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Colour Maximite Microcomputer, Pt.2

Building the unit and using its new sound & colour features

By Geoff Graham

IN DESIGNING THE Colour Maximite, we have been careful to specify parts that can be easily sourced. So if you want to “go it alone” without a kit, that option is always open to you. The two custom parts, the PCB and a programmed PIC32 chip, can be purchased directly from the SILICON CHIP Partshop.

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Alternatively, if you want to source the PIC32 chip yourself, you must also have access to a suitable programmer. In that case, the PIC32 chip can be purchased direct from Microchip, Element14 or some other supplier. You must be careful to choose the correct part number as there are two 100-pin packages, one measuring 12 x 12mm and the other 14 x 14mm. We designed the PCB to suit the latter, to make it easier to solder, so be sure to purchase the 14 x 14mm package (with the /PF suffix), as specified in the parts list.

The SD card connector is a little more difficult. Every manufacturer seems to have their own footprint for this connector. We designed the PCB so that it could accommodate a number of different footprints but we have only tested the Hirose DM1A connector which is reasonably popular and available from Element14 and others.

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The high-density VGA connector is also available in a number of different footprints so we have selected the most popular. This version has an overall depth of 22mm from front to back.

The 10µF SMD capacitor connected to pin 85 of the PIC32 must be a ceramic type. Don’t try to substitute a tantalum or (heaven forbid) an electrolytic here, as this component is critical to ensure that the PIC32’s CPU starts and runs correctly.

As mentioned last month, regulator REG2 (TC1262) was selected for its low drop-out voltage and accuracy. You can substitute another device with the same pin-out but you should ensure that it has a drop-out voltage of 0.8V or less, otherwise the Colour Maximite could intermittently crash.

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