来自网友Johnag，使用
Arduino Mega2560和3.8寸TFT触控屏制作一个简单的示波器。
具体的使用Arduino A0脚采集数据和记录时间，使用触摸屏功能利用程序输入、调整示波器的参数、行为。
示波器参数主要包括：
1. 扫描速度、即水平灵敏度，单位距离内的数据量，波形长度。单位为毫秒/厘米，毫秒/单元格。
2. 垂直灵敏度，波形高度。单位为伏特/厘米，伏特/单元格。
3. 触发信号，捕获信号的灵敏度。只有当信号强度到达某一阀值是，才向屏幕输出、显示波形。
主要部件：
Sainsamrt Mega2560和3.8寸TFT触控屏套件触摸屏的控制代码则来自
Henning Karlsen UTFT library 和 the UTouch library （这个网站不稳定，上午能登陆，现在就打不开了，IP位于南非）
套件就是它，是那块板子，售价38美元，不知道这个sainsmart的2560和其他2560的通用性如何。
估计原作者使用这套板子，是因为他们成套地卖，连接容易，兼容性不晓得。
A0脚作为示波器的探头输入，再随便选一个地脚。这时需要把对应的排针弯曲。
全部插好，连接usb，打开arduino的开发环境，从网上下载UTFT和UTouch的库文件，copy到
ARDUINO IDE的库文件夹，打开文件菜单，选择UTFT-demo-320x240运行测试程序。
代码窗口，注释掉第一行，那行是为arduino Uno用的。取消第二行的注释，为mega用的
// Uncomment the next line for Arduino 2009/Uno
//UTFT myGLCD(ITDB32S,19,18,17,16); // Remember to change the model parameter to suit your display module!
// Uncomment the next line for Arduino Mega
UTFT myGLCD(ITDB32S,38,39,40,41); // Remember to change the model parameter to suit your display module!
剩下的就是差错，编译上传到到arduino，就应该能看到演示程序运行了。
到这步，文件菜单，Examples>UTouch>Arduino>Utouch_ButtonTest，测试触屏代码。
然后，运行示波器程序，这个示波器的带宽只有1KHz。并且数据信号最高电压只能在5V之下。
这段代码是
参考了几处 ，做了一些修改，完成代码如下。
//----------------------START PROGRAM
/*--------------------------------------------------------------
Program: OscopetouchLCDmega
Description: Digital Oscilloscope with data displayed on Color TFT LCD with touch screen
Hardware: sainsmart mega2560 board with 3.5" tft lcd touch module display and shield kit
http://www.sainsmart.com/home-page-view/sainsmart-mega2560-board-3-5-tft-lcd-module-display-shield-kit-for-atmel-atmega-avr-16au-atmega8u2.html
Software: Developed using Arduino 1.0.3 software
This program requires the UTFT library and the UTouch library from Henning Karlsen.
web: http://www.henningkarlsen.com/electronics Version 1.00
Date: 5 April 2014
Author: johnag
--------------------------------------------------------------*/
#include <UTFT.h>
#include <UTouch.h>
// Declare which fonts we will be using
extern uint8_t SmallFont[];
// Initialize Screen and touch functions
UTFT myGLCD(ITDB32S,38,39,40,41);
UTouch myTouch(6,5,4,3,2);
// Declare variables
char buf[12];
int x,y;
int Input = 0;
byte Sample[320];
byte OldSample[320];
int StartSample = 0;
int EndSample = 0;
int Max = 100;
int Min = 100;
int mode = 0;
int dTime = 1;
int tmode = 0;
int Trigger = 0;
int SampleSize = 0;
int SampleTime = 0;
int dgvh;
int hpos = 50; //set 0v on horizontal grid
int vsens = 4; // vertical sensitivity
// Define various ADC prescaler
const unsigned char PS_16 = (1 << ADPS2);
const unsigned char PS_32 = (1 << ADPS2) | (1 << ADPS0);
const unsigned char PS_64 = (1 << ADPS2) | (1 << ADPS1);
const unsigned char PS_128 = (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
//------------Start Subrutines------------------------------------
//--------draw buttons sub
void buttons(){
myGLCD.setColor(0, 0, 255);
myGLCD.fillRoundRect (250, 1, 310, 50);
myGLCD.fillRoundRect (250, 55, 310, 105);
myGLCD.fillRoundRect (250, 110, 310, 160);
myGLCD.fillRoundRect (250, 165, 310, 215);
}
//-------touchscreen position sub
void touch(){
while (myTouch.dataAvailable())
{
myTouch.read();
x=myTouch.getX();
y=myTouch.getY();
delay(500);
if ((y>=1) && (y<=50)) // Delay row
{
if ((x>=250) && (x<=300)) // Delay Button
waitForIt(250, 1, 310, 50);
mode= mode ++ ;
{
myGLCD.setColor(255, 0, 0);
myGLCD.drawRoundRect (250, 1, 310, 50);
// Select delay times
if (mode == 0) dTime = 0;
if (mode == 1) dTime = 1;
if (mode == 2) dTime = 2;
if (mode == 3) dTime = 5;
if (mode == 4) dTime = 10;
if (mode == 5) dTime = 20;
if (mode == 6) dTime = 30;
if (mode == 7) dTime = 50;
if (mode == 8) dTime = 100;
if (mode == 9) dTime = 200;
if (mode == 10) dTime = 500;
if (mode > 10) mode = 0;
}}
if ((y>=70) && (y<=120)) // Trigger row
