ESP8266 Community Forum

Posted: **Mon Jan 29, 2018 2:29 am**

Hi, I have a couple of issues. It should be simple for the experienced..

1) I don't know how to convert a stream of serial bytes to a string variable.

I have the following code:

Code: Select all

    
int size;
    while ((size = client.available()) > 0) {
      uint8_t* msg = (uint8_t*)malloc(size);
      size = client.read(msg, size);
      Serial.write(msg, size);

      //String chineseSurname = msg.toString();  // error: request for member 'toString' in 'msg', which is of non-class type 'uint8_t* {aka unsigned char*}'
      //String chineseSurname = String(msg);
      //String chineseSurname = String(msg,size);
      String chineseSurname.concat(msg, size);
     
free(msg);
    }

I'm trying to get the value in Serial.write (msg, size) into a string variable, but I don't know how to do it. I've tried the options above but none of them work.

2) Serial Monitor

My serial monitor is flaky. Sometimes it works, sometimes it doesn't. I actually don't know how or when to use it.

a) does it only work when uploading via USB?
b) could it also read serial output of the ESP without re-uploading the code? In other words, if I find an ESP-01 on the ground, can I plug it in my USB adapter and read its serial output?
c) How does it work, do I have to open the Serial Monitor before uploading for it to read the serial output, or can I open it any time?
d) Do I have to open the Serial Monitor before plugging in the ESP into a USB CH340 adapter or do I open it after the device is plugged in to the USB adapter?
e) Some of my codes work and some doesn't.

Code: Select all

void setup() {
  Serial.begin(115200);
  Serial.println("LED Example.");
  delay(1000);                      // Wait for a second
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
                                    // but actually the LED is on; this is because
                                    // it is acive low on the ESP-01)
  Serial.println("LED On!");
  delay(1000);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  Serial.println("LED Off!");
  delay(2000);                      // Wait for two seconds (to demonstrate the active low LED)
}

WIth this code, only "LED Example." is written on the serial monitor. But the "LED On" and "LED Off" messages are never seen on the serial monitor. The LED on the ESP does blink blue on and off every second though.

Code: Select all

#include <ESP8266WiFi.h>

const char* ssid = "Hotspot";
const char* password = "00000000";

// Create an instance of the server
// specify the port to listen on as an argument
WiFiServer server(80);

void setup() {
  Serial.begin(115200);
  delay(10);

  // prepare GPIO1
  pinMode(1, OUTPUT);
  digitalWrite(1, 1); delay(1000); 
  digitalWrite(1, 0); delay(200); digitalWrite(1, 1); delay(200); digitalWrite(1, 0); delay(200); 
  digitalWrite(1, 1); delay(2000);
  digitalWrite(1, 0); delay(200); digitalWrite(1, 1); delay(200); digitalWrite(1, 0); delay(200); 
  digitalWrite(1, 1);
  
  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  
  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.println(WiFi.localIP());
}

void loop() {
  WiFiClient client;
  // Check if a client has connected
  client = server.available();
  if (!client) {
    Serial.println("waiting for connection.");
    return;
  }
  
  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    Serial.println("waiting for data.");
    delay(1);
  }
}

This one returns only garbage in the serial monitor:
hksum 0x2d
csum 0x2d
v4ceabea9
~ld

I don't see any of my Serial.prints on the serial monitor. But the two double blinks does work every time it boots up. Just that there are no serial messages coming in.

3) COM Error

I get a java error about the com port every time I try to upload. I have to press upload twice to get the code to upload. This happens even if I click Verify/Compile first or just straight Upload.

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Uploading to I/O Board...

java.io.IOException: jssc.SerialPortException: Port name - COM3; Method name - setEventsMask(); Exception type - Can't set mask.
   at processing.app.Serial.dispose(Serial.java:166)
   at processing.app.SerialMonitor.close(SerialMonitor.java:116)
   at processing.app.AbstractMonitor.suspend(AbstractMonitor.java:90)
   at processing.app.Editor$DefaultExportHandler.run(Editor.java:2160)
   at java.lang.Thread.run(Thread.java:748)
Caused by: jssc.SerialPortException: Port name - COM3; Method name - setEventsMask(); Exception type - Can't set mask.
   at jssc.SerialPort.setEventsMask(SerialPort.java:279)
   at jssc.SerialPort.removeEventListener(SerialPort.java:1064)
   at jssc.SerialPort.closePort(SerialPort.java:1090)
   at processing.app.Serial.dispose(Serial.java:163)
   ... 4 more

Thanks for reading this far.

I'm sure these are actually stupid questions but I really don't know how to figure it out and I don't even know what the right Google search terms to type, I've tried all that I could think off.

Cheers
aledrus

Posted: **Fri Feb 02, 2018 3:19 pm**

Hello

I solved (1) & (2).

(1) First cast the byte into a char array, then convert the char array to String. Now with the String, I could use the indexOf and substring functions.

(2) Apparently the serial monitor wouldn't work if I also want to monitor the blue LED. It's either blink the blue LED to report the status of the execution, or monitor with the Serial Monitor without the blue LED.

(3) I don't know what this is about yet, so far I can just double-click "Upload" and it will upload.

Posted: **Fri Feb 02, 2018 8:22 pm**

I used to have trouble with uploading code. Lots of strange error codes leading to Google red herring searches but the following works for me:

1. Run in Administrator mode
2. Turn firewall off
3. Disable real time virus scanning

ESP8266 Community Forum

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