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authorDavid Brownell <david-b@pacbell.net>2006-01-11 14:23:49 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2006-01-13 19:29:56 -0500
commit2e10c84b9cf0b2d269c5629048d8d6e35eaf6b2b (patch)
tree2b338e8282d4e740529aeb3d5f303c4883f8d667 /Documentation/spi
parent5d870c8e216f121307445c71caa72e7e10a20061 (diff)
[PATCH] SPI: add spi_butterfly driver
This adds a bitbanging parport based adaptor cable for AVR Butterfly, giving SPI links to its DataFlash chip and (eventually) firmware running in the card. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1spi_butterfly - parport-to-butterfly adapter driver
2===================================================
3
4This is a hardware and software project that includes building and using
5a parallel port adapter cable, together with an "AVR Butterfly" to run
6firmware for user interfacing and/or sensors. A Butterfly is a $US20
7battery powered card with an AVR microcontroller and lots of goodies:
8sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to
9develop firmware for this, and flash it using this adapter cable.
10
11You can make this adapter from an old printer cable and solder things
12directly to the Butterfly. Or (if you have the parts and skills) you
13can come up with something fancier, providing ciruit protection to the
14Butterfly and the printer port, or with a better power supply than two
15signal pins from the printer port.
16
17
18The first cable connections will hook Linux up to one SPI bus, with the
19AVR and a DataFlash chip; and to the AVR reset line. This is all you
20need to reflash the firmware, and the pins are the standard Atmel "ISP"
21connector pins (used also on non-Butterfly AVR boards).
22
23 Signal Butterfly Parport (DB-25)
24 ------ --------- ---------------
25 SCK = J403.PB1/SCK = pin 2/D0
26 RESET = J403.nRST = pin 3/D1
27 VCC = J403.VCC_EXT = pin 8/D6
28 MOSI = J403.PB2/MOSI = pin 9/D7
29 MISO = J403.PB3/MISO = pin 11/S7,nBUSY
30 GND = J403.GND = pin 23/GND
31
32Then to let Linux master that bus to talk to the DataFlash chip, you must
33(a) flash new firmware that disables SPI (set PRR.2, and disable pullups
34by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
35(c) cable in the chipselect.
36
37 Signal Butterfly Parport (DB-25)
38 ------ --------- ---------------
39 VCC = J400.VCC_EXT = pin 7/D5
40 SELECT = J400.PB0/nSS = pin 17/C3,nSELECT
41 GND = J400.GND = pin 24/GND
42
43The "USI" controller, using J405, can be used for a second SPI bus. That
44would let you talk to the AVR over SPI, running firmware that makes it act
45as an SPI slave, while letting either Linux or the AVR use the DataFlash.
46There are plenty of spare parport pins to wire this one up, such as:
47
48 Signal Butterfly Parport (DB-25)
49 ------ --------- ---------------
50 SCK = J403.PE4/USCK = pin 5/D3
51 MOSI = J403.PE5/DI = pin 6/D4
52 MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT
53 GND = J403.GND = pin 22/GND
54
55 IRQ = J402.PF4 = pin 10/S6,ACK
56 GND = J402.GND(P2) = pin 25/GND
57