2 Dec 2013: First revision routing

This Mini Desktop PC has progressed very rapidly not only because it is such a simple board but also because it is a hybrid combination of both the Flying Squirrel and the Router. The PCB size is around 4.2 x 4.0 in with the USB, Ethernet and VGA connectors overhanging the edge of the PCB by about another 0.25in.

Connectors are arranged as follows: Top left is Ethernet, then downwards comes two dual-stacked USB2 connectors and the VGA port. Across the top is SATA and the 2.5in 44-pin expansion header. Top right is the reset switch, then under that is a standard 5.5mm power jack (2.1mm centre pin), then the EOMA68 socket and below that is a standard 3.5mm stereo headphone jack.

All connectors are TOP side, with very few components underneath. Technically it would be possible to make a Desktop PC of the same size as the EOMA68 CPU Card however this would be a separate product and would require a special case design with stand-off supports for the PCB.

Components - which are taken from the Flying Squirrel and the Router product - include a CM108AH, two FE1.1 USB Hubs, an Atmel ATSAM4SB (64QFN), a Richtek RT8288A as the main Power Regulator (5V @ 4A output, with anywhere between 6V and 21V input), a TDA2822 for 0.5W per channel stereo speaker output, a couple of SY6280 USB power regulators, a SY8008B for 3.3v power regulation and an Atmel I2C EEPROM AT24C64 for EOMA68 compliance.

In essence this is a very simple board. RGB/TTL conversion to VGA has been kept to an absolute minimum by having buffer ICs straddle the EOMA68 RGB/TTL outputs within a few mm. All other high-speed signals are differential pairs. The design is nearly 100% complete: the 3.3v, 5.0v and USB power planes need to be done and it is ready to go.

Posted Mon 02 Dec 2013 20:11:55 GMT