Embedded Open Modular Architecture/EOMA-200

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  • Dimensions: 100mm x 65mm PCB in a 103 x 68 x 16mm case
  • Pinouts: 4 50-pin B2B connectors providing 200 mandatory pins
  • Extensibility: 30mm x 14mm front-facing panel space and 2nd 65mm x 14mm front-facing panel
  • Power provision: 5V @ 3.5A and 3.3V @ 3.5A (29 Watts total)
  • Target uses: Small Desktop systems, Micro servers, Smart NAS Home Servers, Digital Signage, Industrial PCs, Education and R&D purposes.


With many standards providing 200 or more pins, the differentiator which makes EOMA-200 worthwhile is that all other standards are bare PCB factory-only modules with optional sizes and optional functions. These factors combine to make other standards realistically installable only by experts or technical engineers with knowledge of ESD precautions and the full details of the available options.

The EOMA-200 modular standard is designed to be user-installable in mass-volume appliances. There are no options on the pinouts, thus making the purchasing decisions and the installation easy for the average person. Instead, options for extensibility are offered via two front-facing panels, in exactly the same way that standard ITX and ATX motherboards provide a standard front-facing area. One is of size 30mm x 14mm, and the other is of size 65mm x 14mm. The 65mm panel is sufficient to fit up to 4 Ethernet ports, or up to 8 USB2/3 ports, an HDMI connector, eSATA etc. The 30mm panel is intended but not limited to having an on-board MiniPCIe slot behind it, such that WIFI SMA connectors can be put into the 30mm panel.

Preliminary pinouts

Total pinouts summary

These pinouts are NOT OPTIONAL. However, within the majority of the interfaces is the ability to down-level negotiate or provide less than the full set of functionality. For example: if a particular SoC or CPU does not have USB3, then the USB3 pins can be left out and USB2 only provided. Likewise for PCIe: if a particular SoC or CPU does not have full 4-lane PCI Express capability then a 2x or even a 1x lane can be provided. Likewise also for the SD/MMC which can reduce down as far as 4 pins (in SPI mode); I2S as well can reduce down to 5 pins; Ethernet can down-level negotiate to 100mb/sec or even 10mb/sec.

HDMI: 19
USB3 1: 8
USB3 2: 8
USB3 3: 8
USB-OTG 4: 5
I2C 0: 2
I2C 1: 2
I2S: 8
SPI: 5
5V : 7
3.3V : 7
GND: 19
SDMMC 1: 12
PCIe4x: 20
Gig Eth: 8
GPIO: 24
UART 1: 2
UART 2: 4
Total: 200


  • PCI Express pinouts: [1]
  • SD/MMC description of 4-pin SPI mode: [2]

Connector 1

This block contains HDMI, Ethernet, I2S, I2C and 6 GPIO. HDMI provides 5V power; this must be taken into consideration. HDMI also has 5 additional GND pins, bringing the total GND pins to 9 for this connector. It also has 3 power pins (2 5V and 1 3.3V)

1-19: HDMI
20: GND
21-28: Gig Eth
29: GND
30-37: I2S
38-39: I2C 1
40-41: 2 5V
42: GND
43: 1 3.3V
44: GND
45-50: 6 GPIO


  • I2S 8 pins: MCLK, BCLK, LRCK, DO0, DO1, DO2, DO3, DI

Connector 2

This connector is primarily for PCI Express. 4 of the 6 GPIOs are dedicated to PCI Express management, and the I2C lane is also intended for connection to the PCI Express bus. Also provided is SD/MMC. There are 6 GND pins in total on this connector, and 4 3.3v power pins.

1-24: PCIe4x + 4 GND
25-26: I2C 0
27-38: SDMMC
41: GND
42-43: 4 3.3V
44: GND


  • SD/MMC: [3]
  • SD/MMC 1-bit, 4-bit and 8-bit modes: [4]
  • eMMC: [5]
  • eMMC pinouts: CMD, CLK, RST, D0-D7. 1 extra pin reserved for Card Detect (if needed)

Connector 3

This connector provides 24-pin RGB/TTL, SATA, 2 UARTs and 6 GPIO pins. It also has 4 GND pins and 2 5V power lines. UART 1 is a 2-pin RS232, whilst UART2 provides TX, RX as well as CTS and RTS.

1-28: RGB/TTL
29: GND
30-33: SATA
34: GND
35-38: UART 2
39-40: UART 1
41: GND
42-43: 2 5V
44: GND
45-50: 6 GPIO

Connector 4

This connector is primarily for USB, although it also provides an SPI port and 6 GPIO pins. There are also 7 GND pins in total and 3 5V power lines.

1-7: 1 USB3 + 1 GND
8-14: 2 USB3 + 1 GND
15-21: 3 USB3 + 1 GND
22-28: 4 USB3 + 1 GND
29-32: 5 USB-OTG (Tx, Rx, ID) + 1 GND
33-37: SPI
38: GND
39-41: 3 5V
42: GND
45-50: 6 GPIO


  • USB3 pinouts [6]

Example EOMA-200 PC

The example below shows how a small Desktop PC can be created. This example has:

  • HDMI output
  • 1 USB3
  • 4 USB2
  • 2 Gigabit Ethernet
  • 1 eSATA
  • SD/MMC
  • Micro-SD
  • Micro-USB
  • Mini PCIe with a combined Bluetooth 4 and 802.11N 300mb/sec WIFI card
  • Standard Audio connectors
  • DC Power input jack