClass="de.innot.avreclipse.cppcompiler.option.optimize" value="de.innot.avreclipse.cppcompiler.optimize.size" valueType="enumerated"/>
 							</tool>
 							<tool id="de.innot.avreclipse.tool.linker.winavr.app.release.381852607" name="AVR C Linker" superClass="de.innot.avreclipse.tool.linker.winavr.app.release">
-								<option id="de.innot.avreclipse.linker.option.otherlinkargs.270243458" superClass="de.innot.avreclipse.linker.option.otherlinkargs" value="-Wl,--relax,--gc-sections" valueType="string"/>
+								<option id="de.innot.avreclipse.linker.option.otherlinkargs.270243458" name="Other Arguments" superClass="de.innot.avreclipse.linker.option.otherlinkargs" value="-Wl,--relax,--gc-sections" valueType="string"/>
 								<inputType id="de.innot.avreclipse.tool.linker.input.567763029" name="OBJ Files" superClass="de.innot.avreclipse.tool.linker.input">
 									<additionalInput kind="additionalinputdependency" paths="$(USER_OBJS)"/>
 									<additionalInput kind="additionalinput" paths="$(LIBS)"/>
diff --git a/external_mem.c b/external_mem.c
index 409dcde..4ca2ccf 100644
--- a/external_mem.c
+++ b/external_mem.c
@@ -8,6 +8,7 @@
 #include "external_mem.h"
 #include "ports.h"
 #include <avr/io.h>
+#include <avr/delay.h>
 
 #define HIGHEST_ADDRESS_LINE	20
 
@@ -124,3 +125,64 @@ void ExternalMem_Read(uint32_t startAddress, uint32_t *buf, uint32_t len)
 		*buf++ = tmp;
 	}
 }
+
+void ExternalMem_WriteCycle(uint32_t address, uint32_t data)
+{
+	ExternalMem_SetAddressAndData(address, data);
+	ExternalMem_AssertWE();
+
+	_delay_us(1); // Give it a small amount of time needed? Could I do this with some NOP instructions instead of waiting 1us?
+	ExternalMem_DeassertWE();
+}
+
+void ExternalMem_UnlockAllChips(void)
+{
+	// Disable the chips completely and wait for a short time...
+	ExternalMem_DeassertCS();
+	ExternalMem_DeassertOE();
+	ExternalMem_DeassertWE();
+	_delay_us(1);
+	ExternalMem_AssertCS();
+
+	// First part of unlock sequence:
+	// Write 0x55555555 to the address bus and 0xAA to the data bus
+	// (Some datasheets may only say 0x555 or 0x5555, but they ignore
+	// the upper bits, so writing the alternating pattern to all address lines
+	// should make it compatible with larger chips)
+	ExternalMem_WriteCycle(0x55555555UL, 0xAAAAAAAAUL);
+
+	// Second part of unlock sequence is the same thing, but reversed.
+	ExternalMem_WriteCycle(0xAAAAAAAAUL, 0x55555555UL);
+}
+
+void ExternalMem_IdentifyChips(struct ChipID *chips)
+{
+	ExternalMem_UnlockAllChips();
+
+	// Write 0x90 to 0x55555555 for the identify command...
+	ExternalMem_WriteCycle(0x55555555UL, 0x90909090UL);
+
+	// Now we can read the vendor and product ID
+	ExternalMem_SetAddress(0);
+	ExternalMem_SetDataAsInput();
+	ExternalMem_AssertOE();
+
+	uint32_t result = ExternalMem_ReadData();
+
+	chips[3].manufacturerID = (uint8_t)result;
+	chips[2].manufacturerID = (uint8_t)(result >> 8);
+	chips[1].manufacturerID = (uint8_t)(result >> 16);
+	chips[0].manufacturerID = (uint8_t)(result >> 24);
+
+	ExternalMem_SetAddress(1);
+	result = ExternalMem_ReadData();
+
+	chips[3].deviceID = (uint8_t)result;
+	chips[2].deviceID = (uint8_t)(result >> 8);
+	chips[1].deviceID = (uint8_t)(result >> 16);
+	chips[0].deviceID = (uint8_t)(result >> 24);
+
+	// Exit software ID mode
+	ExternalMem_DeassertOE();
+	ExternalMem_WriteCycle(0, 0xF0F0F0F0UL);
+}
diff --git a/external_mem.h b/external_mem.h
index 09bcd6a..641b269 100644
--- a/external_mem.h
+++ b/external_mem.h
@@ -11,6 +11,13 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+// Holds info about the chip (retrieved with JEDEC standards)
+struct ChipID
+{
+	uint8_t manufacturerID;
+	uint8_t deviceID;
+};
+
 // Initializes the (bit-banged) external memory interface
 void ExternalMem_Init(void);
 
