110 lines
2.6 KiB
C
110 lines
2.6 KiB
C
#include "reflectance.h"
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#include "delay.h"
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#include "inc/msp432p401r.h"
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void ReflectanceInit(void) {
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P5->SEL0 &= ~0x08;
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P5->SEL1 &= ~0x08; // configure P5.3 as GPIO
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P5->DIR |= 0x08; // make P5.3 output
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P5->OUT &= ~0x08; // set output low
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P9->SEL0 &= ~0x04;
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P9->SEL1 &= ~0x04; // configure P9.2 as GPIO
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P9->DIR |= 0x04; // make P9.2 output
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P9->OUT &= ~0x04; // set output low
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P7->SEL0 &= ~0x255;
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P7->SEL1 &= ~0x255; // configure P7.0-7 as GPIO
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P7->DIR &= ~0x255; // make them input
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// P7->REN |= 0x255; //? enable pull resistors
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}
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// 0 -> while, 1 -> black
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uint8_t ReflectanceRead(uint32_t time) {
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uint8_t input;
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// 1) Set P5.3 and P9.2 high (turn on IR LED)
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P5->OUT |= 0x08;
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P9->OUT |= 0x04;
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// 2) Make P7.7 – P7.0 outputs, and set them high (charging 8 capacitors)
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P7->DIR |= 0x255;
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P7->OUT |= 0x255;
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// 3) Wait 10 us, Delay1us(10);
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Delay1us(10);
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// 4) Make P7.7 – P7.0 input
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P7->DIR &= ~0x255;
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// 5) Wait time us, Delay1us(time);
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Delay1us(time);
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// 6) Read P7.7 – P7.0 inputs (converts voltages into binary)
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input = P7->IN;
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// 7) Set P5.3 and P9.2 low (turn off IR LED, saving power)
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P5->OUT &= ~0x08;
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P9->OUT &= ~0x04;
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//P7->DIR &= ~0x255;
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//P7->OUT &= ~0x255;
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// 8) Return 8-bit binary measured in step 6
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return input;
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}
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int32_t ReflectancePosition(uint8_t sensor_data) {
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// Data falls into four categories:
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// 1) <all 0’s> (off the line or on white surface)
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// 2) <some 0’s, some 1’s>, e.g., 00000111 (off to the left)
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// 3) <some 0’s, some 1’s, some 0’s>, e.g., 00110000 (over the line)
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// 4) < some 1’s, some 0’s>, e.g., 11110000 (off to the right)
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int32_t W[] = {334, 238, 142, 48, -48, -142, -238, -334};
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// if (!sensor_data) return 0; // off the line or on white surface
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int32_t i, up, down, b;
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for (up = down = i = 0; i < 8; ++i) {
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b = (sensor_data & (1 << i)) != 0;
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up += b * W[i];
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down += b;
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}
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return up / down;
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}
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void ReflectanceStart(void) {
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// turn on 4 even IR LEDs
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// turn on 4 odd IR LEDs
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P5->OUT |= 0x08;
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P9->OUT |= 0x04;
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// make P7.7-P7.0 out
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P7->DIR |= 0x255;
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// prime for measurement
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P7->OUT |= 0x255;
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// wait 10 us
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Delay1us(10);
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// make P7.7-P7.0 in
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P7->DIR &= ~0x255;
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}
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uint8_t ReflectanceEnd(void) {
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uint8_t input;
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// convert P7.0 input to digital
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input = P7->IN;
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// turn off 4 even IR LEDs
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// turn off 4 odd IR LEDs
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P5->OUT &= ~0x08;
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P9->OUT &= ~0x04;
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return input;
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}
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