Documentation

// ESP32-WROVER - PSRAM check + WiFi scan
// Arduino IDE: Tools -> Board -> "ESP32 Wrover Module", PSRAM: "Enabled"

#include <WiFi.h>

void setup() {
  Serial.begin(115200);
  delay(500);

  Serial.printf("Chip: %s, %d cores @ %d MHz\n",
                ESP.getChipModel(), ESP.getChipCores(), ESP.getCpuFreqMHz());
  Serial.printf("Flash: %u bytes\n", ESP.getFlashChipSize());
  Serial.printf("PSRAM: %u bytes (%s)\n", ESP.getPsramSize(),
                psramFound() ? "FOUND" : "NOT FOUND");

  // Allocate 1MB in PSRAM to prove it's usable
  uint8_t *big = (uint8_t *)ps_malloc(1024 * 1024);
  Serial.printf("1MB PSRAM alloc: %s\n", big ? "OK" : "FAILED");
  if (big) free(big);

  WiFi.mode(WIFI_STA);
  Serial.println("\nScanning WiFi...");
  int n = WiFi.scanNetworks();
  for (int i = 0; i < n; i++) {
    Serial.printf("%2d: %-24s %d dBm\n",
                  i + 1, WiFi.SSID(i).c_str(), WiFi.RSSI(i));
  }
}

void loop() {}

// ESP32-WROVER - download into a PSRAM buffer
// Fill in your WiFi credentials before uploading.

#include <WiFi.h>
#include <HTTPClient.h>

const char *SSID = "YOUR_WIFI";
const char *PASS = "YOUR_PASSWORD";

void setup() {
  Serial.begin(115200);
  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED) { delay(300); Serial.print("."); }
  Serial.printf("\nConnected: %s\n", WiFi.localIP().toString().c_str());

  // 2MB buffer - impossible on a WROOM, trivial on a WROVER
  size_t cap = 2 * 1024 * 1024;
  uint8_t *buf = (uint8_t *)ps_malloc(cap);
  Serial.printf("PSRAM buffer: %s\n", buf ? "allocated" : "failed");

  HTTPClient http;
  http.begin("http://example.com/");
  int code = http.GET();
  if (code == 200) {
    String body = http.getString();
    size_t n = min((size_t)body.length(), cap);
    memcpy(buf, body.c_str(), n);
    Serial.printf("Fetched %u bytes into PSRAM. First line:\n", n);
    Serial.println(body.substring(0, body.indexOf('\n')));
  } else {
    Serial.printf("HTTP error: %d\n", code);
  }
  http.end();
  free(buf);
}

void loop() {}

# Flash MicroPython (SPIRAM build!) onto the WROVER over UART:
#   pip install esptool
#   esptool --port /dev/ttyUSB0 erase_flash
#   esptool --port /dev/ttyUSB0 --baud 460800 write_flash 0x1000 \
#       ESP32_GENERIC-SPIRAM-latest.bin
# (download the GENERIC-SPIRAM firmware from micropython.org)

# Then at the REPL:
import gc, esp, machine

print("CPU MHz:", machine.freq() // 1_000_000)
print("Flash size:", esp.flash_size())

gc.collect()
print("Free RAM:", gc.mem_free())   # ~4MB free = PSRAM active

# Allocate a 2MB bytearray - only possible with PSRAM
big = bytearray(2 * 1024 * 1024)
print("2MB bytearray OK, length:", len(big))

# ESP32-WROVER - MicroPython WiFi scan
import network
import time

sta = network.WLAN(network.STA_IF)
sta.active(True)

print("Scanning...")
for ssid, bssid, ch, rssi, sec, hidden in sta.scan():
    print("{:24s} ch{:2d} {:4d} dBm".format(ssid.decode(), ch, rssi))

# Simple connect helper
def connect(ssid, password, timeout=15):
    sta.connect(ssid, password)
    t0 = time.time()
    while not sta.isconnected():
        if time.time() - t0 > timeout:
            raise RuntimeError("WiFi connect timeout")
        time.sleep(0.5)
    print("Connected:", sta.ifconfig()[0])

# connect("YOUR_WIFI", "YOUR_PASSWORD")