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butterfly

butterfly 2.3 KB
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  1. spi_butterfly - parport-to-butterfly adapter driver
    2. 

  2. ===================================================
    3. 

  3. 

  4. This is a hardware and software project that includes building and using
    5. 

  5. a parallel port adapter cable, together with an "AVR Butterfly" to run
    6. 

  6. firmware for user interfacing and/or sensors.  A Butterfly is a $US20
    7. 

  7. battery powered card with an AVR microcontroller and lots of goodies:
    8. 

  8. sensors, LCD, flash, toggle stick, and more.  You can use AVR-GCC to
    9. 

  9. develop firmware for this, and flash it using this adapter cable.
    10. 

  10. 

  11. You can make this adapter from an old printer cable and solder things
    12. 

  12. directly to the Butterfly.  Or (if you have the parts and skills) you
    13. 

  13. can come up with something fancier, providing ciruit protection to the
    14. 

  14. Butterfly and the printer port, or with a better power supply than two
    15. 

  15. signal pins from the printer port.
    16. 

  16. 

  17. 

  18. The first cable connections will hook Linux up to one SPI bus, with the
    19. 

  19. AVR and a DataFlash chip; and to the AVR reset line.  This is all you
    20. 

  20. need to reflash the firmware, and the pins are the standard Atmel "ISP"
    21. 

  21. connector pins (used also on non-Butterfly AVR boards).
    22. 

  22. 

  23. 	Signal	  Butterfly	  Parport (DB-25)
    24. 

  24. 	------	  ---------	  ---------------
    25. 

  25. 	SCK	= J403.PB1/SCK	= pin 2/D0
    26. 

  26. 	RESET	= J403.nRST	= pin 3/D1
    27. 

  27. 	VCC	= J403.VCC_EXT	= pin 8/D6
    28. 

  28. 	MOSI	= J403.PB2/MOSI	= pin 9/D7
    29. 

  29. 	MISO	= J403.PB3/MISO	= pin 11/S7,nBUSY
    30. 

  30. 	GND	= J403.GND	= pin 23/GND
    31. 

  31. 

  32. Then to let Linux master that bus to talk to the DataFlash chip, you must
    33. 

  33. (a) flash new firmware that disables SPI (set PRR.2, and disable pullups
    34. 

  34. by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and
    35. 

  35. (c) cable in the chipselect.
    36. 

  36. 

  37. 	Signal	  Butterfly	  Parport (DB-25)
    38. 

  38. 	------	  ---------	  ---------------
    39. 

  39. 	VCC	= J400.VCC_EXT	= pin 7/D5
    40. 

  40. 	SELECT	= J400.PB0/nSS	= pin 17/C3,nSELECT
    41. 

  41. 	GND	= J400.GND	= pin 24/GND
    42. 

  42. 

  43. The "USI" controller, using J405, can be used for a second SPI bus.  That
    44. 

  44. would let you talk to the AVR over SPI, running firmware that makes it act
    45. 

  45. as an SPI slave, while letting either Linux or the AVR use the DataFlash.
    46. 

  46. There are plenty of spare parport pins to wire this one up, such as:
    47. 

  47. 

  48. 	Signal	  Butterfly	  Parport (DB-25)
    49. 

  49. 	------	  ---------	  ---------------
    50. 

  50. 	SCK	= J403.PE4/USCK	= pin 5/D3
    51. 

  51. 	MOSI	= J403.PE5/DI	= pin 6/D4
    52. 

  52. 	MISO	= J403.PE6/DO	= pin 12/S5,nPAPEROUT
    53. 

  53. 	GND	= J403.GND	= pin 22/GND
    54. 

  54. 

  55. 	IRQ	= J402.PF4	= pin 10/S6,ACK
    56. 

  56. 	GND	= J402.GND(P2)	= pin 25/GND
    57. 

  57.