1 The Am29F010-90PC product has been used to test the software and hardware
2 design described here.
3
4 Using the Software
5 ==================
6
7 First of all, to use the Arduino-based programming solution, the Arduino needs
8 to have a program transferred to it. The program is compiled using the
9 Makefile provided, using the simple command...
10
11 make
12
13 To upload the program, the "upload" target is used as follows:
14
15 make upload
16
17 It is likely that this will fail unless appropriate permissions are available
18 on the device through which the Arduino is accessed on the host machine. Thus,
19 a privileged invocation is likely to be necessary:
20
21 sudo make upload
22
23 With the program uploaded, it should now be possible to communicate with the
24 Arduino. Unless the programming circuit has been constructed, however, there
25 will not be any effect of communicating with the Arduino, other than to check
26 that the program is operational. Running the upload.py script as follows will
27 permit such a test:
28
29 ./upload.py -i
30
31 Again, it is likely that this will need to be run in a privileged fashion as
32 follows:
33
34 sudo ./upload.py -i
35
36 The script should act as a terminal, showing a ">" prompt that can accept
37 various commands. Merely getting the prompt should be enough of an indication
38 that the program is functioning on the device.
39
40 Once the programming circuit has been constructed (see "Arduino Interfacing"
41 below), the upload.py script can be used to upload data to the Am29F010
42 device. For example:
43
44 sudo ./upload.py jungle.rom
45
46 This will take jungle.rom and write it to the first sector of the Am29F010. To
47 verify the operation, the following command can be used:
48
49 sudo ./upload.py -v jungle.rom
50
51 To write to other sectors, an option can be specified. For example:
52
53 sudo ./upload.py -s 1 junglecode.rom
54
55 Again, the operation can be verified as follows:
56
57 sudo ./upload.py -s 1 -v junglecode.rom
58
59 Note that the -s option must appear first.
60
61 The upload.py script can accept multiple files and will write each of them to
62 consecutive sectors. However, it can be more prudent to write files
63 individually, especially if the circuit is behaving in a less than completely
64 reliable fashion.
65
66 Device Compatibility
67 ====================
68
69 For use with an Acorn Electron ROM cartridge or other board providing a ROM
70 socket, the compatibility of the Am29F010 needs to be assessed in the context
71 of the ROM sockets likely to be provided.
72
73 Original ROM Pinout Am29F010 Pinout
74 ------------------- ---------------
75
76 1 \/ 32 VCC
77 A16 2 31 WE#
78 1 \/ 28 VCC A15 3 30
79 A12 2 27 A14 A12 4 29 A14
80 A7 3 26 A13 A7 5 28 A13
81 A6 4 25 A8 A6 6 27 A8
82 A5 5 24 A9 A5 7 26 A9
83 A4 6 23 A11 A4 8 25 A11
84 A3 7 22 OE# A3 9 24 OE#
85 A2 8 21 A10 A2 10 23 A10
86 A1 9 20 CS# A1 11 22 CE#
87 A0 10 19 D7 A0 12 21 DQ7
88 D0 11 18 D6 DQ0 13 20 DQ6
89 D1 12 17 D5 DQ1 14 19 DQ5
90 D2 13 16 D4 DQ2 15 18 DQ4
91 GND 14 15 D3 GND/VSS 16 17 DQ3
92
93 Superimposing the Am29F010 onto a ROM socket would provide compatibility for
94 all pins from A12 to GND/VSS and from A14 to D3/DQ3.
95
96 Pin 1 in a ROM socket would correspond to A15 but is not necessarily
97 connected, nor, perhaps, is A14 since only 14 bits are required to address 16
98 kilobytes, although there may be 32 kilobyte sockets connecting A14 and using
99 15 bits to address 32K. A16 and A15 would probably be connected to ground to
100 ensure correct operation, but could also be wired to a selection mechanism so
101 that the entire contents of the flash memory might be exposed.
