M5Stackの液晶右上に無線LANのアンテナを表示する簡単なサンプルスケッチ。

#include <WiFi.h>
#include <M5Stack.h>

const char* ssid     = "ssid";
const char* password = "pass";

unsigned long currentMillis;
unsigned long lastupdateMillis = 0;

#define RGB(r,g,b) (int16_t)(b + (g << 5) + (r << 11)) //色0～31 緑は0～63

void wifi_antenna(bool force=false) {
	if (currentMillis - lastupdateMillis > 500 || force) {
		if (WiFi.status() != WL_CONNECTED) {
			M5.Lcd.fillRect(280, 5, 40, 20, RGB(0, 0, 0));
			M5.Lcd.fillRect(280, 23, 40, 2, RED);
		} else {
			long rssi = WiFi.RSSI();
			int siglevel;
			if (rssi <= -96)
				siglevel = 1;
			else if (rssi <= -85)
				siglevel = 2;
			else if (rssi <= -75)
				siglevel = 3;
			else
				siglevel = 4;
			M5.Lcd.fillRect(280, 5, 40, 20, RGB(0, 0, 0));
			if (siglevel >= 1)
				M5.Lcd.fillRect(280, 20, 5, 5, RGB(20, 20, 25));
			if (siglevel >= 2)
				M5.Lcd.fillRect(290, 15, 5, 10, RGB(20, 20, 27));
			if (siglevel >= 3)
				M5.Lcd.fillRect(300, 10, 5, 15, RGB(20, 20, 29));
			if (siglevel >= 4)
				M5.Lcd.fillRect(310, 5, 5, 20, RGB(20, 20, 31));
		}
		lastupdateMillis = currentMillis;
	}
}

void setup()
{
	M5.begin();
	M5.Lcd.print("Connecting to ");
	M5.Lcd.println(ssid);

	WiFi.begin(ssid, password);

	while (WiFi.status() != WL_CONNECTED) {
		delay(500);
	}

	M5.Lcd.print("Connected. IP address: ");
	M5.Lcd.println(WiFi.localIP());
	wifi_antenna(true);
}

void loop() {
	currentMillis = millis();
	wifi_antenna();
	M5.update();
}