Arduino UNOと同じmini-Oscilloscope を作って見た。
表示の正確性はまた検証が必要だけど
ソースコードはほぼ一緒
/*
This is set up to use a 128x64 I2C screen, as available
here: http://www.banggood.com/buy/0-96-oled.html
For wiring details see http://youtu.be/XHDNXXhg3Hg
*/
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
#if (SSD1306_LCDHEIGHT != 64)
// error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif
/********************************************/
#define CHARWIDTH 5
#define CHARHEIGHT 8
#define AXISWIDTH (2 + 1) // axis will show two-pixel wide graph ticks, then an empty column
#define VISIBLEVALUEPIXELS (128 - AXISWIDTH) // the number of samples visible on screen
#define NUMVALUES (2 * VISIBLEVALUEPIXELS) // the total number of samples (take twice as many as visible, to help find trigger point
#define TRIGGER_ENABLE_PIN 2 // set this pin high to enable trigger
#define SCREEN_UPDATE_ENABLE_PIN 3 // set this pin high to freeze screen
byte values[NUMVALUES]; // stores read analog values mapped to 0-63
int pos = 0; // the next position in the value array to read
int count = 0; // the total number of times through the loop
unsigned long readStartTime = 0; // time when the current sampling started
int sampleRate = 1; // A value of 1 will sample every time through the loop, 5 will sample every fifth time etc.
const int voutPin = 2;
const int VOLT = 3.3; // 3.3Vを電源とした場合
const int ANALOG_MAX = 4096; // ESP32の場合
/********************************************/
// Draws a printf style string at the current cursor position
void displayln(const char* format, ...)
{
char buffer[32];
va_list args;
va_start(args, format);
vsprintf(buffer, format, args);
va_end(args);
int len = strlen(buffer);
for (uint8_t i = 0; i < len; i++) {
display.write(buffer[i]);
}
}
// Draws the graph ticks for the vertical axis
void drawAxis()
{
// graph ticks
for (int x = 0; x < 2; x++) {
display.drawPixel(x, 0, WHITE);
display.drawPixel(x, 13, WHITE);
display.drawPixel(x, 26, WHITE);
display.drawPixel(x, 38, WHITE);
display.drawPixel(x, 50, WHITE);
display.drawPixel(x, 63, WHITE);
}
}
// Draws the sampled values
void drawValues()
{
int start = 0;
if ( digitalRead(TRIGGER_ENABLE_PIN) ) {
// Find the first occurence of zero
for (int i = 0; i < NUMVALUES; i++) {
if ( values[i] == 0 ) {
// Now find the next value that is not zero
for (; i < NUMVALUES; i++) {
if ( values[i] != 0 ) {
start = i;
break;
}
}
break;
}
}
// If the trigger point is not within half of our values, we will
// not have enough sample points to show the wave correctly
if ( start >= VISIBLEVALUEPIXELS )
return;
}
for (int i = 0; i < VISIBLEVALUEPIXELS; i++) {
display.drawPixel(i + AXISWIDTH, 63 - (values[i + start]), WHITE);
}
}
// Shows the time taken to sample the values shown on screen
void drawFrameTime(unsigned long us)
{
display.setCursor(9 * CHARWIDTH, 7 * CHARHEIGHT - 2); // almost at bottom, approximately centered
displayln("%ld us", us);
}
/********************************************/
void setup() {
// Set up the display
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Initialize with the I2C addr 0x3D (for the 128x64)
// Clear the buffer.
display.clearDisplay();
display.setTextColor(WHITE);
pinMode(TRIGGER_ENABLE_PIN, INPUT);
pinMode(SCREEN_UPDATE_ENABLE_PIN, INPUT);
}
/********************************************/
void loop() {
// If a sampling run is about to start, record the start time
if ( pos == 0 )
readStartTime = micros();
// If this iteration is one we want a sample for, take the sample
if ( (++count) % sampleRate == 0 )
values[pos++] = analogRead(voutPin) >> 6; // shifting right by 4 efficiently maps 0-1023 range to 0-63
// If we have filled the sample buffer, display the results on screen
if ( pos >= NUMVALUES ) {
// Measure how long the run took
unsigned long totalSampleTime = (micros() - readStartTime) / 2; // Divide by 2 because we are taking twice as many samples as are shown on the screen
// if ( !digitalRead(SCREEN_UPDATE_ENABLE_PIN) ) {
// Display the data on screen
display.clearDisplay();
drawAxis();
drawValues();
drawFrameTime(totalSampleTime);
display.display();
// }
// Reset values for the next sampling run
pos = 0;
count = 0;
}
}
