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ESPUI/examples/completeExample/completeExample.cpp

524 lines
23 KiB
C++

/**
* @file completeExample.cpp
* @author Ian Gray @iangray1000
*
* This is an example GUI to show off all of the features of ESPUI.
* This can be built using the Arduino IDE, or PlatformIO.
*
* ---------------------------------------------------------------------------------------
* If you just want to see examples of the ESPUI code, jump down to the setUpUI() function
* ---------------------------------------------------------------------------------------
*
* When this program boots, it will load an SSID and password from the EEPROM.
* The SSID is a null-terminated C string stored at EEPROM addresses 0-31
* The password is a null-terminated C string stored at EEPROM addresses 32-95.
* If these credentials do not work for some reason, the ESP will create an Access
* Point wifi with the SSID HOSTNAME (defined below). You can then connect and use
* the controls on the "Wifi Credentials" tab to store credentials into the EEPROM.
*
*/
#include <Arduino.h>
#include <EEPROM.h>
#include <ESPUI.h>
#if defined(ESP32)
#include <WiFi.h>
#include <ESPmDNS.h>
#else
#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>
#endif
//Settings
#define SLOW_BOOT 0
#define HOSTNAME "ESPUITest"
#define FORCE_USE_HOTSPOT 0
//Function Prototypes
void connectWifi();
void setUpUI();
void enterWifiDetailsCallback(Control *sender, int type);
void textCallback(Control *sender, int type);
void generalCallback(Control *sender, int type);
void scrambleCallback(Control *sender, int type);
void styleCallback(Control *sender, int type);
void updateCallback(Control *sender, int type);
void getTimeCallback(Control *sender, int type);
void graphAddCallback(Control *sender, int type);
void graphClearCallback(Control *sender, int type);
void randomString(char *buf, int len);
//UI handles
uint16_t wifi_ssid_text, wifi_pass_text;
uint16_t mainLabel, mainSwitcher, mainSlider, mainText, mainNumber, mainScrambleButton, mainTime;
uint16_t styleButton, styleLabel, styleSwitcher, styleSlider, styleButton2, styleLabel2, styleSlider2;
uint16_t graph;
volatile bool updates = false;
// This is the main function which builds our GUI
void setUpUI() {
//Turn off verbose debugging
ESPUI.setVerbosity(Verbosity::Quiet);
//Make sliders continually report their position as they are being dragged.
ESPUI.sliderContinuous = true;
//This GUI is going to be a tabbed GUI, so we are adding most controls using ESPUI.addControl
//which allows us to set a parent control. If we didn't need tabs we could use the simpler add
//functions like:
// ESPUI.button()
// ESPUI.label()
/*
* Tab: Basic Controls
* This tab contains all the basic ESPUI controls, and shows how to read and update them at runtime.
*-----------------------------------------------------------------------------------------------------------*/
auto maintab = ESPUI.addControl(Tab, "", "Basic controls");
ESPUI.addControl(Separator, "General controls", "", None, maintab);
ESPUI.addControl(Button, "Button", "Button 1", Alizarin, maintab, generalCallback);
mainLabel = ESPUI.addControl(Label, "Label", "Label text", Emerald, maintab, generalCallback);
mainSwitcher = ESPUI.addControl(Switcher, "Switcher", "", Sunflower, maintab, generalCallback);
//Sliders default to being 0 to 100, but if you want different limits you can add a Min and Max control
mainSlider = ESPUI.addControl(Slider, "Slider", "200", Turquoise, maintab, generalCallback);
ESPUI.addControl(Min, "", "10", None, mainSlider);
ESPUI.addControl(Max, "", "400", None, mainSlider);
//These are the values for the selector's options. (Note that they *must* be declared static
//so that the storage is allocated in global memory and not just on the stack of this function.)
static String optionValues[] {"Value 1", "Value 2", "Value 3", "Value 4", "Value 5"};
auto mainselector = ESPUI.addControl(Select, "Selector", "Selector", Wetasphalt, maintab, generalCallback);
for(auto const& v : optionValues) {
ESPUI.addControl(Option, v.c_str(), v, None, mainselector);
}
mainText = ESPUI.addControl(Text, "Text Input", "Initial value", Alizarin, maintab, generalCallback);
//Number inputs also accept Min and Max components, but you should still validate the values.
