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static unsigned long const baud_rate = 57600; // Ca. 5760 bytes per second, we send one byte per state so 100 bytes per second.
static int const pin_clk = 2; // Red, the clock.
static int const pin_d0 = 3; // Yellow, the data PIN (corresponds to Q8 or Q7 for workaround).
static int const pin_strobe = 4; // Orange, resets the shift register.
// The first bit to be read. This is usually 1 but can be used as a workaround if D0 is connected to Q7 instead of Q8
// and the A button is sent last.
static int const first_bit = 1;
static uint8_t read();
void setup()
{
Serial.begin(baud_rate);
pinMode(pin_clk, OUTPUT);
pinMode(pin_d0, INPUT);
pinMode(pin_strobe, OUTPUT);
digitalWrite(pin_clk, LOW);
digitalWrite(pin_strobe, LOW);
}
void loop()
{
static auto last = uint8_t{ 0 };
auto const curr = read();
if (curr != last)
{
Serial.write(~curr);
last = curr;
}
delay(10);
}
uint8_t read()
{
// https://web.archive.org/web/20160709181841/http://www.mit.edu/~tarvizo/nes-controller.html
auto res = uint8_t{ 0 };
digitalWrite(pin_strobe, HIGH);
delayMicroseconds(12);
digitalWrite(pin_strobe, LOW);
for (int i = 0; i < 8; ++i)
{
uint8_t button = digitalRead(pin_d0);
int bit = (first_bit + i) % 8;
res |= button << bit;
delayMicroseconds(6);
digitalWrite(pin_clk, HIGH);
delayMicroseconds(6);
digitalWrite(pin_clk, LOW);
}
delayMicroseconds(6);
digitalWrite(pin_clk, HIGH);
delayMicroseconds(6);
digitalWrite(pin_clk, LOW);
return res;
}
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