- This module allows you to do "debugging over the air". So if you already use ArduinoOTA, this is a helpful extension for wireless development. Use ```TelnetSpy``` instead of ```Serial``` to send data to the serial port and a copy to a Telnet connection.
- There is a circular buffer which allows to store the data while the Telnet connection is not established. So it's possible to collect data even when the WiFi and Telnet connections are not yet established.
- It's also possible to create a Telnet session only if it is neccessary: then you will get the already collected data as far as it is still stored in the circular buffer. Data sent from Telnet terminal to ESP8266 / ESP32 will be handled as data received by serial port.
- It is also possible to use more than one instance of TelnetSpy. For example - To send control information on the first instance and data dumps on the second instance.
### 7. bool setBufferSize(uint16_t newSize) <a name = "setBufferSize"></a>
Change the size of the ring buffer. Set it to ```0``` to disable buffering. Changing size tries to preserve the already collected data. If the new buffer size is too small, only the latest data will be preserved. Returns ```false``` if the requested buffer size cannot be set.
### 9. void setStoreOffline(bool store) <a name = "setStoreOffline"></a>
Enable / disable storing new data in the ring buffer if no Telnet connection is established. This function allows you to store important data only. You can do this by disabling ```storeOffline``` for sending unimportant data.
### 11. void setPingTime(uint16_t pngTime) <a name = "setPingTime"></a>
If no data is sent via TelnetSpy, the detection of a disconnected client has a long timeout. Use ```setPingTime``` to define the time (in ms) without traffic after which a ping aka a ```chr(0)``` is sent to the Telnet client to detect a disconnect earlier. Use ```0``` as parameter to disable pings.
### 14. void setCallbackOnConnect(void (*callback)()) <a name = "setCallbackOnConnect"></a>
This function installs a callback function which will be called on every Telnet connect of this object (except rejected connect tries). Use ```NULL``` to remove the callback.
### 15. void setCallbackOnDisconnect(void (*callback)()) <a name = "setCallbackOnDisconnect"></a>
This function installs a callback function which will be called on every Telnet disconnect of this object (except rejected connect tries). Use ```NULL``` to remove the callback.
Replace ```Serial``` with ```SERIAL``` in your sketch. Now you can switch between serial only and serial with Telnet by only changing the comments of the defines.
- Everything you do with ```Serial```, you can do with ```TelnetSpy``` too. But remember: Transfering data also via Telnet will need more performance than the serial port only. So time critical things may be influenced.
- Usage of ```void setDebugOutput(bool)``` to enable / disable of capturing of os_print calls when you have more than one TelnetSpy instance: That TelnetSpy object will handle this functionality where you used ```setDebugOutput``` at last.
On default, TelnetSpy has the capturing of OS_print calls enabled. So if you have more instances the last created instance will handle the capturing.
