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WiFi Repeater (Part One)

Part of the program to monitor and automate some things around the property naturally enough includes extending the WiFi network to cover a wider area. There are a number of ways of doing this, including:

1. Buying a decent router and channelling heaps of power into it for coverage

2. Buying WiFi extenders/repeaters and wiring them in all over the place

3. Coming up with some half-baked plan to use $1 ESP-01 devices running on solar power (in Tasmania!)

Of these options, which do you think this post is essentially about? 

There are a number of options for setting up such a (cheap) extended network, and it may take a few blogs/videos to explore and evaluate some options. On my list is the following:

1. Can I program the ESP-01 to accept home WiFi?
2. Which extender/repeater software for the ESP-01 suits my needs?
3. Test the network under various conditions to help me make the decision
4. Work on Solar/Battery combinations that work for spreading the network around a rural property 

5. Design and 3D print a weather-resistant project box

On the programming front, the little adapters are great, however there seem to be two main types. One is just a cradle for the ESP-01 and needs some soldering and a button added to be used as a programmer (see video), whilst the other comes with an integrated button and can be switched between "PROG" and "UART" mode.  

Then it's a matter of choosing your programming method - you can use Esptool, Espressif's tools or (as in my case) the Arduino IDE.

Once the connections and programming was sorted (i.e. can I blink a LED!) I then used the following OTA code modified from the ESP8266 WiFi extender code:

// NAPT example released to public domain

#if LWIP_FEATURES && !LWIP_IPV6

#define HAVE_NETDUMP 0

#ifndef STASSID
#define STASSID "*****************"
#define STAPSK  "*****************"
#endif

#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>
#include <lwip/napt.h>
#include <lwip/dns.h>
#include <LwipDhcpServer.h>

const char* ssid = STASSID;
const char* password = STAPSK;
const char* host = "HostName";

#define NAPT 1000
#define NAPT_PORT 10


void setup() {
  Serial.begin(115200);
  Serial.printf("\n\nNAPT Range extender\n");
  Serial.printf("Heap on start: %d\n", ESP.getFreeHeap());

#if HAVE_NETDUMP

#include <NetDump.h>

  void dump(int netif_idx, const char* data, size_t len, int out, int success) {
    (void)success;
    Serial.print(out ? F("out ") : F(" in "));
    Serial.printf("%d ", netif_idx);

    // optional filter example: if (netDump_is_ARP(data))
    {
      netDump(Serial, data, len);
      //netDumpHex(Serial, data, len);
    }
  }
#endif

#if HAVE_NETDUMP
  phy_capture = dump;
#endif

  // first, connect to STA so we can get a proper local DNS server
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print('.');
    delay(500);
  }
  Serial.printf("\nSTA: %s (dns: %s / %s)\n",
                WiFi.localIP().toString().c_str(),
                WiFi.dnsIP(0).toString().c_str(),
                WiFi.dnsIP(1).toString().c_str());

  // give DNS servers to AP side
  dhcpSoftAP.dhcps_set_dns(0, WiFi.dnsIP(0));
  dhcpSoftAP.dhcps_set_dns(1, WiFi.dnsIP(1));

  WiFi.softAPConfig(  // enable AP, with android-compatible google domain
    IPAddress(172, 217, 28, 254),
    IPAddress(172, 217, 28, 254),
    IPAddress(255, 255, 255, 0));
  WiFi.softAP("WiFi-Mesh", STAPSK);
  Serial.printf("AP: %s\n", WiFi.softAPIP().toString().c_str());

  Serial.printf("Heap before: %d\n", ESP.getFreeHeap());
  err_t ret = ip_napt_init(NAPT, NAPT_PORT);
  Serial.printf("ip_napt_init(%d,%d): ret=%d (OK=%d)\n", NAPT, NAPT_PORT, (int)ret, (int)ERR_OK);
  if (ret == ERR_OK) {
    ret = ip_napt_enable_no(SOFTAP_IF, 1);
    Serial.printf("ip_napt_enable_no(SOFTAP_IF): ret=%d (OK=%d)\n", (int)ret, (int)ERR_OK);
    if (ret == ERR_OK) {
      Serial.printf("WiFi Network '%s' with same password is now NATed behind '%s'\n", "Charis-Mesh", STASSID);
    }
  }
  Serial.printf("Heap after napt init: %d\n", ESP.getFreeHeap());
  if (ret != ERR_OK) {
    Serial.printf("NAPT initialization failed\n");
  }
  ArduinoOTA.setHostname(host);
  ArduinoOTA.setPassword("MyPass");
  ArduinoOTA.onError([](ota_error_t error) {
    (void)error;
    ESP.restart();
  });
  /* setup the OTA server */
  ArduinoOTA.begin();
  Serial.println("Ready");

}

#else

void setup() {
  Serial.begin(115200);
  Serial.printf("\n\nNAPT not supported in this configuration\n");
}

#endif

void loop() {
  ArduinoOTA.handle();
}

The video below shows this system in a link of WiFi SSIDs stretching about 60m down the driveway as per this diagram:

I'm currently evaluating a slightly different way of putting the network "Mesh" together, but I'll save that for another video/blog.