mainNumber = ESPUI.addControl(Number, "Number Input", "42", Emerald, maintab, generalCallback);
ESPUI.addControl(Min, "", "10", None, mainNumber);
ESPUI.addControl(Max, "", "50", None, mainNumber);
ESPUI.addControl(Separator, "Updates", "", None, maintab);
//This button will update all the updatable controls on this tab to random values
mainScrambleButton = ESPUI.addControl(Button, "Scramble Values", "Scramble Values", Carrot, maintab, scrambleCallback);
ESPUI.addControl(Switcher, "Constant updates", "0", Carrot, maintab, updateCallback);
mainTime = ESPUI.addControl(Time, "", "", None, 0, generalCallback);
ESPUI.addControl(Button, "Get Time", "Get Time", Carrot, maintab, getTimeCallback);
ESPUI.addControl(Separator, "Control Pads", "", None, maintab);
ESPUI.addControl(Pad, "Normal", "", Peterriver, maintab, generalCallback);
ESPUI.addControl(PadWithCenter, "With center", "", Peterriver, maintab, generalCallback);
/*
* Tab: Colours
* This tab shows all the basic colours
*-----------------------------------------------------------------------------------------------------------*/
auto colourtab = ESPUI.addControl(Tab, "", "Colours");
ESPUI.addControl(Button, "Alizarin", "Alizarin", Alizarin, colourtab, generalCallback);
ESPUI.addControl(Button, "Turquoise", "Turquoise", Turquoise, colourtab, generalCallback);
ESPUI.addControl(Button, "Emerald", "Emerald", Emerald, colourtab, generalCallback);
ESPUI.addControl(Button, "Peterriver", "Peterriver", Peterriver, colourtab, generalCallback);
ESPUI.addControl(Button, "Wetasphalt", "Wetasphalt", Wetasphalt, colourtab, generalCallback);
ESPUI.addControl(Button, "Sunflower", "Sunflower", Sunflower, colourtab, generalCallback);
ESPUI.addControl(Button, "Carrot", "Carrot", Carrot, colourtab, generalCallback);
ESPUI.addControl(Button, "Dark", "Dark", Dark, colourtab, generalCallback);
/*
* Tab: Styled controls
* This tab shows off how inline CSS styles can be applied to elements and panels in order
* to customise the look of the UI.
*-----------------------------------------------------------------------------------------------------------*/
auto styletab = ESPUI.addControl(Tab, "", "Styled controls");
styleButton = ESPUI.addControl(Button, "Styled Button", "Button", Alizarin, styletab, generalCallback);
styleLabel = ESPUI.addControl(Label, "Styled Label", "This is a label", Alizarin, styletab, generalCallback);
styleSwitcher = ESPUI.addControl(Switcher, "Styled Switcher", "1", Alizarin, styletab, generalCallback);
styleSlider = ESPUI.addControl(Slider, "Styled Slider", "0", Alizarin, styletab, generalCallback);
//This button will randomise the colours of the above controls to show updating of inline styles
ESPUI.addControl(Button, "Randomise Colours", "Randomise Colours", Sunflower, styletab, styleCallback);
ESPUI.addControl(Separator, "Other styling examples", "", None, styletab);
styleButton2 = ESPUI.addControl(Button, "Styled Button", "Button", Alizarin, styletab, generalCallback);
ESPUI.setPanelStyle(styleButton2, "background: linear-gradient(90deg, rgba(131,58,180,1) 0%, rgba(253,29,29,1) 50%, rgba(252,176,69,1) 100%); border-bottom: #555;");
ESPUI.setElementStyle(styleButton2, "border-radius: 2em; border: 3px solid black; width: 30%; background-color: #8df;");
styleSlider2 = ESPUI.addControl(Slider, "Styled Slider", "0", Dark, styletab, generalCallback);
ESPUI.setElementStyle(styleSlider2, "background: linear-gradient(to right, red, orange, yellow, green, blue);");
styleLabel2 = ESPUI.addControl(Label, "Styled Label", "This is a label", Dark, styletab, generalCallback);
ESPUI.setElementStyle(styleLabel2, "text-shadow: 3px 3px #74b1ff, 6px 6px #c64ad7; font-size: 60px; font-variant-caps: small-caps; background-color: unset; color: #c4f0bb; -webkit-text-stroke: 1px black;");
/*
* Tab: Grouped controls
* This tab shows how multiple control can be grouped into the same panel through the use of the
* parentControl value. This also shows how to add labels to grouped controls, and how to use vertical controls.
