fixed minor bugs

exercises/01_arduino/blink/src/main.cpp

@@ -4,7 +4,7 @@ long randNumber;
 
 void setup() {
   Serial.begin(9600);
-  pinMode(D4, OUTPUT); // NodeMCU: D4, Lolin32: D5?
+  pinMode(D4, OUTPUT); // NodeMCU: D4, Lolin32: LED_BUILTIN
   randomSeed(analogRead(0));
 }
 

exercises/01_arduino/screen/.vscode/settings.json

@@ -1,6 +1,6 @@
 {
   "terminal.integrated.env.linux": {
-    "PATH": "/home/mtyers/.platformio/penv/bin:/home/mtyers/.platformio/penv:/home/mtyers/.nvm/versions/node/v10.8.0/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin",
+    "PATH": "/home/mtyers/.platformio/penv/bin:/home/mtyers/.platformio/penv:/home/mtyers/.platformio/penv/bin:/home/mtyers/.platformio/penv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin",
     "PLATFORMIO_CALLER": "vscode"
   }
 }

exercises/01_arduino/screen/include/readme.txt

@@ -0,0 +1,39 @@
+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the usual convention is to give header files names that end with `.h'.
+It is most portable to use only letters, digits, dashes, and underscores in
+header file names, and at most one dot.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html

exercises/01_arduino/screen/platformio.ini

@@ -13,8 +13,8 @@ platform = espressif32
 board = lolin32
 framework = arduino
 ; upload_port = /dev/ttyUSB0
-upload_speed = 14400 ; 9600 14400 19200 28800 38400 57600 115200
+upload_speed = 9600 ; 9600 14400 19200 28800 38400 57600 115200
+upload_protocol = esptool
 
 lib_deps =
   ESP8266_SSD1306
-  Adafruit_Sensor