Handling TCP Data stream

Projects Programming
1

I'm using ESPAsyncTCP with an ESP8266. I want to modify the program to send a larger amount of data. currently it is setup to send a single string but i want to send an array or struct. I need a way to orginize the data. I have a list of variables i would like to send to another esp module but how would i do this?

this is the example code im using i added a structer called sampleStruct this is the data i would like to send over tcp.

#include <ESP8266WiFi.h>
#include <ESPAsyncTCP.h>

extern "C" {
#include <osapi.h>
#include <os_type.h>
}

#include "config.h"

struct sampleStruct {
  int var1;
  float var2;
byte Array[20];
  unsigned long var3;
  unsigned long var4;
  unsigned long var5;
  unsigned long var6;
  unsigned long var7;
  unsigned long var8;
  bool var9;
};

static os_timer_t intervalTimer;

static void replyToServer(void* arg) {
	AsyncClient* client = reinterpret_cast<AsyncClient*>(arg);

	// send reply
	if (client->space() > 32 && client->canSend()) {
		char message[32];
		sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
		client->add(message, strlen(message));
		client->send();
	}
}


/* event callbacks */
static void handleData(void* arg, AsyncClient* client, void *data, size_t len) {
	Serial.printf("\n data received from %s \n", client->remoteIP().toString().c_str());
	Serial.write((uint8_t*)data, len);

	os_timer_arm(&intervalTimer, 2000, true); // schedule for reply to server at next 2s
}

void onConnect(void* arg, AsyncClient* client) {
	Serial.printf("\n client has been connected to %s on port %d \n", SERVER_HOST_NAME, TCP_PORT);
	replyToServer(client);
}


void setup() {
	Serial.begin(115200);
	delay(20);

	// connects to access point
	WiFi.mode(WIFI_STA);
	WiFi.begin(SSID, PASSWORD);
	while (WiFi.status() != WL_CONNECTED) {
		Serial.print('.');
		delay(500);
	}

	AsyncClient* client = new AsyncClient;
	client->onData(&handleData, client);
	client->onConnect(&onConnect, client);
	client->connect(SERVER_HOST_NAME, TCP_PORT);

	os_timer_disarm(&intervalTimer);
	os_timer_setfn(&intervalTimer, &replyToServer, client);
}

void loop() {

}

I've had a hard time trying to find documentation on this AsyncTCP server. Would i send each variable 1 at a time? How can i achieve what im trying to do?

2

I really need some advice please.

3

Looks to me like you would change:

		char message[32];
		sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
		client->add(message, strlen(message));

to:

client->add(ArrayOfStructs, sizeof ArrayOfStructs);
4

johnwasser:
Looks to me like you would change:

		char message[32];

	sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
	client->add(message, strlen(message));



to:

client->add(ArrayOfStructs, sizeof ArrayOfStructs);

I tried "client->add(sampleStruct, sizeof sampleStruct);"

when i try to compile if gives me this error,

expected primary-expression before ',' token

so i tried "client->add(&sampleStruct, sizeof sampleStruct);"

and got the same result. I have not found any documentation how to use the library either

5

I also tried this,

struct sampleStruct {
  int var1;
  byte Array[20];
  float var2;
  unsigned long var3;
  unsigned long var4;
  unsigned long var5;
  unsigned long var6;
  unsigned long var7;
  unsigned long var8;
  bool var9;
};
sampleStruct st;
static os_timer_t intervalTimer;

static void replyToServer(void* arg) {
	AsyncClient* client = reinterpret_cast<AsyncClient*>(arg);

	// send reply
	if (client->space() > 32 && client->canSend()) {
//		char message[32];
//		sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
//		client->add(message, strlen(message));
//		client->send();
client->add(&st, sizeof(sampleStruct));
	}
}

i get a different error,

exit status 1
no matching function for call to 'AsyncClient::add(sampleStruct*, unsigned int)'

6

Yes. Apparently you have to cast the pointer:

static void replyToServer(void* arg)
{
  AsyncClient* client = reinterpret_cast<AsyncClient*>(arg);


  // send reply
  if (client->space() > 32 && client->canSend())
  {
    //    char message[32];
    //    sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
    //    client->add(message, strlen(message));
    client->add((char *)&st, sizeof(sampleStruct));
    client->send();
  }
}

The error message tells you the line and character at which the error was detected.

Your previous error ("expected primary-expression before ',' token") was caused by trying to use a data type as a variable. The type 'enum sampleStruct' doesn't have an address. The variable 'st' does.

7

johnwasser:
Yes. Apparently you have to cast the pointer:

static void replyToServer(void* arg)

{
  AsyncClient* client = reinterpret_cast<AsyncClient*>(arg);

// send reply
  if (client->space() > 32 && client->canSend())
  {
    //    char message[32];
    //    sprintf(message, "this is from %s", WiFi.localIP().toString().c_str());
    //    client->add(message, strlen(message));
    client->add((char *)&st, sizeof(sampleStruct));
    client->send();
  }
}





The error message tells you the line and character at which the error was detected.

Your previous error ("expected primary-expression before ',' token") was caused by trying to use a data type as a variable. The type 'enum sampleStruct' doesn't have an address. The variable 'st' does.

Thankyou that did the trick. I really really really appreciate the help