*-----------------------------------------------------------------------------------------------------------*/
auto grouptab = ESPUI.addControl(Tab, "", "Grouped controls");
//The parent of this button is a tab, so it will create a new panel with one control.
auto groupbutton = ESPUI.addControl(Button, "Button Group", "Button A", Dark, grouptab, generalCallback);
//However the parent of this button is another control, so therefore no new panel is
//created and the button is added to the existing panel.
ESPUI.addControl(Button, "", "Button B", Alizarin, groupbutton, generalCallback);
ESPUI.addControl(Button, "", "Button C", Alizarin, groupbutton, generalCallback);
//Sliders can be grouped as well
//To label each slider in the group, we are going add additional labels and give them custom CSS styles
//We need this CSS style rule, which will remove the label's background and ensure that it takes up the entire width of the panel
String clearLabelStyle = "background-color: unset; width: 100%;";
//First we add the main slider to create a panel
auto groupsliders = ESPUI.addControl(Slider, "Slider Group", "10", Dark, grouptab, generalCallback);
//Then we add a label and set its style to the clearLabelStyle. Here we've just given it the name "A"
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "A", None, groupsliders), clearLabelStyle);
//We can now continue to add additional sliders and labels
ESPUI.addControl(Slider, "", "20", None, groupsliders, generalCallback);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "B", None, groupsliders), clearLabelStyle);
ESPUI.addControl(Slider, "", "30", None, groupsliders, generalCallback);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "C", None, groupsliders), clearLabelStyle);
//We can also usefully group switchers.
auto groupswitcher = ESPUI.addControl(Switcher, "Switcher Group", "0", Dark, grouptab, generalCallback);
ESPUI.addControl(Switcher, "", "1", Sunflower, groupswitcher, generalCallback);
ESPUI.addControl(Switcher, "", "0", Sunflower, groupswitcher, generalCallback);
ESPUI.addControl(Switcher, "", "1", Sunflower, groupswitcher, generalCallback);
//To label these switchers we need to first go onto a "new line" below the line of switchers
//To do this we add an empty label set to be clear and full width (with our clearLabelStyle)
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "", None, groupswitcher), clearLabelStyle);
//We will now need another label style. This one sets its width to the same as a switcher (and turns off the background)
String switcherLabelStyle = "width: 60px; margin-left: .3rem; margin-right: .3rem; background-color: unset;";
//We can now just add the styled labels.
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "A", None, groupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "B", None, groupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "C", None, groupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "D", None, groupswitcher), switcherLabelStyle);
//You can mix and match different control types, but the results might sometimes
//need additional styling to lay out nicely.
