The code run on NodeMCU-32S (ESP32 in Arduino framework) capture analog input in background base on timer interrupt, display on SPI ILI9341 screen graphically.
The timer interrupt is prepared in setup(), refer to Arduino IDE Examples > ESP32 > Timer > RepeatTimer.
bfr[][] is a 2x300 double buffer to store captured analog data. When one page (300 elements) is filled in interrupt service routine, it will switch to fill the another page and set bfr_filled flag to display the filled page in main loop(). Such that the main loop have to finish display within one page filled, 300 x sampling interval.
ESP32_AIN_TmrInt_20210112b.ino
#include "SPI.h"
#include "TFT_eSPI.h"
#define TFT_GREY 0x7BEF
TFT_eSPI myGLCD = TFT_eSPI();
#define FRAME_TOPX 10
#define FRAME_TOPY 5
#define FRAME_WIDTH 300
#define FRAME_HEIGHT 200
#define FRAME_BOTTOMY FRAME_TOPY + FRAME_HEIGHT
#define LAMP_PLOTTING_X FRAME_TOPX+290
#define LAMP_PLOTTING_Y FRAME_BOTTOMY+10
#define LAMP_PLOTTING_R 5
#define NO_OF_BFR_PAGE 2
#define NO_OF_BFR_ELE 300
unsigned int bfr[NO_OF_BFR_PAGE][NO_OF_BFR_ELE];
volatile int bfr_page;
volatile int bfr_idx;
volatile bool bfr_filled;
volatile int bfr_filled_page;
volatile bool bfr_run = false;
volatile int updateDot = -1;
volatile unsigned long prvSamplingTime;
#define PrgressDot_X FRAME_TOPX
#define PrgressDot_Y FRAME_BOTTOMY+4
#define PinAnalogIn 36
unsigned long previousTime = 0;
hw_timer_t * timer = NULL;
volatile SemaphoreHandle_t timerSemaphore;
void IRAM_ATTR onTimer(){
toFillBfr();
// Give a semaphore that we can check in the loop
xSemaphoreGiveFromISR(timerSemaphore, NULL);
}
void setup() {
Serial.begin(115200);
myGLCD.init();
myGLCD.setRotation(1);
myGLCD.fillScreen(TFT_BLACK);
delay(500);
myGLCD.fillRect(FRAME_TOPX-1, FRAME_TOPY-1,
FRAME_WIDTH+2, FRAME_HEIGHT+2, TFT_WHITE);
myGLCD.fillRect(FRAME_TOPX, FRAME_TOPY,
FRAME_WIDTH, FRAME_HEIGHT, TFT_GREY);
myGLCD.setTextColor(TFT_WHITE,TFT_BLACK);
myGLCD.drawString("Double Buffer", FRAME_TOPX, FRAME_BOTTOMY+20);
// prepare bfr
bfr_run = false;
bfr_filled = false;
bfr_page = 0;
bfr_idx = 0;
bfr_run = true;
// --- Prepare Timer Intrrupt ---
// Create semaphore to inform us when the timer has fired
timerSemaphore = xSemaphoreCreateBinary();
// Use 1st timer of 4 (counted from zero).
// Set 80 divider for prescaler (see ESP32 Technical Reference Manual for more
// info).
timer = timerBegin(0, 80, true);
// Attach onTimer function to our timer.
timerAttachInterrupt(timer, &onTimer, true);
// Set alarm to call onTimer function every second (value in microseconds).
