Initial commit

libraries/GxEPD2/examples/GxEPD2_Spiffs_Loader/GxEPD2_Spiffs_Loader.ino

@@ -0,0 +1,401 @@
+// GxEPD2_Spiffs_Loader : Display Library example for SPI e-paper panels from Dalian Good Display and boards from Waveshare.
+// Requires HW SPI and Adafruit_GFX. Caution: the e-paper panels require 3.3V supply AND data lines!
+//
+// Display Library based on Demo Example from Good Display: https://www.good-display.com/companyfile/32/
+//
+// Author: Jean-Marc Zingg
+//
+// Version: see library.properties
+//
+// Library: https://github.com/ZinggJM/GxEPD2
+
+// Supporting Arduino Forum Topics (closed, read only):
+// Good Display ePaper for Arduino: https://forum.arduino.cc/t/good-display-epaper-for-arduino/419657
+// Waveshare e-paper displays with SPI: https://forum.arduino.cc/t/waveshare-e-paper-displays-with-spi/467865
+//
+// Add new topics in https://forum.arduino.cc/c/using-arduino/displays/23 for new questions and issues
+
+#if defined(ESP32)
+#include "SPIFFS.h"
+// set formatOnFail = true for initial format of ESP32 SPIFFS (e.g. if error occured)
+const bool formatOnFail = false;
+#endif
+
+#include <FS.h>
+
+#if defined (ESP8266)
+#include <LittleFS.h>
+#include <ESP8266WiFi.h>
+#endif
+
+#include <WiFiClient.h>
+#include <WiFiClientSecure.h>
+
+const char* ssid     = "........";
+const char* password = "........";
+const int httpPort  = 80;
+const int httpsPort = 443;
+
+// note: the certificates have been moved to a separate header file, as R"CERT( destroys IDE Auto Format capability
+
+#include "GxEPD2_github_raw_certs.h"
+
+const char* certificate_rawcontent = github_io_pem;  // ok, should work until Fri, 14 Mar 2025 23:59:59 GMT
+
+const char* host_rawcontent   = "raw.githubusercontent.com";
+const char* path_rawcontent   = "/ZinggJM/GxEPD2/master/extras/bitmaps/";
+const char* path_workcontent  = "/ZinggJM/GxEPD2/work_in_progress/extras/bitmaps/";
+const char* path_prenticedavid   = "/prenticedavid/MCUFRIEND_kbv/master/extras/bitmaps/";
+const char* path_waveshare_c  = "/waveshare/e-Paper/master/RaspberryPi_JetsonNano/c/pic/";
+const char* path_waveshare_py = "/waveshare/e-Paper/master/RaspberryPi_JetsonNano/python/pic/";
+const char* fp_rawcontent     = "97:D8:C5:70:0F:12:24:6C:88:BC:FA:06:7E:8C:A7:4D:A8:62:67:28"; // SHA-1 as of 12.04.2024
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println("GxEPD2_Spiffs_Loader");
+
+#ifdef RE_INIT_NEEDED
+  WiFi.persistent(true);
+  WiFi.mode(WIFI_STA); // switch off AP
+  WiFi.setAutoConnect(true);
+  WiFi.setAutoReconnect(true);
+  WiFi.disconnect();
+#endif
+
+  if (!WiFi.getAutoConnect() || ( WiFi.getMode() != WIFI_STA) || ((WiFi.SSID() != ssid) && String(ssid) != "........"))