auto grouplabel = ESPUI.addControl(Label, "Mixed Group", "Main label", Dark, grouptab);
auto grouplabel2 = ESPUI.addControl(Label, "", "Secondary label", Emerald, grouplabel);
ESPUI.addControl(Button, "", "Button D", Alizarin, grouplabel, generalCallback);
ESPUI.addControl(Switcher, "", "1", Sunflower, grouplabel, generalCallback);
ESPUI.setElementStyle(grouplabel2, "font-size: x-large; font-family: serif;");
//Some controls can even support vertical orientation, currently Switchers and Sliders
ESPUI.addControl(Separator, "Vertical controls", "", None, grouptab);
auto vertgroupswitcher = ESPUI.addControl(Switcher, "Vertical Switcher Group", "0", Dark, grouptab, generalCallback);
ESPUI.setVertical(vertgroupswitcher);
//On the following lines we wrap the value returned from addControl and send it straight to setVertical
ESPUI.setVertical(ESPUI.addControl(Switcher, "", "0", None, vertgroupswitcher, generalCallback));
ESPUI.setVertical(ESPUI.addControl(Switcher, "", "0", None, vertgroupswitcher, generalCallback));
ESPUI.setVertical(ESPUI.addControl(Switcher, "", "0", None, vertgroupswitcher, generalCallback));
//The mechanism for labelling vertical switchers is the same as we used above for horizontal ones
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "", None, vertgroupswitcher), clearLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "A", None, vertgroupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "B", None, vertgroupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "C", None, vertgroupswitcher), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "D", None, vertgroupswitcher), switcherLabelStyle);
auto vertgroupslider = ESPUI.addControl(Slider, "Vertical Slider Group", "15", Dark, grouptab, generalCallback);
ESPUI.setVertical(vertgroupslider);
ESPUI.setVertical(ESPUI.addControl(Slider, "", "25", None, vertgroupslider, generalCallback));
ESPUI.setVertical(ESPUI.addControl(Slider, "", "35", None, vertgroupslider, generalCallback));
ESPUI.setVertical(ESPUI.addControl(Slider, "", "45", None, vertgroupslider, generalCallback));
//The mechanism for labelling vertical sliders is the same as we used above for switchers
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "", None, vertgroupslider), clearLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "A", None, vertgroupslider), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "B", None, vertgroupslider), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "C", None, vertgroupslider), switcherLabelStyle);
ESPUI.setElementStyle(ESPUI.addControl(Label, "", "D", None, vertgroupslider), switcherLabelStyle);
//Note that combining vertical and horizontal sliders is going to result in very messy layout!
/*
* Tab: Example UI
* An example UI for the documentation
*-----------------------------------------------------------------------------------------------------------*/
auto exampletab = ESPUI.addControl(Tab, "Example", "Example");
ESPUI.addControl(Separator, "Control and Status", "", None, exampletab);
ESPUI.addControl(Switcher, "Power", "1", Alizarin, exampletab, generalCallback);
ESPUI.addControl(Label, "Status", "System status: OK", Wetasphalt, exampletab, generalCallback);
ESPUI.addControl(Separator, "Settings", "", None, exampletab);
ESPUI.addControl(PadWithCenter, "Attitude Control", "", Dark, exampletab, generalCallback);
auto examplegroup1 = ESPUI.addControl(Button, "Activate Features", "Feature A", Carrot, exampletab, generalCallback);
ESPUI.addControl(Button, "Activate Features", "Feature B", Carrot, examplegroup1, generalCallback);
ESPUI.addControl(Button, "Activate Features", "Feature C", Carrot, examplegroup1, generalCallback);
ESPUI.addControl(Slider, "Value control", "45", Peterriver, exampletab, generalCallback);
/*
* Tab: WiFi Credentials
* You use this tab to enter the SSID and password of a wifi network to autoconnect to.
*-----------------------------------------------------------------------------------------------------------*/
auto wifitab = ESPUI.addControl(Tab, "", "WiFi Credentials");
wifi_ssid_text = ESPUI.addControl(Text, "SSID", "", Alizarin, wifitab, textCallback);
//Note that adding a "Max" control to a text control sets the max length
ESPUI.addControl(Max, "", "32", None, wifi_ssid_text);
wifi_pass_text = ESPUI.addControl(Text, "Password", "", Alizarin, wifitab, textCallback);
ESPUI.addControl(Max, "", "64", None, wifi_pass_text);
ESPUI.addControl(Button, "Save", "Save", Peterriver, wifitab, enterWifiDetailsCallback);
//Finally, start up the UI.
//This should only be called once we are connected to WiFi.
ESPUI.begin(HOSTNAME);
}
//This callback generates and applies inline styles to a bunch of controls to change their colour.