// Repeat the alarm (third parameter)
timerAlarmWrite(timer, 10000, true); //10ms
//timerAlarmWrite(timer, 1000, true); //1ms
// Start an alarm
timerAlarmEnable(timer);
prvSamplingTime = micros();
// --- End of Prepare Timer Intrrupt ---
Serial.println("\n --- Start ---\n");
Serial.println("CPU Frequency (Mhz): " + String(getCpuFrequencyMhz()));
}
void handle_screen(){
if(bfr_filled){
//unsigned long beforeScreen = micros();
bfr_filled = false;
myGLCD.fillCircle(LAMP_PLOTTING_X, LAMP_PLOTTING_Y, LAMP_PLOTTING_R, TFT_RED);
myGLCD.fillRect(FRAME_TOPX, FRAME_TOPY,
FRAME_WIDTH, FRAME_HEIGHT, TFT_GREY);
int yPrv = bfr[bfr_filled_page][0];
for(int i=1; i<NO_OF_BFR_ELE; i++){
int yCur = bfr[bfr_filled_page][i];
myGLCD.drawLine(FRAME_TOPX+i-1, FRAME_BOTTOMY-yPrv,
FRAME_TOPX+i, FRAME_BOTTOMY-yCur,
TFT_WHITE);
yPrv = yCur;
}
myGLCD.fillCircle(LAMP_PLOTTING_X, LAMP_PLOTTING_Y, LAMP_PLOTTING_R, TFT_GREEN);
myGLCD.drawLine(PrgressDot_X, PrgressDot_Y, PrgressDot_X+299, PrgressDot_Y, TFT_BLACK);
//Serial.println("Fil duration: " + String(micros()-beforeScreen) + " (microsecond)");
}
//to draw alblue line under the graph for indicate the sample progress
if(int x=updateDot){
updateDot = -1;
myGLCD.drawPixel(PrgressDot_X+x, PrgressDot_Y, TFT_BLUE);
}
}
void loop() {
if (xSemaphoreTake(timerSemaphore, 0) == pdTRUE){
handle_screen();
}
}
void toFillBfr(){
//unsigned long beforeFill = micros();
unsigned long int curSamplingTime = micros();
if(bfr_run){
bfr[bfr_page][bfr_idx] = map(analogRead(PinAnalogIn),0, 4096, 0, 200);
updateDot = bfr_idx;
bfr_idx++;
if(bfr_idx >= NO_OF_BFR_ELE){
bfr_filled_page = bfr_page;
bfr_idx=0;
if(bfr_page==0){
bfr_page = 1;
}else{
bfr_page = 0;
}
bfr_filled = true;
}
}
//Send sampling interval to Serial Monitor for evaluation only,
//remove it before finalize.
Serial.println(curSamplingTime - prvSamplingTime);
prvSamplingTime = curSamplingTime;
//Serial.println("Fil duration: " + String(micros()-beforeFill) + " (microsecond)");
}
Exercise run on ESP32 (NodeMCU-32S), Combine the examples of ESP32_SimpleTime and TFT_DIGITAL_CLOCK, get time from ntpServer "pool.ntp.org", and display on 2.4" 320x240 SPI ILI9341 screen in digital clock form.
ESP32_ILI9341_ntp_Clock_Digital_2021-01-10a.ino
/*
* ESP32_ILI9341_ntp_Clock_Digital
*
* Combine the examples of
* Examples > ESP32 > Time > ESP32_SimpleTime and
* Examples > TFT_eSPI > 320 x 240 > TFT_DIGITAL_CLOCK
*
* Get time from ntpServer "pool.ntp.org",
* display on SPI ILI9341 screen in digital clock form.
*
* You have to change ssid/password to match with your wifi network.
* and change gmtOffset_sec to match your timezone.
=========================================================================
Make sure all the display driver and pin comnenctions are correct by
editting the User_Setup.h file in the TFT_eSPI library folder.
