void refreshDisplay(displayRGB16x32 *display) // Load image to display
{
uint32_t delay = 10; // Define clock pulse delay
//CtrlPort &= ~(A+B+C+D+OE+CLK+STB); // Clear control pins
//CtrlPort |= OE;
// Transmit image to display
uint8_t i;
int8_t j;
for(i=0; i<8; i++) // Transmit each row
{
// Set row address
CtrlPort = (i & 1) ? (CtrlPort | A) : (CtrlPort & ~A);
CtrlPort = (i & 2) ? (CtrlPort | B) : (CtrlPort & ~B);
CtrlPort = (i & 4) ? (CtrlPort | C) : (CtrlPort & ~C);
CtrlPort = (i & 8) ? (CtrlPort | D) : (CtrlPort & ~D);
uint32_t bitmask = BIT(31);
for(j=31; j>=0; j--) // Transmit each pixel in each row
{
if(display->redRow[i] & bitmask) DataPort_R0R1 |= R0;
else DataPort_R0R1 &= ~R0;
if(display->redRow[i+8] & bitmask) DataPort_R0R1 |= R1;
else DataPort_R0R1 &= ~R1;
if(display->greenRow[i] & bitmask) DataPort_G0 |= G0;
else DataPort_G0 &= ~G0;
if(display->greenRow[i+8] & bitmask) DataPort_G1 |= G1;
else DataPort_G1 &= ~G1;
if(display->blueRow[i] & bitmask) DataPort_B0B1 |= B0;
else DataPort_B0B1 &= ~B0;
if(display->blueRow[i+8] & bitmask) DataPort_B0B1 |= B1;
else DataPort_B0B1 &= ~B1;
// Clock pulse
delayCycles(delay);
CtrlPort &= ~CLK;
delayCycles(delay);
CtrlPort |= CLK;
// Update bitmask
bitmask = bitmask >> 1;
}
// Latch and flash row
CtrlPort |= STB; // Latch data
delayCycles(delay);
CtrlPort &= ~STB; // Clear latch
delayCycles(delay);
CtrlPort &= ~OE; // Enable LED output
delayCycles(500);
CtrlPort |= OE; // Disable LED output
}
}
/** Set up the PIC32 ADC to sample from AN2 periodically using Timer3 as the
* trigger. DMA is used to move the ADC result into #adc_sample_buffer. */
void initADC(void)
{
// Initialise DMA module and DMA channel 0.
// Why use DMA? DMA transfers will continue even when interrupts are
// disabled, making sampling more robust (especially against USB
// activity). DMA transfers also introduce less interference into the
// signal, compared to using an interrupt service handler.
DMACONbits.ON = 0; // disable DMA controller
asm("nop"); // just to be safe
IEC1bits.DMA0IE = 0; // disable DMA channel 0 interrupt
IFS1bits.DMA0IF = 0; // clear DMA channel 0 interrupt flag
DMACONbits.ON = 1; // enable DMA controller
DMACONbits.SUSPEND = 0; // disable DMA suspend
DCH0CON = 0;
DCH0CONbits.CHPRI = 3; // priority = highest
DCH0ECON = 0;
DCH0ECONbits.CHSIRQ = _ADC_IRQ; // start transfer on ADC interrupt
DCH0ECONbits.SIRQEN = 1; // start cell transfer on IRQ
DCH0INTCLR = 0x00ff00ff; // clear existing events, disable all interrupts
// Initialise ADC module.
AD1CON1bits.ON = 0; // turn ADC module off
asm("nop"); // just to be safe
// This follows section 17.4 of the PIC32 family reference manual.
AD1PCFGbits.PCFG2 = 0; // set AN2 pin to analog mode
TRISBbits.TRISB2 = 1; // set RB2 as input (disable digital output)
TRISCbits.TRISC13 = 1; // set RC13 as input (disable digital output)
TRISCbits.TRISC14 = 1; // set RC14 as input (disable digital output)
AD1CHSbits.CH0SA = 2; // select AN2 as MUX A positive source
AD1CHSbits.CH0NA = 0; // select AVss as MUX a negative source
AD1CON1bits.FORM = 4; // output format = 32 bit integer
AD1CON1bits.SSRC = 2; // use Timer3 to trigger conversions
AD1CON1bits.ASAM = 1; // enable automatic sampling
AD1CON2bits.VCFG = 0; // use AVdd/AVss as references
AD1CON2bits.CSCNA = 0; // disable scan mode
AD1CON2bits.SMPI = 0; // 1 sample per interrupt
AD1CON2bits.BUFM = 0; // single buffer mode
AD1CON2bits.ALTS = 0; // disable alternate mode (always use MUX A)
AD1CON3bits.ADRC = 0; // derive ADC conversion clock from PBCLK
// Don't need to set SAMC since ADC is not in auto-convert (continuous)
// mode.
//AD1CON3bits.SAMC = 12; // sample time = 12 ADC conversion clocks
AD1CON3bits.ADCS = 15; // ADC conversion clock = 2.25 MHz
AD1CON1bits.SIDL = 1; // discontinue operation in idle mode
AD1CON1bits.CLRASAM = 0; // don't clear ASAM; overwrite buffer contents
AD1CON1bits.SAMP = 0; // don't start sampling immediately
AD1CON2bits.OFFCAL = 0; // disable offset calibration mode
AD1CON1bits.ON = 1; // turn ADC module on
IFS1bits.AD1IF = 0; // clear interrupt flag
IEC1bits.AD1IE = 0; // disable interrupt
delayCycles(4 * CYCLES_PER_MICROSECOND); // wait 4 microsecond for ADC to stabilise
// Initialise Timer3 to trigger ADC conversions.
T3CONbits.ON = 0; // turn timer off
T3CONbits.SIDL = 0; // continue operation in idle mode
T3CONbits.TCKPS = 0; // 1:1 prescaler
T3CONbits.TGATE = 0; // disable gated time accumulation
T3CONbits.SIDL = 0; // continue in idle mode
TMR3 = 0; // clear count
PR3 = 1500; // frequency = 48000 Hz
IFS0bits.T3IF = 0; // clear interrupt flag
IEC0bits.T3IE = 0; // disable timer interrupt
T3CONbits.ON = 1; // turn timer on
}