{
if ((x>=250) && (x<=300)) // Trigger Button
waitForIt(250, 55, 310, 105);
tmode= tmode ++;
{
myGLCD.setColor(255, 0, 0);
// Select Software trigger value
myGLCD.drawRoundRect (250, 55, 310, 105);
if (tmode == 1) Trigger = 0;
if (tmode == 2) Trigger = 10;
if (tmode == 3) Trigger = 20;
if (tmode == 4) Trigger = 30;
if (tmode == 5) Trigger = 50;
if (tmode > 5)tmode = 0;
}}
if ((y>=130) && (y<=180)) // H position row
{
if ((x>=250) && (x<=300)) // H position Button
waitForIt(250, 110, 310, 160);
hpos= hpos ++;
{
myGLCD.setColor(255, 0, 0);
myGLCD.drawRoundRect (250, 110, 310, 160);
myGLCD.clrScr();
buttons();
if (hpos > 60)hpos = 50;
}}}}
//----------wait for touch sub
void waitForIt(int x1, int y1, int x2, int y2)
{
while (myTouch.dataAvailable())
myTouch.read();
}
//----------draw grid sub
void DrawGrid(){
myGLCD.setColor( 0, 200, 0);
for( dgvh = 0; dgvh < 5; dgvh ++){
myGLCD.drawLine( dgvh * 50, 0, dgvh * 50, 240);
myGLCD.drawLine( 0, dgvh * 50, 245 ,dgvh * 50);
}
myGLCD.drawLine( 245, 0, 245, 240);
myGLCD.drawLine( 0, 239, 245, 239);
myGLCD.setColor(255, 255, 255);
myGLCD.drawRoundRect (250, 1, 310, 50);
myGLCD.drawRoundRect (250, 55, 310, 105);
myGLCD.drawRoundRect (250, 110, 310, 160);
myGLCD.drawRoundRect (250, 165, 310, 215);
}
// ------ Wait for input to be greater than trigger sub
void trigger(){
while (Input < Trigger){ Input = analogRead(A0)*5/100;
}}
//---------------End Subrutines ----------------------
void setup() {
myGLCD.InitLCD();
myGLCD.clrScr();
myTouch.InitTouch();
myTouch.setPrecision(PREC_MEDIUM);
buttons();
pinMode(0, INPUT);
// set up the ADC
ADCSRA &= ~PS_128; // remove bits set by Arduino library
// you can choose a prescaler from below.
// PS_16, PS_32, PS_64 or PS_128
ADCSRA |= PS_64; // set our own prescaler
}
void loop() {
while(1) {
DrawGrid();
touch();
trigger();
// Collect the analog data into an array
StartSample = micros();
for( int xpos = 0;
xpos < 240; xpos ++) { Sample[ xpos] = analogRead(A0)*5/102;
delayMicroseconds(dTime);
}
EndSample = micros();
// Display the collected analog data from array
for( int xpos = 0; xpos < 239;
xpos ++)
{
// Erase previous display
myGLCD.setColor( 0, 0, 0);
myGLCD.drawLine (xpos + 1, 255-OldSample[ xpos + 1]* vsens-hpos, xpos + 2, 255-OldSample[ xpos + 2]* vsens-hpos);
if (xpos == 0) myGLCD.drawLine (xpos + 1, 1, xpos + 1, 239);
// Draw the new data
myGLCD.setColor (255, 255, 255);
myGLCD.drawLine (xpos, 255-Sample[ xpos]* vsens-hpos, xpos + 1, 255-Sample[ xpos + 1]* vsens-hpos);
}
// Determine sample voltage peak to peak
Max = Sample[ 100];
Min = Sample[ 100];
for( int xpos = 0;
xpos < 240; xpos ++)
{
OldSample[ xpos] = Sample[ xpos];
if (Sample[ xpos] > Max) Max = Sample[ xpos];
if (Sample[ xpos] < Min) Min = Sample[ xpos];
}
// display the sample time, delay time and trigger level
myGLCD.setBackColor( 0, 0, 255);
myGLCD.setFont( SmallFont);
myGLCD.setBackColor( 0, 0, 255);
myGLCD.print("Delay", 260, 5);
myGLCD.print(" ", 270, 20);
myGLCD.print(itoa ( dTime, buf, 10), 270, 20);
myGLCD.print("Trig.", 260, 60);
myGLCD.print(" ", 270, 75);
myGLCD.print(itoa( Trigger, buf, 10), 270, 75);
myGLCD.print("H Pos.", 260, 120);
myGLCD.print( itoa( hpos, buf, 10), 270, 135);
//myGLCD.setBackColor( 0, 0, 0);
SampleTime =( EndSample-StartSample)/1000;
myGLCD.print("Sec.", 205, 210);
myGLCD.print(" ", 280, 30);
myGLCD.print(itoa( SampleTime, buf, 10), 205, 220);
// Range of 0 to 64 * 78 = 4992 mV
SampleSize =( Max-Min)*78;
myGLCD.print("mVolt", 5, 210);
myGLCD.print( itoa( SampleSize, buf, 10),5, 220);
myGLCD.print(itoa( analogRead(A0)*4.15/10.23, buf, 10),110 ,220);
}}
//-------------------------END PROGRAM
上图，作者用lm317和555做的一个信号源。
另外，热烈祝贺我家猫成功逮到一只麻雀，通常壁虎是它的猎物，只逮到过一只老鼠，但鼠患已绝。
我更希望的是它能对付苍蝇蚊子。