#########################################################################
###### DON'T FORGET TO UPDATE THE User_Setup.h FILE IN THE LIBRARY ######
#########################################################################
For using SPI ILI9341 screen on ESP32,
refer Arduino-er: ESP32 + 2.4" 320X240 Display (SPI ILI9341),
using TFT_eSPI, prepare user setup file.
http://arduino-er.blogspot.com/2021/01/esp32-24-320x240-display-spi-ili9341.html
A few colour codes:
code color
0x0000 Black
0xFFFF White
0xBDF7 Light Gray
0x7BEF Dark Gray
0xF800 Red
0xFFE0 Yellow
0xFBE0 Orange
0x79E0 Brown
0x7E0 Green
0x7FF Cyan
0x1F Blue
0xF81F Pink
*/
#include <TFT_eSPI.h> // Hardware-specific library
#include <SPI.h>
#include <WiFi.h>
#include "time.h"
const char* ssid = "ssid";
const char* password = "password";
const char* ntpServer = "pool.ntp.org";
//+8 hr@HongKong
//8 * 60 * 60 = 28800
const long gmtOffset_sec = 28800; //-8hr@Hong Kong
const int daylightOffset_sec = 3600;
#define TFT_GREY 0x5AEB
TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
uint32_t targetTime = 0; // for next 1 second timeout
/* The original example get H, M, S from compile time
static uint8_t conv2d(const char* p); // Forward declaration needed for IDE 1.6.x
uint8_t hh = conv2d(__TIME__), mm = conv2d(__TIME__ + 3),
ss = conv2d(__TIME__ + 6); // Get H, M, S from compile time
*/
/*
* Get H,M, S after ntp server connected,
* will load in printLocalTime()
*/
uint8_t hh,mm,ss;
byte omm = 99, oss = 99;
byte xcolon = 0, xsecs = 0;
unsigned int colour = 0;
void printLocalTime()
{
struct tm timeinfo;
if(!getLocalTime(&timeinfo)){
Serial.println("Failed to obtain time");
return;
}
Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
/* to read elements from getLocalTime(&timeinfo)
* ref:
* http://www.cplusplus.com/reference/ctime/tm/
*/
int time_yday = timeinfo.tm_yday; //days since January 1
int time_wday = timeinfo.tm_wday; //days since Sunday
int time_year = timeinfo.tm_year; // years since 1900
int time_mon = timeinfo.tm_mon; //months since January
int time_mday = timeinfo.tm_mday; //day of the month
int time_hr = timeinfo.tm_hour;
int time_min = timeinfo.tm_min;
int time_sec = timeinfo.tm_sec;
Serial.println("tm_yday: " + String(time_yday));
Serial.println("tm_wday: " + String(time_wday));
Serial.println("tm_year: " + String(time_year));
Serial.println("tm_mon: " + String(time_mon));
Serial.println("tm_mday: " + String(time_mday));
Serial.println("tm_hr: " + String(time_hr));
Serial.println("tm_min: " + String(time_min));
Serial.println("tm_sec: " + String(time_sec));
hh = time_hr;
mm = time_min;
ss = time_sec;
}
void setup(void) {
Serial.begin(115200);
/*
* Connect to WiFi, and get time from ntpServer
* To simplify, only once when power-up.
