Commit | Line | Data |
---|---|---|
9cdd273e | 1 | =================================================== |
2e10c84b DB |
2 | spi_butterfly - parport-to-butterfly adapter driver |
3 | =================================================== | |
4 | ||
5 | This is a hardware and software project that includes building and using | |
6 | a parallel port adapter cable, together with an "AVR Butterfly" to run | |
7 | firmware for user interfacing and/or sensors. A Butterfly is a $US20 | |
8 | battery powered card with an AVR microcontroller and lots of goodies: | |
9 | sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to | |
10 | develop firmware for this, and flash it using this adapter cable. | |
11 | ||
12 | You can make this adapter from an old printer cable and solder things | |
13 | directly to the Butterfly. Or (if you have the parts and skills) you | |
d1ad0a73 | 14 | can come up with something fancier, providing circuit protection to the |
2e10c84b | 15 | Butterfly and the printer port, or with a better power supply than two |
9c1da3cb DB |
16 | signal pins from the printer port. Or for that matter, you can use |
17 | similar cables to talk to many AVR boards, even a breadboard. | |
18 | ||
19 | This is more powerful than "ISP programming" cables since it lets kernel | |
20 | SPI protocol drivers interact with the AVR, and could even let the AVR | |
21 | issue interrupts to them. Later, your protocol driver should work | |
22 | easily with a "real SPI controller", instead of this bitbanger. | |
2e10c84b DB |
23 | |
24 | ||
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 line. This is all you | |
27 | need to reflash the firmware, and the pins are the standard Atmel "ISP" | |
9c1da3cb DB |
28 | connector pins (used also on non-Butterfly AVR boards). On the parport |
29 | side this is like "sp12" programming cables. | |
2e10c84b | 30 | |
9cdd273e | 31 | ====== ============= =================== |
2e10c84b | 32 | Signal Butterfly Parport (DB-25) |
9cdd273e MCC |
33 | ====== ============= =================== |
34 | SCK J403.PB1/SCK pin 2/D0 | |
35 | RESET J403.nRST pin 3/D1 | |
36 | VCC J403.VCC_EXT pin 8/D6 | |
37 | MOSI J403.PB2/MOSI pin 9/D7 | |
38 | MISO J403.PB3/MISO pin 11/S7,nBUSY | |
39 | GND J403.GND pin 23/GND | |
40 | ====== ============= =================== | |
2e10c84b DB |
41 | |
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 PRR.2, and disable pullups | |
44 | by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and | |
45 | (c) cable in the chipselect. | |
46 | ||
9cdd273e | 47 | ====== ============ =================== |
2e10c84b | 48 | Signal Butterfly Parport (DB-25) |
9cdd273e MCC |
49 | ====== ============ =================== |
50 | VCC J400.VCC_EXT pin 7/D5 | |
51 | SELECT J400.PB0/nSS pin 17/C3,nSELECT | |
52 | GND J400.GND pin 24/GND | |
53 | ====== ============ =================== | |
2e10c84b | 54 | |
9c1da3cb DB |
55 | Or you could flash firmware making the AVR into an SPI slave (keeping the |
56 | DataFlash in reset) and tweak the spi_butterfly driver to make it bind to | |
57 | the driver for your custom SPI-based protocol. | |
58 | ||
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 custom SPI-with-USI firmware, | |
61 | while letting either Linux or the AVR use the DataFlash. There are plenty | |
62 | of spare parport pins to wire this one up, such as: | |
2e10c84b | 63 | |
9cdd273e | 64 | ====== ============= =================== |
2e10c84b | 65 | Signal Butterfly Parport (DB-25) |
9cdd273e MCC |
66 | ====== ============= =================== |
67 | SCK J403.PE4/USCK pin 5/D3 | |
68 | MOSI J403.PE5/DI pin 6/D4 | |
69 | MISO J403.PE6/DO pin 12/S5,nPAPEROUT | |
70 | GND J403.GND pin 22/GND | |
2e10c84b | 71 | |
9cdd273e MCC |
72 | IRQ J402.PF4 pin 10/S6,ACK |
73 | GND J402.GND(P2) pin 25/GND | |
74 | ====== ============= =================== |