+  {
+    Serial.println();
+    Serial.print("WiFi.getAutoConnect()=");
+    Serial.println(WiFi.getAutoConnect());
+    Serial.print("WiFi.SSID()=");
+    Serial.println(WiFi.SSID());
+    WiFi.mode(WIFI_STA); // switch off AP
+    Serial.print("Connecting to ");
+    Serial.println(ssid);
+    WiFi.begin(ssid, password);
+  }
+  int ConnectTimeout = 30; // 15 seconds
+  while (WiFi.status() != WL_CONNECTED)
+  {
+    delay(500);
+    Serial.print(".");
+    Serial.print(WiFi.status());
+    if (--ConnectTimeout <= 0)
+    {
+      Serial.println();
+      Serial.println("WiFi connect timeout");
+      return;
+    }
+  }
+  Serial.println();
+  Serial.println("WiFi connected");
+
+  // Print the IP address
+  Serial.println(WiFi.localIP());
+
+  setClock();
+
+#if defined(ESP32)
+  SPIFFS.begin(formatOnFail);
+  Serial.println("SPIFFS started");
+#else
+  LittleFS.begin();
+  Serial.println("LittleFS started");
+#endif
+  listFiles();
+  //deleteFiles();
+  downloadBitmaps_200x200();
+  downloadBitmaps_other();
+  //downloadBitmaps_test();
+  listFiles();
+}
+
+void loop()
+{
+}
+
+void downloadFile_HTTPS(const char* host, const char* path, const char* filename, const char* fingerprint, const char* target, const char* certificate = certificate_rawcontent);
+
+void downloadBitmaps_200x200()
+{
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "logo200x200.bmp", fp_rawcontent, "logo200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "first200x200.bmp", fp_rawcontent, "first200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "second200x200.bmp", fp_rawcontent, "second200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "third200x200.bmp", fp_rawcontent, "third200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "fourth200x200.bmp", fp_rawcontent, "fourth200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "fifth200x200.bmp", fp_rawcontent, "fifth200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "sixth200x200.bmp", fp_rawcontent, "sixth200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "seventh200x200.bmp", fp_rawcontent, "seventh200x200.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "eighth200x200.bmp", fp_rawcontent, "eighth200x200.bmp");
+}
+
+void downloadBitmaps_other()
+{
+  downloadFile_HTTP("www.squix.org", "/blog/wunderground/", "chanceflurries.bmp", "chanceflurries.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "betty_1.bmp", fp_rawcontent, "betty_1.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "betty_4.bmp", fp_rawcontent, "betty_4.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "marilyn_240x240x8.bmp", fp_rawcontent, "marilyn_240x240x8.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "miniwoof.bmp", fp_rawcontent, "miniwoof.bmp");
+  //downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "test.bmp", fp_rawcontent, "test.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "tiger.bmp", fp_rawcontent, "tiger.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "tiger_178x160x4.bmp", fp_rawcontent, "tiger_178x160x4.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "tiger_240x317x4.bmp", fp_rawcontent, "tiger_240x317x4.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "tiger_320x200x24.bmp", fp_rawcontent, "tiger_320x200x24.bmp");
+  //downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "tiger16T.bmp", fp_rawcontent, "tiger16T.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_prenticedavid, "woof.bmp", fp_rawcontent, "woof.bmp");
+}
+
+void downloadBitmaps_test()
+{
+  //downloadFile_HTTPS(host_rawcontent, path_workcontent, "z0gs/screenshot.bmp", fp_rawcontent, "screenshot.bmp"); return;
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "output5.bmp", fp_rawcontent, "output5.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "output6.bmp", fp_rawcontent, "output6.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_1.bmp", fp_rawcontent, "tractor_1.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_4.bmp", fp_rawcontent, "tractor_4.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_8.bmp", fp_rawcontent, "tractor_8.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_11.bmp", fp_rawcontent, "tractor_11.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_44.bmp", fp_rawcontent, "tractor_44.bmp");
+  downloadFile_HTTPS(host_rawcontent, path_rawcontent, "tractor_88.bmp", fp_rawcontent, "tractor_88.bmp");
+}
+
+void deleteFiles()
+{
+#if defined(ESP32)
+  SPIFFS.remove("logo200x200.bmp");
+  SPIFFS.remove("first200x200.bmp");
+  SPIFFS.remove("second200x200.bmp");
+  SPIFFS.remove("third200x200.bmp");
+  SPIFFS.remove("fourth200x200.bmp");
