Read serial port for specific text then trigger attached Wifi sensor

I'm looking for some help surrounding a very small project I have been looking to do. Basically I have a requirement to read the output from a serial port (currently an RJ45 connector) and check the output. Based on the output, I then need to trigger a Wifi sensor which will be handled outside of this project on a web interface/android app of my creation at a later date.

The serial output will be a series of fullstops repeating (......) and upon this series of fullstops no longer being the output from the serial port, I need the Wifi sensor to be triggered. The Wifi sensor is an ESP8266 and I'm looking to make this as small as possible (ATTiny45 or smaller?)

Can anyone help me construct a prototype through an arduino or directly onto the tiny45 that allows this to happen. I can either take power from an external battery pack or possibly from the serial port itself if such power even exists...

If anyone needs more information, please feel free to ask.

Thanks

kaotix:
I’m looking for some help surrounding a very small project I have been looking to do.
Basically I have a requirement to read the output from a serial port (currently an RJ45 connector) and check the output. Based on the output, I then need to trigger a Wifi sensor which will be handled outside of this project on a web interface/android app of my creation at a later date.

The serial output will be a series of fullstops repeating (…) and upon this series of fullstops no longer being the output from the serial port, I need the Wifi sensor to be triggered.
The Wifi sensor is an ESP8266 and I’m looking to make this as small as possible (ATTiny45 or smaller?)

Can anyone help me construct a prototype through an arduino or directly onto the tiny45 that allows this to happen. I can either take power from an external battery pack or possibly from the serial port itself if such power even exists…

If anyone needs more information, please feel free to ask.

Thanks

A quick google stated that a full-stop character is the PERIOD character, ASCII 46 DEC.

What you do not say is the BAUD if every character at that BAUD is a period. Or, are periods more sparse, like every 0.10 seconds? It matters.

You need to build a state-machine to monitor the serial port in a loop. As long as the character is a period and that character falls into the reset time-frame, then you do nothing. When a period has not been received within the critical time period, then you activate the WiFi. The state machine then turns off the WiFi, sends a message, etc. until it is time to clear the timer and monitor the serial port once again.

There is a post titled “Topic: Doing multiple things at the same time.” which you can Google and read. IT will be helpful in understanding how to build the skeleton of your state machine sketch.

Ray