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Diffstat (limited to 'Documentation/spi/butterfly')
| -rw-r--r-- | Documentation/spi/butterfly | 68 |
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diff --git a/Documentation/spi/butterfly b/Documentation/spi/butterfly deleted file mode 100644 index 9927af7a629c..000000000000 --- a/Documentation/spi/butterfly +++ /dev/null @@ -1,68 +0,0 @@ -spi_butterfly - parport-to-butterfly adapter driver -=================================================== - -This is a hardware and software project that includes building and using -a parallel port adapter cable, together with an "AVR Butterfly" to run -firmware for user interfacing and/or sensors. A Butterfly is a $US20 -battery powered card with an AVR microcontroller and lots of goodies: -sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to -develop firmware for this, and flash it using this adapter cable. - -You can make this adapter from an old printer cable and solder things -directly to the Butterfly. Or (if you have the parts and skills) you -can come up with something fancier, providing ciruit protection to the -Butterfly and the printer port, or with a better power supply than two -signal pins from the printer port. Or for that matter, you can use -similar cables to talk to many AVR boards, even a breadboard. - -This is more powerful than "ISP programming" cables since it lets kernel -SPI protocol drivers interact with the AVR, and could even let the AVR -issue interrupts to them. Later, your protocol driver should work -easily with a "real SPI controller", instead of this bitbanger. - - -The first cable connections will hook Linux up to one SPI bus, with the -AVR and a DataFlash chip; and to the AVR reset line. This is all you -need to reflash the firmware, and the pins are the standard Atmel "ISP" -connector pins (used also on non-Butterfly AVR boards). On the parport -side this is like "sp12" programming cables. - - Signal Butterfly Parport (DB-25) - ------ --------- --------------- - SCK = J403.PB1/SCK = pin 2/D0 - RESET = J403.nRST = pin 3/D1 - VCC = J403.VCC_EXT = pin 8/D6 - MOSI = J403.PB2/MOSI = pin 9/D7 - MISO = J403.PB3/MISO = pin 11/S7,nBUSY - GND = J403.GND = pin 23/GND - -Then to let Linux master that bus to talk to the DataFlash chip, you must -(a) flash new firmware that disables SPI (set PRR.2, and disable pullups -by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and -(c) cable in the chipselect. - - Signal Butterfly Parport (DB-25) - ------ --------- --------------- - VCC = J400.VCC_EXT = pin 7/D5 - SELECT = J400.PB0/nSS = pin 17/C3,nSELECT - GND = J400.GND = pin 24/GND - -Or you could flash firmware making the AVR into an SPI slave (keeping the -DataFlash in reset) and tweak the spi_butterfly driver to make it bind to -the driver for your custom SPI-based protocol. - -The "USI" controller, using J405, can also be used for a second SPI bus. -That would let you talk to the AVR using custom SPI-with-USI firmware, -while letting either Linux or the AVR use the DataFlash. There are plenty -of spare parport pins to wire this one up, such as: - - Signal Butterfly Parport (DB-25) - ------ --------- --------------- - SCK = J403.PE4/USCK = pin 5/D3 - MOSI = J403.PE5/DI = pin 6/D4 - MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT - GND = J403.GND = pin 22/GND - - IRQ = J402.PF4 = pin 10/S6,ACK - GND = J402.GND(P2) = pin 25/GND - |