[Alex] had an old FM radio tuner card come his way. It used an ISA connector, a standard that went the way of the dodo in the mid-nineties. With the challenge of implementing an ISA-bus to configure the card he set out on his mission. What he came up with is a working radio using the ISA card and driven by a PIC 16F877. Join us after the break for schematic, code, and a few details.
The card is based on an LM7000 PLL synthesizer paired with a LC7534 tone/volume controller. With a bit of datasheet study [Alex] figured out where the data pins for the chips map to the ISA bus. Working with a prototyping board, the hardest part turned out to be finding the addresses for the chips. He ended up testing all 256 possibilities and watching for the data to be latched from the ISA bus. Alex says the hardware is capable of tuning from about 60MHz up to 125MHz.
We asked him if he’d share his code and schematic. He came through with both, and kudos to him for such a clean hand-drawn schematic. Nice work [Alex]!
Source Code (Tarball)