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2 spi_butterfly - parport-to-butterfly adapter d 2 spi_butterfly - parport-to-butterfly adapter driver
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4 4
5 This is a hardware and software project that i 5 This is a hardware and software project that includes building and using
6 a parallel port adapter cable, together with a 6 a parallel port adapter cable, together with an "AVR Butterfly" to run
7 firmware for user interfacing and/or sensors. 7 firmware for user interfacing and/or sensors. A Butterfly is a $US20
8 battery powered card with an AVR microcontroll 8 battery powered card with an AVR microcontroller and lots of goodies:
9 sensors, LCD, flash, toggle stick, and more. 9 sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to
10 develop firmware for this, and flash it using 10 develop firmware for this, and flash it using this adapter cable.
11 11
12 You can make this adapter from an old printer 12 You can make this adapter from an old printer cable and solder things
13 directly to the Butterfly. Or (if you have th 13 directly to the Butterfly. Or (if you have the parts and skills) you
14 can come up with something fancier, providing 14 can come up with something fancier, providing circuit protection to the
15 Butterfly and the printer port, or with a bett 15 Butterfly and the printer port, or with a better power supply than two
16 signal pins from the printer port. Or for tha 16 signal pins from the printer port. Or for that matter, you can use
17 similar cables to talk to many AVR boards, eve 17 similar cables to talk to many AVR boards, even a breadboard.
18 18
19 This is more powerful than "ISP programming" c 19 This is more powerful than "ISP programming" cables since it lets kernel
20 SPI protocol drivers interact with the AVR, an 20 SPI protocol drivers interact with the AVR, and could even let the AVR
21 issue interrupts to them. Later, your protoco 21 issue interrupts to them. Later, your protocol driver should work
22 easily with a "real SPI controller", instead o 22 easily with a "real SPI controller", instead of this bitbanger.
23 23
24 24
25 The first cable connections will hook Linux up 25 The first cable connections will hook Linux up to one SPI bus, with the
26 AVR and a DataFlash chip; and to the AVR reset 26 AVR and a DataFlash chip; and to the AVR reset line. This is all you
27 need to reflash the firmware, and the pins are 27 need to reflash the firmware, and the pins are the standard Atmel "ISP"
28 connector pins (used also on non-Butterfly AVR 28 connector pins (used also on non-Butterfly AVR boards). On the parport
29 side this is like "sp12" programming cables. 29 side this is like "sp12" programming cables.
30 30
31 ====== ============= ============ 31 ====== ============= ===================
32 Signal Butterfly Parport (DB- 32 Signal Butterfly Parport (DB-25)
33 ====== ============= ============ 33 ====== ============= ===================
34 SCK J403.PB1/SCK pin 2/D0 34 SCK J403.PB1/SCK pin 2/D0
35 RESET J403.nRST pin 3/D1 35 RESET J403.nRST pin 3/D1
36 VCC J403.VCC_EXT pin 8/D6 36 VCC J403.VCC_EXT pin 8/D6
37 MOSI J403.PB2/MOSI pin 9/D7 37 MOSI J403.PB2/MOSI pin 9/D7
38 MISO J403.PB3/MISO pin 11/S7,nB 38 MISO J403.PB3/MISO pin 11/S7,nBUSY
39 GND J403.GND pin 23/GND 39 GND J403.GND pin 23/GND
40 ====== ============= ============ 40 ====== ============= ===================
41 41
42 Then to let Linux master that bus to talk to t 42 Then to let Linux master that bus to talk to the DataFlash chip, you must
43 (a) flash new firmware that disables SPI (set 43 (a) flash new firmware that disables SPI (set PRR.2, and disable pullups
44 by clearing PORTB.[0-3]); (b) configure the mt 44 by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
45 (c) cable in the chipselect. 45 (c) cable in the chipselect.
46 46
47 ====== ============ ============ 47 ====== ============ ===================
48 Signal Butterfly Parport (DB- 48 Signal Butterfly Parport (DB-25)
49 ====== ============ ============ 49 ====== ============ ===================
50 VCC J400.VCC_EXT pin 7/D5 50 VCC J400.VCC_EXT pin 7/D5
51 SELECT J400.PB0/nSS pin 17/C3,nS 51 SELECT J400.PB0/nSS pin 17/C3,nSELECT
52 GND J400.GND pin 24/GND 52 GND J400.GND pin 24/GND
53 ====== ============ ============ 53 ====== ============ ===================
54 54
55 Or you could flash firmware making the AVR int 55 Or you could flash firmware making the AVR into an SPI slave (keeping the
56 DataFlash in reset) and tweak the spi_butterfl 56 DataFlash in reset) and tweak the spi_butterfly driver to make it bind to
57 the driver for your custom SPI-based protocol. 57 the driver for your custom SPI-based protocol.
58 58
59 The "USI" controller, using J405, can also be 59 The "USI" controller, using J405, can also be used for a second SPI bus.
60 That would let you talk to the AVR using custo 60 That would let you talk to the AVR using custom SPI-with-USI firmware,
61 while letting either Linux or the AVR use the 61 while letting either Linux or the AVR use the DataFlash. There are plenty
62 of spare parport pins to wire this one up, suc 62 of spare parport pins to wire this one up, such as:
63 63
64 ====== ============= ============ 64 ====== ============= ===================
65 Signal Butterfly Parport (DB- 65 Signal Butterfly Parport (DB-25)
66 ====== ============= ============ 66 ====== ============= ===================
67 SCK J403.PE4/USCK pin 5/D3 67 SCK J403.PE4/USCK pin 5/D3
68 MOSI J403.PE5/DI pin 6/D4 68 MOSI J403.PE5/DI pin 6/D4
69 MISO J403.PE6/DO pin 12/S5,nP 69 MISO J403.PE6/DO pin 12/S5,nPAPEROUT
70 GND J403.GND pin 22/GND 70 GND J403.GND pin 22/GND
71 71
72 IRQ J402.PF4 pin 10/S6,AC 72 IRQ J402.PF4 pin 10/S6,ACK
73 GND J402.GND(P2) pin 25/GND 73 GND J402.GND(P2) pin 25/GND
74 ====== ============= ============ 74 ====== ============= ===================
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