WiFi in Client mode.

[spankywetfish]

Just a question really, have you tried this "successfully" in WiFi client mode or just in AP mode ?
The reason I'm asking is I was thinking about adding other notification methods (e.g. slack webhook or similar), for no reason other than it's something to do.

I made a couple of minor changes to make the ESP32 available on a local network and it connects just fine.
The IP is output to the LCD and Serial prior to the welcome messages and I can access the Web UI no problem.
It then sits waiting for a card to be swiped as usual.
However for some reason, swiping a card doesn't register, there is the usual beep and LED flash but no serial or web notifications.
I'm a tad perplexed how such a simple change could interfere with the card swipe functionality, unless client mode WiFi some how interferes with the data pins connected with the reader ¯\_(ツ)_/¯

If you wanted to try this out, this is all I did.

Added consts for ssid and password then modified the setupWifi function as follows...

void setupWifi() {
  WiFi.begin(ssid, password);
  WiFi.setSleep(false);
  lcd.clear();
  lcd.setCursor(0, 0);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    lcd.print("*");
  }
  
  const String local_ip = WiFi.localIP().toString();
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print(local_ip);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(centerText("WiFi connected", 20));
  lcd.setCursor(0, 2);
  lcd.print(centerText(local_ip, 20));
  delay(5000);
}

[spankywetfish]

I've made a little progress in troubleshooting this.
It seems that any calls to a WiFi function borks the ability to read cards.
As an example reverting back to the original code, I added a line to output the AP IP address after initialisation.

e.g.

void setupWifi() {
 WiFi.softAP(ap_ssid, ap_passphrase, ap_channel, ssid_hidden);
 Serial.println(WiFi.softAPIP().toString());
}

and this breaks the ability to read cards.

So any of the WiFi functions in the previous post could cause this to bork, be it, setSleep, status or localIP, without which making a client connection becomes a tad onerous.

[spankywetfish]

I've done a bit more work on this and it appears to be a memory/storage issue.
After adding additional fields to the web page and subsequent code for the ssid and passphrase of an AP to connect to in STA mode, I hit the same issue of not being able to read cards, this time in the original AP mode.

I commented out all the code I had added and then line by line re-added them, eventually hitting the last two lines of added code that read the stored STA SSID and Passphrase from preferences.
I then set about trying to compress the code as much as possible, this meant removing excess whitespace from the html/javascript section amongst other things.
My last compile resulted in...

Sketch uses 1053080 bytes (80%) of program storage space. Maximum is 1310720 bytes.
Global variables use 60104 bytes (18%) of dynamic memory, leaving 267576 bytes for local variables. Maximum is 327680 bytes.

which is roughly 6k less than the original code...

Sketch uses 1059296 bytes (80%) of program storage space. Maximum is 1310720 bytes.
Global variables use 60072 bytes (18%) of dynamic memory, leaving 267608 bytes for local variables. Maximum is 327680 bytes.

With this more compacted version I have successfully achieved a connection in STA mode while maintaining the ability to read cards/displaying them on the LCD and web page.
It's still not ideal as you have to have visibilty of your DHCP server in order to know what IP the web page will be visible on, but it's functional.

Next on the agenda is callouts to slack or maybe HA to switch on/off a light when a card is successfully swiped, but i fear that will increase the resource usage yet more and subsequently break card reading again.