102
103 Pin 28 is a ROM socket would provide power, but the corresponding pin 30 on an
104 Am29F010 is not connected. Thus pin 30 would need routing to pin 32 for the
105 flash device socket.
106
107 Pin 31 for the Am29F010 would need to be asserted. Thus pin 30 might also be
108 routed to pin 31, so that the device would remain read-only at all times.
109
110 Dual ROM Adapter Usage
111 ======================
112
113 A single Am29F010 device could be wired to two ROM sockets in order to provide
114 data to both. The above wiring guide would be employed, with connections from
115 both sockets being connected to the Am29F010, but additional logic would be
116 required for the CS# signals originating from the sockets in order to expose
117 the appropriate region of flash memory. ROM #1 would be served by a "lower"
118 16K region; ROM #2 would be served by an "upper" 16K region; A14 would be used
119 to switch between these regions.
120
121 When ROM #1's CS# signal is low, an attempt to read from ROM #1 would be
122 occurring, and thus A14 would be held low. And when ROM #2's CS# signal is
123 low, an attempt to read from ROM #2 would be occurring, and thus A14 would be
124 held high.
125
126 Meanwhile, the CS# signal for the two ROM sockets would need to be combined to
127 produce a resultant CE# signal for the Am29F010.
128
129 ROM #1 CS# ROM #2 CS# Am29F010 A14 Am29F010 CE#
130 ---------- ---------- ------------ ------------
131 0 0 Not defined Not defined
132 0 1 0 0
133 1 0 1 0
134 1 1 Not defined 1
135
136 It might therefore be possible to connect A14 to ROM #1's CS# signal. And the
137 resultant CE# signal could be the product of an AND gate:
138
139 Am29F010 CE# = ROM #1 CS# AND ROM #2 CS#
140
141 Wiring Details
142 --------------
143
144 ROM #1 ROM #2 74HC08 Am29F010
145 ------ ------ ------ --------
146 CS# 1A A14
147 CS# 1B
148 1Y CE#
149 OE# OE#
150
151 ROM (Common) 74HC08 Am29F010
152 ------------ ------ --------
153 VCC VCC
154 GND GND
155 VCC VCC
156 VCC WE#
157 D0 DQ0
158 D1 DQ1
159 D2 DQ2
160 D3 DQ3
161 D4 DQ4
162 D5 DQ5
163 D6 DQ6
164 D7 DQ7
165 A0 A0
166 A1 A1
167 A2 A2
168 A3 A3
169 A4 A4
170 A5 A5
171 A6 A6
172 A7 A7
173 A8 A8
174 A9 A9
175 A10 A10
176 A11 A11
177 A12 A12
178 A13 A13
179 GND A15
180 GND A16
181 GND GND
182
183 Arduino Interfacing
184 ===================
185
186 Arduino can employ at most 14 digital pins, whereas the Am29F010B requires 17
187 address pins, 8 data pins, plus 3 control pins to be utilised.
188
189 One solution is to map the 3 control pins directly to the Arduino, then to
190 channel address and data via 8 common pins to latches, and then employ the
191 remaining pins to control the latches.
192
193 Two pins can be used to select the latches, and when neither latch is
194 selected, the data pins will be used to read or write data from the flash
195 memory.
