Fixed USB code in demo sketch

Author: cpp-tutor

README.md

@@ -89,7 +89,7 @@ animate(20);
 
 Note: The Arduino_H7_Video library uses some shared SDRAM for the framebuffer, and `SDRAM.begin();` should **not** be called after initializing the display.
 
-Scripts stored on USB flash devices plugged into the USB port on the Giga can be loaded with `load "script.lox"` at the prompt (some issues with this, currently).
+Scripts stored on USB flash devices plugged into the USB port on the Giga (or via an OTG cable on Portenta H7) can be loaded with `load "script.lox"` at the prompt (any file extension can be used).
 
 ## Adding Functions
 
@@ -150,7 +150,7 @@ int Serial_vfprintf(FILE *dummy, const char *fmt, va_list args);
 #endif
 ```
 
-5. Create a script which defines these two functions, and includes the necessary C headers (as a minimum). Here is a possible outline:
+5. Create a script which defines these three functions, and includes the necessary C headers (as a minimum). Here is a possible outline:
 
 ```ino
 extern "C" {

examples/clox_gfx_demo/clox_gfx_demo.ino

@@ -33,6 +33,9 @@ Arduino_H7_Video Display(1024, 768, USBCVideo);
 
 USBHostMSD msd;
 mbed::FATFileSystem usb("usb");
+#if ( defined(ARDUINO_PORTENTA_H7_M7) && defined(ARDUINO_ARCH_MBED) )
+mbed::DigitalOut otg(PB_14, 0);
+#endif
 #endif
 
 #if CLOX_WEB_CONSOLE
@@ -117,7 +120,7 @@ void loop() {
     line = "";
     char ch = '\0';
     while (ch != '\n') {
-      if (Serial.available()) {
+      if (Serial.available() > 0) {
         ch = Serial.read();
         line += ch;
       }
@@ -154,7 +157,10 @@ void loop() {
 
   digitalWrite(LEDB, LOW);
   if (line.startsWith("load")) {
-    String filename = line.substring(line.indexOf('\"'), line.lastIndexOf('\"'));
+    String filename;
+    if (line.indexOf('\"') != line.lastIndexOf('\"')) {
+      filename = line.substring(line.indexOf('\"') + 1, line.lastIndexOf('\"'));
+    }
     if (filename.length()) {
       String program = readFile(filename);
       if (program.length()) {
@@ -172,7 +178,14 @@ void loop() {
 }
 
 String readFile(String filename) {
+  String fileData;
 #if CLOX_USB_HOST
+  Serial_printf("Waiting for USB device...\n");
+  long until = millis() + 10 * 1000;
+  while (!msd.connected() && (until > millis())) {
+    msd.connect();
+    delay(3000);
+  }
   Serial_printf("Mounting USB device...\n");
   int err = usb.mount(&msd);
   if (err) {
@@ -181,23 +194,24 @@ String readFile(String filename) {
   else {
     filename = String("/usb/") + filename;
     FILE *f = fopen(filename.c_str(), "r+");
-    String fileData;
-    char buf[256];
     if (f) {
+      char buf[256];
       while (fgets(buf, 256, f) != NULL) {
         fileData += String(buf);
       }
       fclose(f);
-      return fileData;
     }
     else {
-      Serial_printf("Error reading file: %s\n", filename);
+      Serial_printf("Error reading file: %s\n", filename.c_str());
+    }
+    if (!usb.unmount()) {
+      Serial_printf("USB device dismounted.\n");
     }
   }
 #else
   Serial_printf("Error: USB support not available.\n");
 #endif
-  return "";
+  return fileData;
 }
 
 #if CLOX_WEB_CONSOLE
@@ -206,7 +220,7 @@ int poll_webserver(unsigned long poll_time) {
   while (millis() < until) {
     WiFiClient webclient = webserver.available();
     if (webclient) {
-      boolean currentLineIsBlank = true;
+      bool currentLineIsBlank = true;
       while (webclient.connected()) {
         if (webclient.available()) {
           char c = webclient.read();

library.properties

@@ -1,5 +1,5 @@
 name=clox_gfx
-version=0.0.2
+version=0.0.3
 author=Richard Spencer <cpptutor@outlook.com>
 maintainer=Richard Spencer <cpptutor@outlook.com>
 sentence=Port of the Lox interpreted programming language to Arduino