These pages are a useful collection of microcontroller RS-232 data acquisition circuits and code. Most of the code on these pages is written in C because it is the language that is definitely the fastest way to produce working applications.
The Micro Stop – RS232 microcontroller schematics
RS232 controlled and RS232 powered DVM-001 voltmeter kit with PC voltage display. This circuit uses a PIC12F675 8-pin microcontroller with built-in analog to digital converter. The circuit also has an op amp and resistor divider network to achieve the 54vdc max input voltage.