*/
//connect to WiFi
Serial.printf("Connecting to %s ", ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println(" CONNECTED");
//init and get the time
configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
printLocalTime();
//disconnect WiFi as it's no longer needed
WiFi.disconnect(true);
WiFi.mode(WIFI_OFF);
/*
* Prepare for TFT
*/
tft.init();
tft.setRotation(1);
tft.fillScreen(TFT_BLACK);
tft.setTextSize(1);
tft.setTextColor(TFT_YELLOW, TFT_BLACK);
targetTime = millis() + 1000;
}
void loop() {
if (targetTime < millis()) {
// Set next update for 1 second later
targetTime = millis() + 1000;
// Adjust the time values by adding 1 second
ss++; // Advance second
if (ss == 60) { // Check for roll-over
ss = 0; // Reset seconds to zero
omm = mm; // Save last minute time for display update
mm++; // Advance minute
if (mm > 59) { // Check for roll-over
mm = 0;
hh++; // Advance hour
if (hh > 23) { // Check for 24hr roll-over (could roll-over on 13)
hh = 0; // 0 for 24 hour clock, set to 1 for 12 hour clock
}
}
}
// Update digital time
int xpos = 0;
int ypos = 85; // Top left corner ot clock text, about half way down
int ysecs = ypos + 24;
if (omm != mm) { // Redraw hours and minutes time every minute
omm = mm;
// Draw hours and minutes
if (hh < 10) xpos += tft.drawChar('0', xpos, ypos, 8); // Add hours leading zero for 24 hr clock
xpos += tft.drawNumber(hh, xpos, ypos, 8); // Draw hours
xcolon = xpos; // Save colon coord for later to flash on/off later
xpos += tft.drawChar(':', xpos, ypos - 8, 8);
if (mm < 10) xpos += tft.drawChar('0', xpos, ypos, 8); // Add minutes leading zero
xpos += tft.drawNumber(mm, xpos, ypos, 8); // Draw minutes
xsecs = xpos; // Sae seconds 'x' position for later display updates
}
if (oss != ss) { // Redraw seconds time every second
oss = ss;
xpos = xsecs;
if (ss % 2) { // Flash the colons on/off
tft.setTextColor(0x39C4, TFT_BLACK); // Set colour to grey to dim colon
tft.drawChar(':', xcolon, ypos - 8, 8); // Hour:minute colon
xpos += tft.drawChar(':', xsecs, ysecs, 6); // Seconds colon
tft.setTextColor(TFT_YELLOW, TFT_BLACK); // Set colour back to yellow
}
else {
tft.drawChar(':', xcolon, ypos - 8, 8); // Hour:minute colon
xpos += tft.drawChar(':', xsecs, ysecs, 6); // Seconds colon
}
//Draw seconds
if (ss < 10) xpos += tft.drawChar('0', xpos, ysecs, 6); // Add leading zero
tft.drawNumber(ss, xpos, ysecs, 6); // Draw seconds
}
}
}
/*
// Function to extract numbers from compile time string
static uint8_t conv2d(const char* p) {
uint8_t v = 0;
if ('0' <= *p && *p <= '9')
v = *p - '0';
return 10 * v + *++p - '0';
}
*/
Reading the TFT_eSPI GitHub page, if you update TFT_eSPI then it will over-write your setups if they are kept within the TFT_eSPI folder. It's suggested to create a new folder in your Arduino library folder called "TFT_eSPI_Setups". You then place your custom setup.h files in there. After an upgrade simply edit the User_Setup_Select.h file to point to your custom setup file.
Here is how to prepare my custom setup file for using SPI ILI9341 on ESP32 (NodeMCU-32S).
- Create a new folder in your Arduino library folder called "TFT_eSPI_Setups"
- Copy default User_Setup.h (checked it match with using SPI ILI9341) to "TFT_eSPI_Setups" folder, rename it if you want.
- Edit the User_Setup_Select.h file to point to the custom setup file.
- Edit the custom user setup file:
ILI9341_DRIVER is selected by default, keep it no change.
Comment and un-comment the pin assignment code as shown:
Connect the display module to ESP32 dev. board accordingly.
Setup Library in Arduino IDE:
Menu > Sketch > Include Library > Manager Libraries...
Search and install TFT_eSPI
Then have to edit User_Setup.h to fix your circuit.
- Confirm ILI9341_DRIVER is defined
- comment the original define of:
TFT_CS, TFT_DC and TFT_RST.
- un-comment the pin define under "For ESP32 Dev board (only tested with ILI9341 display)"
TFT_MISO, TFT_MOSI 23, TFT_SCLK, TFT_CS, TFT_DC and TFT_RST.
Then, you can try any example under TFT_eSPI.
Using TFT_eSPI, if you load a new copy of TFT_eSPI then it will over-write your setups if they are kept within the TFT_eSPI folder. It's suggested to create a new folder in your Arduino library folder called "TFT_eSPI_Setups". You then place your custom setup.h files in there. After an upgrade simply edit the User_Setup_Select.h file to point to your custom setup file.
