void BaseDMD::scanDisplay()
{
if(pin_other_cs >= 0 && digitalRead(pin_other_cs) != HIGH)
return;
// Rows are send out in 4 blocks of 4 (interleaved), across all panels
int rowsize = unified_width() / 8; // in bytes
volatile uint8_t *bmp = bitmap;
volatile uint8_t *rows[4] = { // Scanning out 4 interleaved rows
bmp + (scan_row + 0) * rowsize,
bmp + (scan_row + 4) * rowsize,
bmp + (scan_row + 8) * rowsize,
bmp + (scan_row + 12) * rowsize,
};
writeSPIData(rows, rowsize);
digitalWrite(pin_noe, LOW);
digitalWrite(pin_sck, HIGH); // Latch DMD shift register output
digitalWrite(pin_sck, LOW); // (Deliberately left as digitalWrite to ensure decent latching time)
// A, B determine which set of interleaved rows we are multiplexing on
// 0 = 1,5,9,13
// 1 = 2,6,10,14
// 2 = 3,7,11,15
// 3 = 4,8,12,16
digitalWrite(pin_a, scan_row & 0x01);
digitalWrite(pin_b, scan_row & 0x02);
scan_row = (scan_row + 1) % 4;
if(brightness == 255)
digitalWrite(pin_noe, HIGH);
else
analogWrite(pin_noe, brightness);
}
void BaseDMD::scanDisplay()
{
if(pin_other_cs >= 0 && digitalRead(pin_other_cs) != HIGH)
return;
// Rows are send out in 4 blocks of 4 (interleaved), across all panels
int rowsize = unified_width_bytes();
volatile uint8_t *rows[4] = { // Scanning out 4 interleaved rows
bitmap + (scan_row + 0) * rowsize,
bitmap + (scan_row + 4) * rowsize,
bitmap + (scan_row + 8) * rowsize,
bitmap + (scan_row + 12) * rowsize,
};
writeSPIData(rows, rowsize);
digitalWrite(pin_noe, LOW);
digitalWrite(pin_sck, HIGH); // Latch DMD shift register output
digitalWrite(pin_sck, LOW); // (Deliberately left as digitalWrite to ensure decent latching time)
// Digital outputs A, B are a 2-bit selector output, set from the scan_row variable (loops over 0-3),
// that determines which set of interleaved rows we are outputting during this pass.
// BA 0 (00) = 1,5,9,13
// BA 1 (01) = 2,6,10,14
// BA 2 (10) = 3,7,11,15
// BA 3 (11) = 4,8,12,16
digitalWrite(pin_a, scan_row & 0x01);
digitalWrite(pin_b, scan_row & 0x02);
scan_row = (scan_row + 1) % 4;
// Output enable pin is either fixed on, or PWMed for a variable brightness display
if(brightness == 255)
digitalWrite(pin_noe, HIGH);
else
analogWrite(pin_noe, brightness);
}
