40 lines
1.1 KiB
Arduino
40 lines
1.1 KiB
Arduino
// Scope test for fast shiftOut function.
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#include <DigitalIO.h>
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// Create clockPin in output mode with inital level LOW.
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DigitalPin<12> clockPin(OUTPUT, LOW);
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// Create dataPin in output mode with inital level HIGH.
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DigitalPin<13> dataPin(OUTPUT, HIGH);
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//------------------------------------------------------------------------------
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// Time to send one bit is ten cycles or 625 ns for 16 MHz CPU.
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inline __attribute__((always_inline))
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void sendBit(uint8_t bit, uint8_t data) {
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dataPin = data & (1 << bit);
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clockPin = 1;
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// may want a nop here - clock pulse is 125 ns wide
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clockPin = 0;
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}
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//------------------------------------------------------------------------------
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// Time to send one byte is 5 usec.
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void shiftOut(uint8_t bits) {
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sendBit(7, bits);
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sendBit(6, bits);
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sendBit(5, bits);
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sendBit(4, bits);
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sendBit(3, bits);
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sendBit(2, bits);
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sendBit(1, bits);
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sendBit(0, bits);
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}
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//------------------------------------------------------------------------------
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void setup() {
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// Not used.
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}
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//------------------------------------------------------------------------------
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void loop() {
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shiftOut(0X55);
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delay(2);
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}
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