+  SPIFFS.remove("fifth200x200.bmp");
+  SPIFFS.remove("sixth200x200.bmp");
+  SPIFFS.remove("seventh200x200.bmp");
+  SPIFFS.remove("eighth200x200.bmp");
+  SPIFFS.remove("chanceflurries.bmp");
+  SPIFFS.remove("betty_1.bmp");
+  SPIFFS.remove("betty_4.bmp");
+  SPIFFS.remove("marilyn_240x240x8.bmp");
+  SPIFFS.remove("miniwoof.bmp");
+  SPIFFS.remove("test.bmp");
+  SPIFFS.remove("tiger.bmp");
+  SPIFFS.remove("tiger_178x160x4.bmp");
+  SPIFFS.remove("tiger_240x317x4.bmp");
+  SPIFFS.remove("tiger_320x200x24.bmp");
+  SPIFFS.remove("tiger16T.bmp");
+  SPIFFS.remove("woof.bmp");
+#else
+  LittleFS.remove("logo200x200.bmp");
+  LittleFS.remove("first200x200.bmp");
+  LittleFS.remove("second200x200.bmp");
+  LittleFS.remove("third200x200.bmp");
+  LittleFS.remove("fourth200x200.bmp");
+  LittleFS.remove("fifth200x200.bmp");
+  LittleFS.remove("sixth200x200.bmp");
+  LittleFS.remove("seventh200x200.bmp");
+  LittleFS.remove("eighth200x200.bmp");
+  LittleFS.remove("chanceflurries.bmp");
+  LittleFS.remove("betty_1.bmp");
+  LittleFS.remove("betty_4.bmp");
+  LittleFS.remove("marilyn_240x240x8.bmp");
+  LittleFS.remove("miniwoof.bmp");
+  LittleFS.remove("test.bmp");
+  LittleFS.remove("tiger.bmp");
+  LittleFS.remove("tiger_178x160x4.bmp");
+  LittleFS.remove("tiger_240x317x4.bmp");
+  LittleFS.remove("tiger_320x200x24.bmp");
+  LittleFS.remove("tiger16T.bmp");
+  LittleFS.remove("woof.bmp");
+#endif
+}
+
+void downloadFile_HTTP(const char* host, const char* path, const char* filename, const char* target)
+{
+  WiFiClient client;
+  Serial.print("connecting to ");
+  Serial.println(host);
+  if (!client.connect(host, httpPort))
+  {
+    Serial.println("connection failed");
+    return;
+  }
+  Serial.print("requesting URL: ");
+  Serial.println(String("http://") + host + path + filename);
+  client.print(String("GET ") + path + filename + " HTTP/1.1\r\n" +
+               "Host: " + host + "\r\n" +
+               "User-Agent: GxEPD2_Spiffs_Loader\r\n" +
+               "Connection: close\r\n\r\n");
+  Serial.println("request sent");
+  bool ok = false;
+  while (client.connected() || client.available())
+  {
+    String line = client.readStringUntil('\n');
+    if (!ok)
+    {
+      ok = line.startsWith("HTTP/1.1 200 OK");
+      if (ok) Serial.println(line);
+      //if (!ok) Serial.println(line);
+    }
+    if (!ok) Serial.println(line);
+    //Serial.println(line);
+    if (line == "\r")
+    {
+      Serial.println("headers received");
+      break;
+    }
+  }
+  if (!ok) return;
+  uint8_t buffer[512];
+#if defined(ESP8266)
+  client.peekBytes(buffer, 2);
+  Serial.write(buffer[0]); Serial.write(buffer[1]); Serial.println();
+#endif
+  size_t total = 0;
+#if defined(ESP32)
+  fs::File file = SPIFFS.open(String("/") + target, "w+");
+#else
+  fs::File file = LittleFS.open(target, "w+");
+#endif
+  if (!file)
+  {
+    Serial.print(target); Serial.println(" open failed");
+    return;
+  }
+  while (client.connected() || client.available())
+  {
+    size_t available = client.available();
+    size_t fetch = available <= sizeof(buffer) ? available : sizeof(buffer);
+    if (fetch > 0)
+    {
+      size_t got = client.read(buffer, fetch);
+      file.write(buffer, got);
+      total += got;
+    }
+    delay(1); // yield();
+  }
+  file.close();
+  Serial.print("done, "); Serial.print(total); Serial.println(" bytes transferred");
+}
+
+void downloadFile_HTTPS(const char* host, const char* path, const char* filename, const char* fingerprint, const char* target, const char* certificate)
+{
+  // Use WiFiClientSecure class to create TLS connection
+#if defined (ESP8266)
+  BearSSL::WiFiClientSecure client;
+  BearSSL::X509List cert(certificate ? certificate : certificate_rawcontent);
+#else
+  WiFiClientSecure client;
+#endif
+  Serial.println(); Serial.print("downloading file \""); Serial.print(filename);  Serial.println("\"");
+  Serial.print("connecting to "); Serial.println(host);
+#if defined (ESP8266)
+  client.setBufferSizes(4096, 4096); // required
+  //client.setBufferSizes(8192, 4096); // may help for some sites
+  if (certificate) client.setTrustAnchors(&cert);
+  else if (fingerprint) client.setFingerprint(fingerprint);
+  else client.setInsecure();
+#elif defined (ESP32)
+  if (certificate) client.setCACert(certificate);
+#endif
+  if (!client.connect(host, httpsPort))
+  {
+    Serial.println("connection failed");
+    return;
+  }
+  Serial.print("requesting URL: ");
+  Serial.println(String("https://") + host + path + filename);
+  client.print(String("GET ") + path + filename + " HTTP/1.1\r\n" +
+               "Host: " + host + "\r\n" +
