# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1439140095 -7200
# Node ID deaef57647e7da71a0764668193ed49bc1519d6e
# Parent  dcd08661531d719417358650109c9b3bfa6202eb
Added support for controlling A16 when programming. Fixed the read examples.

diff -r dcd08661531d -r deaef57647e7 ArduinoAm29F010.cpp
--- a/ArduinoAm29F010.cpp	Sun Aug 09 01:10:40 2015 +0200
+++ b/ArduinoAm29F010.cpp	Sun Aug 09 19:08:15 2015 +0200
@@ -16,7 +16,7 @@
 with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-const int CE = A5, OE = A4, WE = A3,
+const int CE = A5, OE = A4, WE = A3, A16 = A2,
           CS1 = 2, CS2 = 3,
           DQ0 = 7, DQ1 = 6, DQ2 = 5, DQ3 = 4,
           DQ4 = 8, DQ5 = 9, DQ6 = 10, DQ7 = 11;
@@ -111,6 +111,15 @@
 
 void setAddress(int high, int low)
 {
+    /* The top bit is sent directly. */
+
+    if (high & 0x100)
+        digitalWrite(A16, HIGH);
+    else
+        digitalWrite(A16, LOW);
+
+    /* The lower 16 bits are sent via the latches. */
+
     writeData(high);
     delayMicroseconds(1);
     digitalWrite(CS2, HIGH);
@@ -153,21 +162,37 @@
 
 int readCommand(const char buffer[])
 {
-    int high, low;
+    int high, low, i;
 
-    high = (fromHex(buffer[1]) << 4) + (fromHex(buffer[2]));
-    low = (fromHex(buffer[3]) << 4) + (fromHex(buffer[4]));
+    if (nread > 5)
+    {
+        high = fromHex(buffer[1]) << 8;
+        i = 2;
+    }
+    else
+        i = 1;
+
+    high |= (fromHex(buffer[i]) << 4) + (fromHex(buffer[i+1]));
+    low = (fromHex(buffer[i+2]) << 4) + (fromHex(buffer[i+3]));
 
     return readOp(high, low);
 }
 
 bool writeCommand(const char buffer[])
 {
-    int high, low, data;
+    int high, low, data, i;
 
-    high = (fromHex(buffer[1]) << 4) + (fromHex(buffer[2]));
-    low = (fromHex(buffer[3]) << 4) + (fromHex(buffer[4]));
-    data = (fromHex(buffer[5]) << 4) + (fromHex(buffer[6]));
+    if (nread > 7)
+    {
+        high = fromHex(buffer[1]) << 8;
+        i = 2;
+    }
+    else
+        i = 1;
+
+    high |= (fromHex(buffer[i]) << 4) + (fromHex(buffer[i+1]));
+    low = (fromHex(buffer[i+2]) << 4) + (fromHex(buffer[i+3]));
+    data = (fromHex(buffer[i+4]) << 4) + (fromHex(buffer[i+5]));
 
     writeOp(high, low, data);
 
@@ -252,6 +277,7 @@
     pinMode(CE, OUTPUT);
     pinMode(OE, OUTPUT);
     pinMode(WE, OUTPUT);
+    pinMode(A16, OUTPUT);
     pinMode(CS1, OUTPUT);
     pinMode(CS2, OUTPUT);
     setDataOut();
@@ -261,6 +287,7 @@
     digitalWrite(CE, HIGH);
     digitalWrite(OE, HIGH);
     digitalWrite(WE, HIGH);
+    digitalWrite(A16, LOW);
 
     // Initial state for the latches.
 
diff -r dcd08661531d -r deaef57647e7 README.txt
--- a/README.txt	Sun Aug 09 01:10:40 2015 +0200
+++ b/README.txt	Sun Aug 09 19:08:15 2015 +0200
@@ -42,8 +42,13 @@
 
 Issuing read commands permits the testing of addresses in the device:
 
-R0000 (reads from the first location, 0x0000, residing in sector 0)
-R7fff (reads from the final location, 0x7fff, residing in sector 3)
+        location    sector
+R0000   0x0000      0       (the first location in the device)
+R00000  0x0000      0       (all 17 address bits indicated)
+R7fff   0x7fff      1       (the final location in sector 1)
+R07fff  0x7fff      1       (all 17 address bits indicated)
+R10000  0x10000     4       (the first location in sector 4)
+R1ffff  0x1ffff     7       (the final location in the device)
 
 Uploading and Testing Images
 ----------------------------
@@ -78,11 +83,12 @@
 -----------------
 
 Each sector is 16 kilobytes long, which corresponds to a 14-bit address range
-(0x0000 to 0x3FFF). The Arduino interface described below supports 16-bit
-addressing (A0...A15), permitting access to four sectors (at 0x0000, 0x4000,
-0x8000 and 0xC000), leaving A16 grounded and thus not accessing the upper four
-sectors in the device. However, A16 could be connected to VCC to access the
-upper four sectors.
+(0x0000 to 0x3FFF). The Arduino interface described below supports 17-bit
+addressing (A0...A16), permitting access to eight sectors (at 0x0000, 0x4000,
+0x8000, 0xC000, 0x10000, 0x14000, 0x18000 and 0x1C000). The simple mapping from
+a ROM cartridge to the device leaves A16 grounded and thus unable to access the
+upper four sectors in the device. However, A16 could be connected to VCC to
+access the upper four sectors.
 
 Device Compatibility
 ====================
@@ -209,18 +215,18 @@
 Arduino Interfacing
 ===================
 
-Arduino can employ at most 14 digital pins, whereas the Am29F010B requires 17
-address pins, 8 data pins, plus 3 control pins to be utilised.
+Arduino can employ at most 14 digital pins (plus 5 switchable analogue pins),
+whereas the Am29F010B requires 17 address pins, 8 data pins, plus 3 control
+pins to be utilised.
 
 One solution is to map the 3 control pins directly to the Arduino, then to
-channel address and data via 8 common pins to latches, and then employ the
-remaining pins to control the latches.
+channel address and data via 8 common pins to latches, and then employ two
+remaining pins to control the latches. When neither latch is selected, the
+data pins will be used to read or write data from the flash memory.
 
-Two pins can be used to select the latches, and when neither latch is
-selected, the data pins will be used to read or write data from the flash
-memory.
-
-As a result, only 13 pins are needed on the Arduino.
+In this scheme, A16 must be directly controlled by an additional pin, separate
+from the latch-based mechanism. As a result, only 14 pins are needed on the
+Arduino.
 
 74HC273 Pinout
 --------------
@@ -267,7 +273,7 @@
                         Q5          A13
                         Q6          A14
                         Q7          A15
-GND                                 A16 (not used)
+A2                                  A16
 5V          MR#         MR#
 5V          VCC         VCC         VCC
 GND         GND         GND         VSS
@@ -279,6 +285,7 @@
 74HC273 #1 D[7...0] = A[7...0]
 74HC273 #1 CP = 0; 74HC273 #2 CP = 1
 74HC273 #2 D[7...0] = A[15...8]
+Am29F010 A16 = A[16]
 
 Write Data
 ----------