Posted on Monday, December 27, 2010 • Category: Miscellaneous
I decided to build a device to permanently display accurate time received from a cheap GPS module installed in my workshop.
Having obtained a PIC18F1320 microcontroller for experimentation, I wanted to learn about the new features of the PIC18F range using only minimal hardware to control the display.
I am currently using it with the on-chip 8Mhz oscillator only and driving a six digit led display, multiplexed with further saving of chip pins by a technique pioneered by Charlie Allen of Maxim-Dallas for their MAX6951 LED display drivers called “Charlieplexing” (see their application note AN1880).
I would have liked to have used a MAX6951 chip for better display brightness, but they appear to be only available in "Quarter Size Outline Packages" (QSOP) - the leads are very close together,not easy to experiment with.
Another alternative would be to use a MAX7219 display driver, this chip has a serial interface and an option to adjust the display brightness - something I may try later.
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