Uno R4 · Wi-Fi access point and HTTP peer

// SPDX-License-Identifier: MIT
// First-party peer for the unchanged official AP_SimpleWebServer fixture.
#include <WiFiS3.h>
void setup() {
  Serial.begin(9600);
  if (WiFi.begin("testAP", "123456789") != WL_CONNECTED) {
    Serial.println("peer association failed");
    while (true) delay(1000);
  }
  delay(11000); // Official server waits ten seconds before listening.
}
void loop() {
  static bool high = true;
  WiFiClient client;
  if (!client.connect(IPAddress(192,48,56,2), 80)) {
    Serial.println("peer connection failed");
    delay(1000);
    return;
  }
  client.print(high ? "GET /H HTTP/1.0\r\n" : "GET /L HTTP/1.0\r\n");
  client.print("Host: r4-peer\r\n\r\n");
  unsigned long start = millis();
  while ((client.connected() || client.available()) && millis() - start < 3000) {
    while (client.available()) Serial.write(client.read());
  }
  client.stop();
  Serial.println(high ? "peer done H" : "peer done L");
  high = !high;
  delay(2000);
}