@@ -44,4 +51,13 @@ void ExternalMem_DeassertOE(void);
 // Reads a set of data...
 void ExternalMem_Read(uint32_t startAddress, uint32_t *buf, uint32_t len);
 
+// Performs a write cycle
+void ExternalMem_WriteCycle(uint32_t address, uint32_t data);
+
+// Does an unlock sequence on the chips
+void ExternalMem_UnlockAllChips(void);
+
+// Identifies the chips that are currently in the SIMM
+void ExternalMem_IdentifyChips(struct ChipID *chips);
+
 #endif /* EXTERNAL_MEM_H_ */
diff --git a/usb_serial/usb_serial.c b/usb_serial/usb_serial.c
index 3eb3e1b..056fab1 100644
--- a/usb_serial/usb_serial.c
+++ b/usb_serial/usb_serial.c
@@ -43,30 +43,8 @@ void USBSerial_Check(void)
 		if (CDC_Device_BytesReceived(&VirtualSerial_CDC_Interface))
 		{
 			CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
-			//CDC_Device_SendString(&VirtualSerial_CDC_Interface, "Reading...");
-			//CDC_Device_Flush(&VirtualSerial_CDC_Interface);
 
-			/*uint32_t mem = ExternalMem_ReadData();
-
-			char dataString[11];
-
-			sprintf(dataString, "%08lX\r\n", mem);
-
-			CDC_Device_SendString(&VirtualSerial_CDC_Interface, dataString);
-
-			sprintf(dataString, "%02X%02X%02X%02X\r\n",
-					(uint8_t)(mem>>24),
-					(uint8_t)(mem>>16),
-					(uint8_t)(mem>>8),
-					(uint8_t)(mem>>0));
-
-			CDC_Device_SendString(&VirtualSerial_CDC_Interface, dataString);
-
-			sprintf(dataString, "%02X %02X %02X\r\n", DDRA, DDRC, DDRD);
-
-			CDC_Device_SendString(&VirtualSerial_CDC_Interface, dataString);*/
-
-#define BUFSIZE 128UL
+			/*#define BUFSIZE 128UL
 			static uint32_t readBuf[BUFSIZE];
 			int x;
 			for (x = 0; x < 512UL * 1024UL / BUFSIZE; x++)
@@ -77,86 +55,88 @@ void USBSerial_Check(void)
 				{
 					PORTD |= (1 << 7);
 				}
-
-				//int y;
-				//for (y = 0; y < BUFSIZE; y++)
-				//{
-					//if ((y % 4) == 0) CDC_Device_SendString(&VirtualSerial_CDC_Interface, ".\r\n");
-
-					//char tmpBuf[20];
-					//sprintf(tmpBuf, "%02X %02X %02X %02X ",
-					//		(uint8_t)(readBuf[y] >> 24),
-					//		(uint8_t)(readBuf[y] >> 16),
-					//		(uint8_t)(readBuf[y] >> 8),
-					//		(uint8_t)(readBuf[y] >> 0));
-					//CDC_Device_SendString(&VirtualSerial_CDC_Interface, tmpBuf);
-				//}
-				//if ((x % 64) == 0) CDC_Device_SendString(&VirtualSerial_CDC_Interface, "\r\n");
-				//CDC_Device_SendString(&VirtualSerial_CDC_Interface, ".");
-				//CDC_Device_Flush(&VirtualSerial_CDC_Interface);
-			}
-
-			//CDC_Device_SendString(&VirtualSerial_CDC_Interface, "\r\nDone\r\n");
-		}
-
-		/*int16_t rb = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
-		if (rb >= 0)
-		{
-			if (rb == '.')
-			{
-				gotChar = 0;
-			}
-			else
-			{
-				gotChar = 1;
-			}
-		}
-
-		if (gotChar)
-		{*/
-			//if (CDC_Device_SendByte(&VirtualSerial_CDC_Interface, 'A') != ENDPOINT_READYWAIT_NoError)
