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hardware_spi_example

A more polished example using the Arduino hardware SPI (does not work as-is on the Mega).

/* Ports and Pins
 
 Direct port access is much faster than digitalWrite.
 You must match the correct port and pin as shown in the table below.
 
 Arduino Pin        Port        Pin
 13 (SCK)           PORTB       5
 12 (MISO)          PORTB       4
 11 (MOSI)          PORTB       3
 10 (SS)            PORTB       2
 9                  PORTB       1
 8                  PORTB       0
 7                  PORTD       7
 6                  PORTD       6
 5                  PORTD       5
 4                  PORTD       4
 3                  PORTD       3
 2                  PORTD       2
 1 (TX)             PORTD       1
 0 (RX)             PORTD       0
 A5 (Analog)        PORTC       5
 A4 (Analog)        PORTC       4
 A3 (Analog)        PORTC       3
 A2 (Analog)        PORTC       2
 A1 (Analog)        PORTC       1
 A0 (Analog)        PORTC       0
 
 */
 
// Defines for use with Arduino functions
#define clockpin   13 // CI
#define enablepin  10 // EI
#define latchpin    9 // LI
#define datapin    11 // DI
 
// Defines for direct port access
#define CLKPORT PORTB
#define ENAPORT PORTB
#define LATPORT PORTB
#define DATPORT PORTB
#define CLKPIN  5
#define ENAPIN  2
#define LATPIN  1
#define DATPIN  3
 
// Variables for communication
unsigned long SB_CommandPacket;
int SB_CommandMode;
int SB_BlueCommand;
int SB_RedCommand;
int SB_GreenCommand;
 
// Define number of ShiftBrite modules
#define NumLEDs 2
 
// Create LED value storage array
int LEDChannels[NumLEDs][3] = {0};
 
// Set pins to outputs and initial states
void setup() {
  pinMode(datapin, OUTPUT);
  pinMode(latchpin, OUTPUT);
  pinMode(enablepin, OUTPUT);
  pinMode(clockpin, OUTPUT);
  digitalWrite(latchpin, LOW);
  digitalWrite(enablepin, LOW);
  SPCR = (1<<SPE)|(1<<MSTR)|(0<<SPR1)|(0<<SPR0);
}
 
// Load values into SPI register
void SB_SendPacket() {
 
    if (SB_CommandMode == B01) {
     SB_RedCommand = 127;
     SB_GreenCommand = 110;
     SB_BlueCommand = 110;
    }
 
    SPDR = SB_CommandMode << 6 | SB_BlueCommand>>4;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_BlueCommand<<4 | SB_RedCommand>>6;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_RedCommand << 2 | SB_GreenCommand>>8;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_GreenCommand;
    while(!(SPSR & (1<<SPIF)));
 
}
 
// Latch values into PWM registers
void SB_Latch() {
 
  delayMicroseconds(1);
  LATPORT += (1 << LATPIN);
  //ENAPORT += (1 << ENAPIN);
  delayMicroseconds(1);
  //ENAPORT &= ~(1 << ENAPIN);
  LATPORT &= ~(1 << LATPIN);
 
}
 
// Send all array values to chain
void WriteLEDArray() {
 
  SB_CommandMode = B00; // Write to PWM control registers
 
  for (int i = 0; i<NumLEDs; i++) {
    SB_RedCommand = LEDChannels[i][0] & 1023;
    SB_GreenCommand = LEDChannels[i][1] & 1023;
    SB_BlueCommand = LEDChannels[i][2] & 1023;
    SB_SendPacket();
  }
 
  SB_Latch();
 
  SB_CommandMode = B01; // Write to current control registers
 
  for (int z = 0; z < NumLEDs; z++) SB_SendPacket();   
 
  SB_Latch();
 
}
 
// Fade between two colors at specified interval
void fadeall(int rate, int fromred, int fromgreen, int fromblue, int tored, int togreen, int toblue) {
 
 for (int i = 0; i < 33; i++) {
 
     for (int j1 = 0; j1 < NumLEDs; j1++) {
       LEDChannels[j1][0] = (fromred * (32 - i) + tored * i)/32;
       LEDChannels[j1][1] = (fromgreen * (32 - i) + togreen * i)/32;
       LEDChannels[j1][2] = (fromblue * (32 - i) + toblue * i)/32;
     }
 
    WriteLEDArray();
    delay(rate);
 
   }   
}
 
void loop() {
 
  fadeall(20,0,0,0,1023,0,0);
  fadeall(20,1023,0,0,0,1023,0);
  fadeall(20,0,1023,0,0,0,1023);
  fadeall(20,0,0,1023,1023,0,0);
  fadeall(20,1023,0,0,0,0,0);
 
  delay(500);
  fadeall(60,0,0,0,0,0,1023);
  delay(500);
  fadeall(60,0,0,1023,0,0,0);  
  delay(500);
 
}
/home/macetec/public_html/docs/data/pages/hardware_spi_example.txt · Last modified: 2011/05/01 02:04 by macegr