TLC5940.cpp

00001 #include "TLC5940.h"
00002 
00003 TLC5940::TLC5940(PinName SCLK, PinName MOSI, PinName GSCLK, PinName BLANK, 
00004                  PinName XLAT, PinName DCPRG, PinName VPRG, const int number) : number(number),
00005                                                                                 spi(MOSI, NC, SCLK),
00006                                                                                 gsclk(GSCLK),
00007                                                                                 blank(BLANK),
00008                                                                                 xlat(XLAT),
00009                                                                                 dcprg(DCPRG),
00010                                                                                 vprg(VPRG),
00011                                                                                 newGSData(false),
00012                                                                                 newDCData(false),
00013                                                                                 need_xlat(false)
00014 {   
00015     // Configure SPI to 12 bits and SPI_SPEED
00016     spi.format(12, 0);
00017     spi.frequency(SPI_SPEED);
00018     
00019     // Set output pin states
00020     dcprg = 0;
00021     vprg = 0;
00022     xlat = 0;
00023     blank = 1;
00024     
00025     // Call the reset function every 4096 PWM outputs
00026     reset_ticker.attach_us(this, &TLC5940::reset, (1000000.0/GSCLK_SPEED) * 4096.0);
00027     
00028     // Configure FastPWM output for GSCLK frequency at 50% duty cycle
00029     gsclk.period_us(1000000.0/(GSCLK_SPEED * 1.05));
00030     gsclk.write(.5);
00031 }
00032 
00033 void TLC5940::setNewGSData(unsigned short* data)
00034 {
00035     gsBuffer = data;
00036     
00037     // Tell reset function that new GS data has been given
00038     newGSData = true;
00039 }
00040 
00041 void TLC5940::setNewDCData(unsigned char* data)
00042 {
00043     dcBuffer = data;
00044     
00045     // Tell reset function that new DC data has been given
00046     newDCData = true;
00047 }
00048 
00049 void TLC5940::reset()
00050 {
00051     gsclk.write(0);
00052     // Turn off LEDs
00053     blank = 1;
00054     
00055     // Virtual function that allows the next data chunk to be set after every GSCLK cycle
00056     // Useful for setting the next frame when multiplexing (e.g. LED matrices)
00057     setNextData();
00058     
00059     // Latch in data from previous cycle if needed
00060     if (need_xlat)
00061     {
00062         // Latch
00063         xlat = 1;
00064         xlat = 0;
00065         
00066         // Don't need to latch again
00067         need_xlat = false;
00068     }
00069     
00070     // Reset the screen so that it is updating while data is being sent
00071     blank = 0;
00072     gsclk.write(.5);
00073     
00074     // Do we have new DC data to send?
00075     if (newDCData)
00076     {
00077         // Set TLC5940 to accpet DC data
00078         vprg = 1;
00079         
00080         // Get DC data from registers instead of EEPROM (since we are sending data to the registers now)
00081         dcprg = 1;
00082         
00083         // Send DC data backwards - this makes the DC_buffer[0] index correspond to OUT0
00084         for (int i = (16 * number) - 1; i >= 0; i--)
00085         {
00086             // Assemble a 12 bit packet from two 6 bit chunks
00087             spi.write(((dcBuffer[i] & 0x3F) << 6) | (dcBuffer[i-1] & 0x3F));
00088             i--;
00089         }
00090         
00091         // Latch
00092         xlat = 1;
00093         xlat = 0;
00094         
00095         // No new data to send (we just sent it!)
00096         newDCData = false;
00097     }
00098     
00099     // Do we have new GS data to send?
00100     if (newGSData)
00101     {
00102         // Set TLC5940 to accept GS data
00103         vprg = 0;
00104         
00105         // Send GS data backwards - this makes the GS_buffer[0] index correspond to OUT0 
00106         for (int i = (16 * number) - 1; i >= 0; i--)
00107         {
00108             // Get the lower 12 bits of the buffer and send
00109             spi.write(gsBuffer[i] & 0xFFF);
00110         }
00111         
00112         // Latch after current GS data is done being displayed
00113         need_xlat = true;
00114         
00115         // No new data to send (we just sent it!)
00116         newGSData = false;
00117     }
00118 }