196
197 As a result, only 13 pins are needed on the Arduino.
198
199 74HC273 Pinout
200 --------------
201
202 MR# 1 \/ 20 VCC
203 Q0 2 19 Q7
204 D0 3 18 D7
205 D1 4 17 D6
206 Q1 5 16 Q6
207 Q2 6 15 Q5
208 D2 7 14 D5
209 D3 8 13 D4
210 Q3 9 12 Q4
211 GND 10 11 CP
212
213 Arduino 74HC273 #1 74HC273 #2 Am29F010
214 ------- ---------- ---------- --------
215 A5 CE#
216 A4 OE#
217 A3 WE#
218 2 CP
219 3 CP
220 4 D0 D0 DQ0
221 5 D1 D1 DQ1
222 6 D2 D2 DQ2
223 7 D3 D3 DQ3
224 8 D4 D4 DQ4
225 9 D5 D5 DQ5
226 10 D6 D6 DQ6
227 11 D7 D7 DQ7
228 Q0 A0
229 Q1 A1
230 Q2 A2
231 Q3 A3
232 Q4 A4
233 Q5 A5
234 Q6 A6
235 Q7 A7
236 Q0 A8
237 Q1 A9
238 Q2 A10
239 Q3 A11
240 Q4 A12
241 Q5 A13
242 Q6 A14
243 Q7 A15
244 GND A16 (not used)
245 5V MR# MR#
246 5V VCC VCC VCC
247 GND GND GND VSS
248
249 Set Address
250 -----------
251
252 74HC273 #1 CP = 1; 74HC273 #2 CP = 0
253 74HC273 #1 D[7...0] = A[7...0]
254 74HC273 #1 CP = 0; 74HC273 #2 CP = 1
255 74HC273 #2 D[7...0] = A[15...8]
256
257 Write Data
258 ----------
259
260 Configure pins as D[7...0]
261 WE# = 0
262 74HC273 #1 CP = 0; 74HC273 #2 CP = 0
263 74HC273 #3 D[7...0] = D[7...0]
264 WE# = 1
265
266 Read Data
267 ---------
268
269 Configure pins as Q[7...0]
270 OE# = 0
271 74HC273 #1 CP = 1; 74HC273 #2 CP = 0
272 Q[7...0] = 74HC273 #0 Q[7...0]
273 OE# = 1
274
275 Pins
276 ====
277
278 A0-A16 17-bit addressing
279 DQ0-DQ7 8-bit data transfer
280 CE# chip enable
281 OE# output enable
282 WE# write enable
283 VCC 5V
284 VSS ground
285 NC (not connected)
286
287 Low-Level Operations
288 ====================
289
290 CE# high standby
291 CE# low read, write or output disable
292
293 OE# high, WE# high output disable
294 OE# low, WE# high read
295 OE# high, WE# low write
296
297 Thus, for reading and writing:
298
299 OE# = not WE#
300
301 Timing
302 ======
303
304 According to the datasheet, addresses are latched on the falling edge of the
305 latest of WE# and CE#, data is latched on the rising edge of the latest of WE#
306 and CE#.
307
308 Strategy:
309
310 1. Start with CE#, OE#, WE# high (standby, output disable)
311 2. Bring CE# low (output disable)
312 3. Set addresses
313 4. Bring WE# or OE# low for operation (write or read)
314 5. Read or write data
315 6. Bring WE# or OE# high (output disable)
316
317 Operation Modes
318 ===============
319
320 By default, the device is in read mode, meaning that merely bringing OE# low
321 will produce data for the asserted address.
322
323 To issue commands to change the mode involves write operations with specific
324 address and data arguments.
325
326 Sectors
327 =======
328
329 A[16...14] selects each 16KB sector and is referred to as the sector address
330 or SA in the documentation.
331
332 Commands
333 ========
334
335 Reset (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=$5555; D=$F0)
336
337 Autoselect (manufacturer) (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=$5555; D=$90);
338 (A=$X00; read)
339 => D=$01
340
341 Autoselect (device) (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=$5555; D=$90);
342 (A=$X01; read)
343 => D=$20
344
345 Simple reset (A=$XXXX; D=$F0)
346
347 Sector erase (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=$5555; D=$80);
348 (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=SA; D=$30)
349
350 Program (A=$5555; D=$AA); (A=$2AAA; D=$55); (A=$5555; D=$A0);
351 (A=PA; D=PD)
352
353 Progress
354 --------
355
356 Programming and erasure commands employ data pins as follows:
357
358 Programming Erasure
359 DQ7 On completion: DQ7-out On completion: 1
360 DQ6 During: toggling value During: toggling value
361 DQ5 On failure: 1 On failure: 1
362 DQ3 Sector erase begun: 1
363
364 A read operation is required to obtain these outputs, typically with the same
365 address used to initiate each operation.