//The styles created are of the form:
// "border-bottom: #999 3px solid; background-color: #aabbcc;"
// "background-color: #aabbcc;"
void styleCallback(Control *sender, int type) {
//Declare space for style strings. These have to be static so that they are always available
//to the websocket layer. If we'd not made them static they'd be allocated on the heap and
//will be unavailable when we leave this function.
static char stylecol1[60], stylecol2[30];
if(type == B_UP) {
//Generate two random HTML hex colour codes, and print them into CSS style rules
sprintf(stylecol1, "border-bottom: #999 3px solid; background-color: #%06X;", (unsigned int) random(0x0, 0xFFFFFF));
sprintf(stylecol2, "background-color: #%06X;", (unsigned int) random(0x0, 0xFFFFFF));
//Apply those styles to various elements to show how controls react to styling
ESPUI.setPanelStyle(styleButton, stylecol1);
ESPUI.setElementStyle(styleButton, stylecol2);
ESPUI.setPanelStyle(styleLabel, stylecol1);
ESPUI.setElementStyle(styleLabel, stylecol2);
ESPUI.setPanelStyle(styleSwitcher, stylecol1);
ESPUI.setElementStyle(styleSwitcher, stylecol2);
ESPUI.setPanelStyle(styleSlider, stylecol1);
ESPUI.setElementStyle(styleSlider, stylecol2);
}
}
//This callback updates the "values" of a bunch of controls
void scrambleCallback(Control *sender, int type) {
static char rndString1[10];
static char rndString2[20];
static bool scText = false;
if(type == B_UP) { //Button callbacks generate events for both UP and DOWN.
//Generate some random text
randomString(rndString1, 10);
randomString(rndString2, 20);
//Set the various controls to random value to show how controls can be updated at runtime
ESPUI.updateLabel(mainLabel, String(rndString1));
ESPUI.updateSwitcher(mainSwitcher, ESPUI.getControl(mainSwitcher)->value.toInt() ? false : true);
ESPUI.updateSlider(mainSlider, random(10, 400));
ESPUI.updateText(mainText, String(rndString2));
ESPUI.updateNumber(mainNumber, random(100000));
ESPUI.updateButton(mainScrambleButton, scText ? "Scrambled!" : "Scrambled.");
scText = !scText;
}
}
void updateCallback(Control *sender, int type) {
updates = (sender->value.toInt() > 0);
}
void getTimeCallback(Control *sender, int type) {
if(type == B_UP) {
ESPUI.updateTime(mainTime);
}
}
void graphAddCallback(Control *sender, int type) {
if(type == B_UP) {
ESPUI.addGraphPoint(graph, random(1, 50));
}
}
void graphClearCallback(Control *sender, int type) {
if(type == B_UP) {
ESPUI.clearGraph(graph);
}
}
//Most elements in this test UI are assigned this generic callback which prints some
//basic information. Event types are defined in ESPUI.h
void generalCallback(Control *sender, int type) {
Serial.print("CB: id(");
Serial.print(sender->id);
Serial.print(") Type(");
Serial.print(type);
Serial.print(") '");
Serial.print(sender->label);
Serial.print("' = ");
Serial.println(sender->value);
}
void setup() {
randomSeed(0);
Serial.begin(115200);
while(!Serial);
if(SLOW_BOOT) delay(5000); //Delay booting to give time to connect a serial monitor
connectWifi();
#if defined(ESP32)
WiFi.setSleep(false); //For the ESP32: turn off sleeping to increase UI responsivness (at the cost of power use)
#endif
setUpUI();
}
void loop() {
static long unsigned lastTime = 0;
//Send periodic updates if switcher is turned on
if(updates && millis() > lastTime + 500) {
static uint16_t sliderVal = 10;
//Flick this switcher on and off
ESPUI.updateSwitcher(mainSwitcher, ESPUI.getControl(mainSwitcher)->value.toInt() ? false : true);