-			/*if (CDC_Device_SendData(&VirtualSerial_CDC_Interface,
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					"ASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDFASDF"
-					, 2048) != ENDPOINT_RWSTREAM_NoError)
-			{
-				PORTD |= (1 << 7);
-			}
-			else
-			{
-				PORTD &= ~(1 << 7);
 			}*/
-		//}
+
+			// Start out in programming state...
+			ExternalMem_DeassertCS();
+			ExternalMem_DeassertOE();
+			ExternalMem_DeassertWE();
+			_delay_us(1);
+
+			// Write 0xAA to 0x555 (first byte of unlock sequence)
+			// (The SST39SF040 asks for 0x5555 here -- but it doesn't matter, it's
+			// just an alternating pattern of 1s and 0s and the chips will ignore
+			// the bits above the value it asks for -- so I can just write a huge
+			// alternating pattern and it will work with most/all chips)
+			ExternalMem_SetAddressAndData(0x55555555UL, 0xAAAAAAAAUL);
+			ExternalMem_AssertCS();
+			ExternalMem_AssertWE();
+			_delay_us(1);
+			ExternalMem_DeassertWE();
+			_delay_us(1);
+
+			// Write 0x55 to 0x2AA (second byte of unlock sequence)
+			ExternalMem_SetAddressAndData(0xAAAAAAAAUL, 0x55555555UL);
+			ExternalMem_AssertWE();
+			_delay_us(1);
+			ExternalMem_DeassertWE();
+			_delay_us(1);
+
+			// Write 0x90 to 0x555 (autoselect command)
+			ExternalMem_SetAddressAndData(0x55555555UL, 0x90909090UL);
+			ExternalMem_AssertWE();
+			_delay_us(1);
+			ExternalMem_DeassertWE();
+			//ExternalMem_DeassertCS();
+			_delay_us(1);
+
+			// Now we can start reading...
+			ExternalMem_SetAddress(0x0);
+			ExternalMem_SetDataAsInput();
+			ExternalMem_AssertOE();
+			//ExternalMem_AssertCS();
+
+			_delay_us(1);
+
+			uint32_t result = ExternalMem_ReadData();
+
+			char test[20];
+			sprintf(test, "%08lX ", result);
+			CDC_Device_SendString(&VirtualSerial_CDC_Interface, test);
+
+			ExternalMem_SetAddress(0x1);
+			result = ExternalMem_ReadData();
+			sprintf(test, "%08lX\r\n", result);
+			CDC_Device_SendString(&VirtualSerial_CDC_Interface, test);
+
+			// Exit back to normal mode...
+			ExternalMem_DeassertOE();
+			ExternalMem_SetAddressAndData(0x0, 0xF0F0F0F0UL);
+			//ExternalMem_AssertCS();
+			ExternalMem_AssertWE();
+			_delay_us(1);
+			ExternalMem_DeassertWE();
+			//ExternalMem_DeassertCS();
+			_delay_us(1);
+
+			// Now do normal read cycle to confirm we exited
+			ExternalMem_SetAddress(0x0);
+			ExternalMem_SetDataAsInput();
+			ExternalMem_AssertOE();
+			//ExternalMem_AssertCS();
+
+			_delay_us(1);
+
+			result = ExternalMem_ReadData();
+
+			sprintf(test, "%08lX ", result);
+			CDC_Device_SendString(&VirtualSerial_CDC_Interface, test);
+
+			ExternalMem_SetAddress(0x1);
+			result = ExternalMem_ReadData();
+			sprintf(test, "%08lX\r\n", result);
+			CDC_Device_SendString(&VirtualSerial_CDC_Interface, test);
+		}
 	}
 
 	CDC_Device_USBTask(&VirtualSerial_CDC_Interface);