+               "User-Agent: GxEPD2_Spiffs_Loader\r\n" +
+               "Connection: close\r\n\r\n");
+  Serial.println("request sent");
+  bool ok = false;
+  while (client.connected() || client.available())
+  {
+    String line = client.readStringUntil('\n');
+    if (!ok)
+    {
+      ok = line.startsWith("HTTP/1.1 200 OK");
+      if (ok) Serial.println(line);
+      //if (!ok) Serial.println(line);
+    }
+    if (!ok) Serial.println(line);
+    //Serial.println(line);
+    if (line == "\r")
+    {
+      Serial.println("headers received");
+      break;
+    }
+  }
+  if (!ok) return;
+  uint8_t buffer[512];
+#if defined(ESP8266)
+  client.peekBytes(buffer, 2);
+  Serial.write(buffer[0]); Serial.write(buffer[1]); Serial.println();
+#endif
+  size_t total = 0;
+#if defined(ESP32)
+  fs::File file = SPIFFS.open(String("/") + target, "w+");
+#else
+  fs::File file = LittleFS.open(target, "w+");
+#endif
+  if (!file)
+  {
+    Serial.print(target); Serial.println(" open failed");
+    return;
+  }
+  while (client.connected() || client.available())
+  {
+    // this doesn't work as expected, but it helps for long downloads
+    int32_t start = millis();
+    for (int16_t t = 0, dly = 50; t < 20; t++, dly += 50)
+    {
+      if (!(client.connected() || client.available())) break;
+      if (client.available()) break; // read would not recover after having returned 0
+      delay(dly);
+    }
+    if (!(client.connected() || client.available())) break;
+    int32_t elapsed = millis() - start;
+    if (elapsed > 250)
+    {
+      Serial.print("waited for available "); Serial.print(millis() - start); Serial.print(" ms @ "); Serial.println(total);
+    }
+    size_t available = client.available();
+    if (0 == available)
+    {
+      Serial.print("download error: timeout on available() after "); Serial.print(total); Serial.println(" bytes");
+      break; // don't hang forever
+    }
+    size_t fetch = available <= sizeof(buffer) ? available : sizeof(buffer);
+    if (fetch > 0)
+    {
+      size_t got = client.read(buffer, fetch);
+      file.write(buffer, got);
+      total += got;
+    }
+    delay(1); // yield();
+    if (total > 30000) delay(250); // helps for long downloads
+  }
+  file.close();
+  Serial.print("done, "); Serial.print(total); Serial.println(" bytes transferred");
+}
+
+// Set time via NTP, as required for x.509 validation
+void setClock()
+{
+  configTime(3 * 3600, 0, "pool.ntp.org", "time.nist.gov");
+
+  Serial.print("Waiting for NTP time sync: ");
+  time_t now = time(nullptr);
+  while (now < 8 * 3600 * 2)
+  {
+    delay(500);
+    Serial.print(".");
+    now = time(nullptr);
+  }
+  Serial.println("");
+  struct tm timeinfo;
+  gmtime_r(&now, &timeinfo);
+  Serial.print("Current time: ");
+  Serial.print(asctime(&timeinfo));
+}

libraries/GxEPD2/examples/GxEPD2_Spiffs_Loader/GxEPD2_github_raw_certs.h

@@ -0,0 +1,184 @@
+// how to find the certificate was not easy. finally I found it using Mozilla Firefox.
+// opened one of the bitmaps, e.g. https://raw.githubusercontent.com/ZinggJM/GxEPD2/master/extras/bitmaps/logo200x200.bmp
+// clicked the lock symbol, Connection secure clicked >, show connection details, clicked More Information, clicked View Certificate, clicked Download PEM (cert),
+// Opened the .pem file and copied the pem into R"CERT(...)CERT"; strings.
+// for https://raw.githubusercontent.com the pem works on ESP8266 and ESP32, if time is set from ntp.
+// but using a root certificate would preferred, as its validity may be longer. But this failed now.
+
+const char github_io_pem [] PROGMEM = R"CERT(
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+)CERT";
+
+// 12:04.2024: the following no longer works, needs further investigation
+// **********************************************************************
+
+// http://cacerts.digicert.com/DigiCertTLSRSASHA2562020CA1-1.crt
+// CN: DigiCert TLS RSA SHA256 2020 CA1 => name: DigiCert_TLS_RSA_SHA256_2020_CA1
+// not valid before: 2021-04-14 00:00:00
+// not valid after:  2031-04-13 23:59:59
+const char cert_DigiCert_TLS_RSA_SHA256_2020_CA1 [] PROGMEM = R"CERT(
+-----BEGIN CERTIFICATE-----
+MIIEvjCCA6agAwIBAgIQBtjZBNVYQ0b2ii+nVCJ+xDANBgkqhkiG9w0BAQsFADBh
+MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3
+d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBD
+QTAeFw0yMTA0MTQwMDAwMDBaFw0zMTA0MTMyMzU5NTlaME8xCzAJBgNVBAYTAlVT
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+A7sKPPcw7+uvTPyLNhBzPvOk
+-----END CERTIFICATE-----
+  )CERT";
+
+// how to find the certificate was not easy. finally I found it using Mozilla Firefox.
