Started following some tutorial on att85 usi. Downloaded example code from make avr book.

2022-09-20 01:08:01 -04:00
parent d0cbc0000e
commit 361a828c46
295 changed files with 68746 additions and 0 deletions
--- a/Examples/Chapter12_Analog-to-Digital-Conversion-II/footstepDetector/footstepDetector.c
+++ b/Examples/Chapter12_Analog-to-Digital-Conversion-II/footstepDetector/footstepDetector.c
@@ -0,0 +1,98 @@
+/*
+ *      Sensitive footstep-detector and EWMA demo
+ */
+
+// ------- Preamble -------- //
+#include <avr/io.h>
+#include <util/delay.h>
+#include <avr/sleep.h>
+#include "pinDefines.h"
+#include "USART.h"
+
+#define ON_TIME            2000                        /* milliseconds */
+#define CYCLE_DELAY          10                        /* milliseconds */
+#define INITIAL_PADDING  16                /* higher is less sensitive */
+
+#define SWITCH              PB7     /* Attach LED or switch relay here */
+
+#define USE_POT               0  /* define to 1 if using potentiometer */
+#if USE_POT
+#define POT               PC5                  /* optional padding pot */
+#endif
+
+// -------- Functions --------- //
+void initADC(void) {
+  ADMUX |= (1 << REFS0);                  /* reference voltage to AVCC */
+  ADCSRA |= (1 << ADPS1) | (1 << ADPS2);    /* ADC clock prescaler /64 */
+  ADCSRA |= (1 << ADEN);                                 /* enable ADC */
+}
+
+uint16_t readADC(uint8_t channel) {
+  ADMUX = (0b11110000 & ADMUX) | channel;
+  ADCSRA |= (1 << ADSC);
+  loop_until_bit_is_clear(ADCSRA, ADSC);
+  return (ADC);
+}
+
+int main(void) {
+  // -------- Inits --------- //
+  uint16_t lightsOutTimer = 0;                 /* timer for the switch */
+  uint16_t adcValue;
+  uint16_t middleValue = 511;
+  uint16_t highValue = 520;
+  uint16_t lowValue = 500;
+  uint16_t noiseVolume = 0;
+  uint8_t padding = INITIAL_PADDING;
+
+  LED_DDR = ((1 << LED0) | (1 << LED1) | (1 << SWITCH));
+  initADC();
+  initUSART();
+
+  // ------ Event loop ------ //
+  while (1) {
+    adcValue = readADC(PIEZO);
+
+                     /* moving average -- tracks sensor's bias voltage */
+    middleValue = adcValue + middleValue - ((middleValue - 8) >> 4);
+          /* moving averages for positive and negative parts of signal */
+    if (adcValue > (middleValue >> 4)) {
+      highValue = adcValue + highValue - ((highValue - 8) >> 4);
+    }
+    if (adcValue < (middleValue >> 4)) {
+      lowValue = adcValue + lowValue - ((lowValue - 8) >> 4);
+    }
+            /* "padding" provides a minimum value for the noise volume */
+    noiseVolume = highValue - lowValue + padding;
+
+            /* Now check to see if ADC value above or below thresholds */
+                /* Comparison with >> 4 b/c EWMA is on different scale */
+    if (adcValue < ((middleValue - noiseVolume) >> 4)) {
+      LED_PORT = (1 << LED0) | (1 << SWITCH);       /* one LED, switch */
+      lightsOutTimer = ON_TIME / CYCLE_DELAY;           /* reset timer */
+    }
+    else if (adcValue > ((middleValue + noiseVolume) >> 4)) {
+      LED_PORT = (1 << LED1) | (1 << SWITCH);     /* other LED, switch */
+      lightsOutTimer = ON_TIME / CYCLE_DELAY;           /* reset timer */
+    }
+    else {                            /* Nothing seen, turn off lights */
+      LED_PORT &= ~(1 << LED0);
+      LED_PORT &= ~(1 << LED1);                            /* Both off */
+      if (lightsOutTimer > 0) {                  /* time left on timer */
+        lightsOutTimer--;
+      }
+      else {                                              /* time's up */
+        LED_PORT &= ~(1 << SWITCH);                 /* turn switch off */
+      }
+    }
+#if USE_POT                          /* optional padding potentiometer */
+    padding = readADC(POT) >> 4;         /* scale down to useful range */
+#endif
+                                            /* Serial output and delay */
+           /* ADC is 10-bits, recenter around 127 for display purposes */
+    transmitByte(adcValue - 512 + 127);
+    transmitByte((lowValue >> 4) - 512 + 127);
+    transmitByte((highValue >> 4) - 512 + 127);
+    _delay_ms(CYCLE_DELAY);
+  }                                                  /* End event loop */
+  return 0;                            /* This line is never reached */
+}