Difference between revisions of "Led Matrix 32x64"

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[[Category:Ongoing_Projects]]
 
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A FPGA-based interface controller for
 
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[http://www.limpkin.fr/index.php?post/2011/05/12/Oops...-I-dit-it-again%21 Limpkin's RGB LED matrices].
 
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=== Matrix reference ===
 
=== Matrix reference ===
  
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* size: 64x32 RGB LEDs
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* Size: 32x64 RGB LEDs (127x256mm)
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* organization: 2 blocks (upper and lower) with each 16 lines à 64 LEDs
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* Organization: 2 blocks (upper and lower) with each 16 lines of 64 LEDs
 
* (6) 64 bit shift registers
 
* (6) 64 bit shift registers
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* input pins:
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* 40ns period = 25MHz max.
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** R, G, B for each upper and lower: R1, G1, B1, R2, G2, B2; 1 = LED on
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* ~4A with full matrix in white color
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** clock (next bit, rising edge)
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* 5V signals
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** latch (latch shifted data to output, rising edge)
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* Serial MCU Interface
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** enable (drives LEDs from latched data?, 0 = enable)
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* Price: ~ 150.- USD
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** 5V signals
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** 40ns period = 25MHz max.
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== Overview ==
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* FPGA drives 1 or more (up to 4?) matrices
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* use block ram or external SRAM for frame buffer storage
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* interface with PC
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=== Feature ideas ===
 
  
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* double buffering
 
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* larger off-screen buffer + compositing ops?
 
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* character generation
 
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* update only sections
 
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* small CPU core to execute short programs?
 
  
  
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== Components ==
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=== Input pins ===
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# '''DR1''' - RED for lines 1-16 (1 = LED on)
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# '''DG1''' - GREEN for lines 1-16 (1 = LED on)
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# '''DB1''' - BLUE for lines 1-16 (1 = LED on)
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# '''GND''' - Ground Reference
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# '''DR2''' - RED for lines 17-32 (1 = LED on)
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# '''DG2''' - GREEN for lines 17-32 (1 = LED on)
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# '''DB2''' - BLUE for lines 17-32 (1 = LED on)
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# '''GND''' - Ground Reference
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# '''A''' - Used for the bit selection of one of 16 rows
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# '''B''' - Used for the bit selection of one of 16 rows
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# '''C''' - Used for the bit selection of one of 16 rows
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# '''D''' - Used for the bit selection of one of 16 rows
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# '''CLK''' - Clock imput for 74HC595 shift register
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# '''LAT''' - Content of 74HC595 Shift Register transferred to output latches
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# '''EN''' - Enable 74HC138 encoder to set one of 16 rows (0 = enable)
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# '''GND''' Ground Reference
  
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=== Memory ===
 
  
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External SRAM needs to be fast enough to handle all reads during one
 
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cycle.  Per connected matrix we need to read 6 bytes per cycle.
 
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Clearly this would require use to run at 150MHz, which is infeasible.
 
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If we use a separate chip per matrix block (6 chips or 3 chips with
 
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16bit width), we can still operate with 25MHz.
 
  
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Concurrent writes need to be possible, but at a lower speed.  Either
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=== Pictures ===
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buffer reads and slip in writes when there is slack (complicated), or
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[[File:Ledmatrix_1.JPG||500px]]
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alternate between reads and writes at higher speed (DDR?).
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[[File:Ledmatrix_2.JPG||500px]]

Latest revision as of 22:13, 4 September 2011

Matrix reference

  • Size: 32x64 RGB LEDs (127x256mm)
  • Organization: 2 blocks (upper and lower) with each 16 lines of 64 LEDs
  • (6) 64 bit shift registers
  • 40ns period = 25MHz max.
  • ~4A with full matrix in white color
  • 5V signals
  • Serial MCU Interface
  • Price: ~ 150.- USD



Input pins

  1. DR1 - RED for lines 1-16 (1 = LED on)
  2. DG1 - GREEN for lines 1-16 (1 = LED on)
  3. DB1 - BLUE for lines 1-16 (1 = LED on)
  4. GND - Ground Reference
  5. DR2 - RED for lines 17-32 (1 = LED on)
  6. DG2 - GREEN for lines 17-32 (1 = LED on)
  7. DB2 - BLUE for lines 17-32 (1 = LED on)
  8. GND - Ground Reference
  9. A - Used for the bit selection of one of 16 rows
  10. B - Used for the bit selection of one of 16 rows
  11. C - Used for the bit selection of one of 16 rows
  12. D - Used for the bit selection of one of 16 rows
  13. CLK - Clock imput for 74HC595 shift register
  14. LAT - Content of 74HC595 Shift Register transferred to output latches
  15. EN - Enable 74HC138 encoder to set one of 16 rows (0 = enable)
  16. GND Ground Reference


Pictures

Ledmatrix 1.JPG Ledmatrix 2.JPG

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