sliderVal += 10;
if(sliderVal > 400) sliderVal = 10;
//Sliders, numbers, and labels can all be updated at will
ESPUI.updateSlider(mainSlider, sliderVal);
ESPUI.updateNumber(mainNumber, random(100000));
ESPUI.updateLabel(mainLabel, String(sliderVal));
lastTime = millis();
}
//Simple debug UART interface
if(Serial.available()) {
switch(Serial.read()) {
case 'w': //Print IP details
Serial.println(WiFi.localIP());
break;
case 'W': //Reconnect wifi
connectWifi();
break;
case 'C': //Force a crash (for testing exception decoder)
#if !defined(ESP32)
((void (*)())0xf00fdead)();
#endif
default:
Serial.print('#');
break;
}
}
#if !defined(ESP32)
//We don't need to call this explicitly on ESP32 but we do on 8266
MDNS.update();
#endif
}
//Utilities
//
//If you are here just to see examples of how to use ESPUI, you can ignore the following functions
//------------------------------------------------------------------------------------------------
void readStringFromEEPROM(String& buf, int baseaddress, int size) {
buf.reserve(size);
for (int i = baseaddress; i < baseaddress+size; i++) {
char c = EEPROM.read(i);
buf += c;
if(!c) break;
}
}
void connectWifi() {
int connect_timeout;
#if defined(ESP32)
WiFi.setHostname(HOSTNAME);
#else
WiFi.hostname(HOSTNAME);
#endif
Serial.println("Begin wifi...");
//Load credentials from EEPROM
if(!(FORCE_USE_HOTSPOT)) {
yield();
EEPROM.begin(100);
String stored_ssid, stored_pass;
readStringFromEEPROM(stored_ssid, 0, 32);
readStringFromEEPROM(stored_pass, 32, 96);
EEPROM.end();
//Try to connect with stored credentials, fire up an access point if they don't work.
#if defined(ESP32)
WiFi.begin(stored_ssid.c_str(), stored_pass.c_str());
#else
WiFi.begin(stored_ssid, stored_pass);
#endif
connect_timeout = 28; //7 seconds
while (WiFi.status() != WL_CONNECTED && connect_timeout > 0) {
delay(250);
Serial.print(".");
connect_timeout--;
}
}
if (WiFi.status() == WL_CONNECTED) {
Serial.println(WiFi.localIP());
Serial.println("Wifi started");
if (!MDNS.begin(HOSTNAME)) {
Serial.println("Error setting up MDNS responder!");
}
} else {
Serial.println("\nCreating access point...");
WiFi.mode(WIFI_AP);
WiFi.softAPConfig(IPAddress(192, 168, 1, 1), IPAddress(192, 168, 1, 1), IPAddress(255, 255, 255, 0));
WiFi.softAP(HOSTNAME);
connect_timeout = 20;
do {
delay(250);
Serial.print(",");
connect_timeout--;
} while(connect_timeout);
}
}
void enterWifiDetailsCallback(Control *sender, int type) {
if(type == B_UP) {
Serial.println("Saving credentials to EPROM...");
Serial.println(ESPUI.getControl(wifi_ssid_text)->value);
Serial.println(ESPUI.getControl(wifi_pass_text)->value);
unsigned int i;
EEPROM.begin(100);
for(i = 0; i < ESPUI.getControl(wifi_ssid_text)->value.length(); i++) {
EEPROM.write(i, ESPUI.getControl(wifi_ssid_text)->value.charAt(i));
if(i==30) break; //Even though we provided a max length, user input should never be trusted
}
EEPROM.write(i, '\0');
for(i = 0; i < ESPUI.getControl(wifi_pass_text)->value.length(); i++) {
EEPROM.write(i + 32, ESPUI.getControl(wifi_pass_text)->value.charAt(i));
if(i==94) break; //Even though we provided a max length, user input should never be trusted
}
EEPROM.write(i + 32, '\0');
EEPROM.end();
}
}
void textCallback(Control *sender, int type) {
//This callback is needed to handle the changed values, even though it doesn't do anything itself.
}
void randomString(char *buf, int len) {
for(auto i = 0; i < len-1; i++)
buf[i] = random(0, 26) + 'A';
buf[len-1] = '\0';
}