Instructions and Requirements for booting MicroDesktop with EOMA68-A20
This are instructions for the very early (first 5) prototype MicroDestkop units.
you will need:
- a revision 1.0 microdesktop PCB
- a revision 2.2 EOMA68-A20 PCB marked "MODEL DS113", "VER 2.2", "2014-08-20"
- a PSU with anywhere between 7 and 21v, pin+ 5.5mm bog-standard jack
- a Micro-HDMI cable (TYPE D. NOT Type C, B or A).
- an ethernet cable
- potentially a USB UART (one that supports TTL levels NOT RS232. something using an FTDI chip works great)
- a 4-port USB hub (preferably powered)
- keyboard, mouse.
- a piece of ESD/non-conducting material
- a DHCP server somewhere on a LAN
- to put the SD card into the LOWER slot (on the micro-desktop board)
- to plug the USB hub into the LOWER USB socket. BE CAREFUL. hold the socket (not the PCB) when putting it in: the socket is NOT PROPERLY SOLDERED DOWN. put pressure on the back of the USB socket when pushing from the other side with the USB plug, in other words.
- DO NOT plug in the power
- to plug in the CPU Card (out of its case is ok if you put the anti-static material under it)
- MAKE SURE that the CPU is facing upwards
- MAKE SURE that when looking straight down there is an equal gap left and right
- MAKE SURE that the CPU Card is plugged into both sets of pins
- i.e. not the top row plugged into the bottom set of pins or the bottom row plugged into the top set of pins
what i tend to do is look side-on (into the connector, staring directly at all the pins) then put the card in so that it is 2-5 mm away from the pins, then visually line up the back of the top left socket hole with the top left pin. if you look at the connector from the back (along the PCB, over the top of all the components) you'll see what i mean: the metal spring-loaded sides of each pin can be clearly seen at the back of the 68-pin connector, and you can use those to visually line up on the pins.
ONLY when you are ABSOLUTELY sure that you cannot see 34 pins from the top, nor 34 pins from the bottom, and are ABSOLUTELY sure that the gap left and right between CPU Card PCB and the sides of the socket are equal, THEN plug in the power.
power comes up straight away. be careful plugging in the Micro-HDMI and the SD card. there is ESD protection diodes on the Micro-HDMI but it is not a good idea to "wiggle" it. there however are NO ESD diodes on the SD Card's socket. i'm not doing anything special for that but i just mention it in case.
i have set up the OS to connect to my VPN if it achieves internet access: this way if there are any problems i can sort them out remotely (except networking ones of course).
the root password is "password" and it is possible to happily log in at the wdm display manager as root.
the HDMI monitor should respond within 15 or so seconds, and not long after wdm will be up (around 5 more seconds).
anything beyond that and it's borked, you'll need to diagnose by soldering on a USB-UART
soldering on a USB UART