Yet another AT Commands question - with a twist

Projects Programming
5

Here's an Arduino project over at Instructables.com
Oddly, it clearly directs you to upload a sketch and THEN......use the AT command ?
Throughout the uploaded sketch, it depends on AT commands send automatically.
If the sketch overwrites the ability for the ESP8266 to respond to AT commands, how can this ever work?

Is it that this sketch only uploads to the Arduino and NOT into the ESP8266?

How can this be?

Here's the sketch.....

#include <DHT.h>
#include <DHT_U.h>
#include <stdlib.h>

#define SSID "YourSSID"//your network name
#define PASS "YourPassword"//your network password
#define NIP "184.106.153.149" // thingspeak.com
#define DHTPIN 7 // what pin the DHT sensor is connected to
#define DHTTYPE DHT11 // Change to DHT22 if that's what you have
#define Baud_Rate 115200 //Another common value is 9600
#define GREEN_LED 3 //optional LED's for debugging
#define RED_LED 4 //optional LED's for debugging
#define DELAY_TIME 60000 //time in ms between posting data to ThingSpeak

//Can use a post also
String GET = "GET /update?key=1234567&field1=";
String FIELD2 = "&field2=";

//if you want to add more fields this is how
//String FIELD3 = "&field3=";

bool updated;

DHT dht(DHTPIN, DHTTYPE);

//this runs once
void setup()
{
Serial.begin(Baud_Rate);
Serial.println("AT");

delay(10000);

if(Serial.find("OK")){
//connect to your wifi netowork
bool connected = connectWiFi();
if(!connected){
//failure, need to check your values and try again
Error();
}
}else{
Error();
}

//initalize DHT sensor
dht.begin();
}

//this runs over and over
void loop(){
float h = dht.readHumidity();
// Read temperature as Fahrenheit (isFahrenheit = true)
float f = dht.readTemperature(true);

// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(f)) {
LightRed();
return;
}

//update ThingSpeak channel with new values
updated = updateTemp(String(f), String(h));

//if update succeeded light up green LED, else light up red LED
if(updated){
LightGreen();
}else{
LightRed();
}

//wait for delay time before attempting to post again
delay(DELAY_TIME);
}

bool updateTemp(String tenmpF, String humid){
//initialize your AT command string
String cmd = "AT+CIPSTART="TCP","";

//add IP address and port
cmd += NIP;
cmd += "",80";

//connect
Serial.println(cmd);
delay(2000);
if(Serial.find("Error")){
return false;
}

//build GET command, ThingSpeak takes Post or Get commands for updates, I use a Get
cmd = GET;
cmd += tenmpF;
cmd += FIELD2;
cmd += humid;

//continue to add data here if you have more fields such as a light sensor
//cmd += FIELD3;
//cmd += <field 3 value>

cmd += "\r\n";

//Use AT commands to send data
Serial.print("AT+CIPSEND=");
Serial.println(cmd.length());
if(Serial.find(">")){
//send through command to update values
Serial.print(cmd);
}else{
Serial.println("AT+CIPCLOSE");
}

if(Serial.find("OK")){
//success! Your most recent values should be online.
return true;
}else{
return false;
}
}

boolean connectWiFi(){
//set ESP8266 mode with AT commands
Serial.println("AT+CWMODE=1");
delay(2000);

//build connection command
String cmd="AT+CWJAP="";
cmd+=SSID;
cmd+="","";
cmd+=PASS;
cmd+=""";

//connect to WiFi network and wait 5 seconds
Serial.println(cmd);
delay(5000);

//if connected return true, else false
if(Serial.find("OK")){
return true;
}else{
return false;
}
}

void LightGreen(){
digitalWrite(RED_LED, LOW);
digitalWrite(GREEN_LED, HIGH);
}

void LightRed(){
digitalWrite(GREEN_LED, LOW);
digitalWrite(RED_LED, HIGH);
}

//if an error has occurred alternate green and red leds
void Error(){
while(true){
LightRed();
delay(2000);
LightGreen();
delay(2000);
}
}