Intro to Inline Assembly on the Spark Core #1

sparkAssembly1.cpp

//--------------------------------------------------
// Intro to Inline Assembly on the Spark Core (WIP)
//==================================================
// Copy this into a new application at:
// https://www.spark.io/build and go nuts!
//--------------------------------------------------
// Technobly / BDub - Jan 2014
//==================================================

uint16_t pin = D0;

void setup() {
    pinMode(pin,OUTPUT);
}

void loop() {
    // Bit-Bang Digital Output D7 at 18MHz = System Clock 72MHz / 4
    // HIGH time = 27.7ns
    // LOW time = 27.7ns
    PIN_MAP[pin].gpio_peripheral->BSRR = PIN_MAP[pin].gpio_pin; // HIGH
    asm volatile(
        "nop" "\n\t"
        "nop" "\n\t"
        "nop" "\n\t"
        );
    PIN_MAP[pin].gpio_peripheral->BRR = PIN_MAP[pin].gpio_pin;  // LOW
    asm volatile(
        "nop" "\n\t"
        "nop" "\n\t"
        "nop" "\n\t"
        );
    PIN_MAP[pin].gpio_peripheral->BSRR = PIN_MAP[pin].gpio_pin; // HIGH
    asm volatile(
        "nop" "\n\t"
        "nop" "\n\t"
        );
    PIN_MAP[pin].gpio_peripheral->BRR = PIN_MAP[pin].gpio_pin;  // LOW
    asm volatile(
        "nop" "\n\t"
        "nop" "\n\t"
        );
    PIN_MAP[pin].gpio_peripheral->BSRR = PIN_MAP[pin].gpio_pin; // HIGH
    asm volatile("nop\n\t");
    PIN_MAP[pin].gpio_peripheral->BRR = PIN_MAP[pin].gpio_pin;  // LOW
    asm volatile("nop\n\t");
    PIN_MAP[pin].gpio_peripheral->BSRR = PIN_MAP[pin].gpio_pin; // HIGH
    asm volatile("nop\n\t");
    PIN_MAP[pin].gpio_peripheral->BRR = PIN_MAP[pin].gpio_pin;  // LOW
}