+// opened one of the bitmaps, e.g. https://raw.githubusercontent.com/ZinggJM/GxEPD2/master/extras/bitmaps/logo200x200.bmp
+// clicked the lock symbol, Connection secure clicked >, show connection details, clicked More Information, clicked View Certificate, clicked Download PEM (chain),
+// Opened the .pem file and copied the pems into R"CERT(...)CERT"; strings.
+// for https://raw.githubusercontent.com all three pems work on ESP8266 and ESP32, if time is set from ntp.
+// but using a root certificate is preferred, as its validity may be longer.
+
+// https://raw.githubusercontent.com
+// issued by DigiCert Inc : DigiCert TLS RSA SHA256 2020 CA1
+// not valid before: Fri, 15 Mar 2024 00:00:00 GMT
+// not valid after:  Fri, 14 Mar 2025 23:59:59 GMT
+const char github_io_chain_pem_first [] PROGMEM = R"CERT(
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
+)CERT";
+const char github_io_chain_pem_second [] PROGMEM = R"CERT(
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
+)CERT";
+const char github_io_chain_pem_third [] PROGMEM = R"CERT(
+-----BEGIN CERTIFICATE-----
+MIIDjjCCAnagAwIBAgIQAzrx5qcRqaC7KGSxHQn65TANBgkqhkiG9w0BAQsFADBh
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+MrY=
+-----END CERTIFICATE-----
+)CERT";

libraries/GxEPD2/examples/GxEPD2_Spiffs_Loader/SPIFFS_Support.ino

@@ -0,0 +1,94 @@
+#if defined(ESP32)
+
+#include "FS.h"
+
+void listDir(fs::FS &fs, const char * dirname, uint8_t levels) {
+  Serial.printf("Listing directory: %s\r\n", dirname);
+
+  File root = fs.open(dirname);
+  if (!root) {
+    Serial.println("- failed to open directory");
+    return;
+  }
+  if (!root.isDirectory()) {
+    Serial.println(" - not a directory");
+    return;
+  }
+
+  File file = root.openNextFile();
+  while (file) {
+    if (file.isDirectory()) {
+      Serial.print("  DIR : ");
+      Serial.println(file.name());
+      if (levels) {
+        listDir(fs, file.name(), levels - 1);
+      }
+    } else {
+      Serial.print("  FILE: ");
+      Serial.print(file.name());
+      Serial.print("\tSIZE: ");
+      Serial.println(file.size());
+    }
+    file = root.openNextFile();
+  }
+}
+
+void listFiles()
+{
+  listDir(SPIFFS, "/", 0);
+}
+
+#elif defined(ESP8266)
+
+#include <FS.h>
+#include <LittleFS.h>
+
+/*====================================================================================
+  This sketch contains support functions for the ESP6266 LittleFS filing system
+
+  Created by Bodmer 15th Jan 2017
+  ==================================================================================*/
+
+//====================================================================================
+//                 Print a LittleFS directory list (root directory)
+//====================================================================================
+
+void listFiles(void) {
+  Serial.println();
+  Serial.println("LittleFS files found:");
+
+  fs::Dir dir = LittleFS.openDir(""); // Root directory
+  String  line = "=====================================";
+  uint32_t totalBytes = 0;
+
+  Serial.println(line);
+  Serial.println("  File name               Size");
+  Serial.println(line);
+
+  while (dir.next()) {
+    String fileName = dir.fileName();
+    Serial.print(fileName);
+    int spaces = 25 - fileName.length(); // Tabulate nicely
+    while (spaces--) Serial.print(" ");
+    fs::File f = dir.openFile("r");
+    Serial.print(f.size()); Serial.println(" bytes");
+    totalBytes += f.size();
+  }
+  Serial.println(); Serial.print("Total = ");
+  int spaces = 25 - 8; // Tabulate nicely
+  while (spaces--) Serial.print(" ");
+  Serial.print(totalBytes); Serial.println(" bytes");
+
+  Serial.println(line);
+  Serial.println();
+  delay(1000);
+}
+//====================================================================================
+
+#else
+
+void listFiles()
+{
+  Serial.println("LittleFS listFiles() not implemented");
+}
+#endif