A battery-operated receiver with RS-232 serial output plus a 3-color LED and a speaker

This is the first RF receiver I made. The motive was prompted by a discount buy of a commercial smoke detectot which ran off 12V in late 2012. My RV came with a 12V smoke detector which had failed, so I wanted to replace it with this one. Wanting to be notified if it went off while parked outside my house, I added a transmitter to it and made this receiver in early 2013. It was with this combination that I worked out the hardware and software to get reliable communications without false alarms. I especially did not want to rush out to check on the RV at night, because I sleep naked!

The RV was sold in 2014 with the transmitter removed from the smoke detector. Its transmitting module has been re-used in another project.

This receiver is now used to monitor the gate transmissions. No hardware changes were made.
This is the only battery-powered receiver, and is therefore portable. Unfortunally it has to be recharged every 2 weeks.

This is the inside. The circuit board at right slides into a slot and plugs into the antenna. The receiver module is visible at top.
The assembly with the connectors also slides out. It holds the battery.

This is the circuit Board

Here are the circuit diagrams:

Here is the code for announcing the gate operation transmissions with both tunes and colors.
It is customable by altering constants and DATA statements.
More inputs, sounds and tunes can easily be added. The "h" key is spare.