Design Benefits of the MI/O Extension Solution

Design Benefits of the MI/O Extension Solution
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Design Benefits of the MI/O
Extension Solution
By Chechia Hsu, R&D Manager and Sandy Chen, Product Manager, Advantech
ystem integration is not an easy task, making system
integration easier is the goal of most clients. By using
the MI/O Extension solution, we can help customers retain
domain knowledge and design their own extension modules,
making mechanical designs more compact with fewer system
parts, and centralize thermal designs to improve reliability.
The MI/O Extension provides a flexible and functional
design for single-board embedded systems, and it provides
new definitions for mechanical planning and cooling design.
It has also made breakthroughs with regard to the limited
expandability of conventional single-board designs and can
extend I/O modules in a flexible manner as well as drive
market demand for various vertical applications with a more
efficient approach.
MIOe Pinouts and Functions
MIOe is diverse enough to meet the requirements of most
applications because it is an integrated interface standard
defined by Advantech. It includes a wide variety of interfaces
such as DP (DisplayPort), PCIe, USB, LPC, SMBus, Audio Line
Out and Power, which will meet customer requirements in
terms of system integration. Compared with ordinary singleinterface standards such as PCI, PCIe and PC/104, MIOe is
in a position to provide better integration for more diverse
applications in order to satisfy the demands from different
MIOe has the ability to support up to 4 Giga LAN from 4 PCIe
x1, and multiple RS232/422/485 ports with added super I/O
from the LPC. On the SMBus, a SMBus-to-GPIO IC converter
can be used to produce a GPIO signal, which can be used
to control the switching between RS232 and RS485. If it is
necessary to come up with additional specifications such as
isolation, these functional designs can be used on the same
MIOe module. In addition, since power to the MIOe module
can be supplied directly from the MI/O Extension main CPU
board, there is no need to design a separate power zone on the
module, which significantly reduces the design complexity
of the module. This is something a single-interface standard
cannot achieve, whereas with a MIOe module it is quite
simple to integrate these types of applications together.
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How MIOe can lower the design barrier for
From the design perspective of circuit and layout
The interfaces selected in the design of MIOe are based on
the knowledge and experiences provided over the years.
Also, these are interfaces recognized as being future
industry trends. The goal of MIOe connector is to incorporate
as many interfaces as possible within a limited number of
pins. The number of signals in a single interface is small,
which implies relatively simple circuits and design layout,
which in turn lowers the design barrier of the MIOe module.
Take the design of the SMBus as an example. The SMBus
contains only two wires and this simplifies circuit design
and traces in layout. Furthermore, the absence of high-speed
signals results in fewer things to consider in design layout,
which helps substantially reduce the development duration
and cost.
Although other interfaces, such as USB and PCIe, involve
high-speed signals, the number of these signals is small and
the circuit design remains simple. In terms of layout, one
must still pay attention to length and impedance. However,
these high-speed signals allow trace lengths of up to 10
inches or longer (depending on the chipset employed) and
can resolve layout issues stemming from spatial constraints.
For example, a USB connector can be placed wherever it
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is actually needed and does not have to be in proximity
to the MIOe connector due to length limitations. A longer
permitted trace length usually implies better compatibility,
and USB or PCIe signals on the MIOe module will not cause
compatibility problems due to different trace lengths.
From the perspective of design cost
A MI/O Extension single board can be used individually,
and the design requirements for MIOe modules emerge
only when the motherboard lacks I/O functions, However,
for markets with specific applications, it is difficult to
fulfill certain specifications with standard board solutions.
Therefore, most specific applications will require customized
solutions. From the perspective of customers, a higher
forecast, larger NRE, and longer development time will be
required; if a customized solution is necessary, it may also
be difficult to have complete control over retaining certain
domain knowhow.
The design of MIOe is similar to the concept of the I/O module.
The design and development capabilities of the module can
be primarily achieved by the customers themselves and
the barrier mentioned above can be lowered. The most
complex part, normally power design, has also already
been integrated into the MI/O Extension board. If the entire
module consumes only 25W of power, there is no need to
design a separate power unit. Resolving these problems will
substantially reduce development costs.
From the perspective of power supply design
The planning of power supply for MIOe is as follows: The CPU
board supplies 12V and 5V to the MIOe module. The CPU
board can provide at least 25W of power to the MIOe module,
which is sufficient for most applications. If the MIOe module
requires more than 25W of power, the power architecture
can be changed to one power supply providing electricity to
the CPU board and MIOe module simultaneously, as shown
in the following diagram.
Power supply planning for MIOe can meet the requirements
of low- and high-power consumption applications alike. For
low-power applications, the MIOe module can utilize the
power supplied by the CPU board directly. Furthermore, the
timing of power on the MIOe module is directly controlled
by the CPU board and this prevents system boot failure due
to incorrect power timing control on the MIOe module so it
can reduce design effort, cost and development schedule.
Power Supply
CPU Board
MIOe Module
Three example for GPIO application
High Cost/High Speed
Another characteristic of MIOe is that it is possible to
incorporate a wide variety of devices. For example, USB and
PCIe connect with a large number of applications, such as
Giga LAN or wireless LAN on the PCIe interface, and COM
and storage devices to the USB interface to name a few. In
order to realize the GPIO, one can utilize a PCIe-to-GPIO
converter, but the cost will be relatively high, even though a
faster GPIO can be achieved with PCIe’s higher bandwidth.
On the other hand, converting the SMBus to GPIO will result
in substantially lower costs; the downside being lower speed.
The response time can be measured in milliseconds, and
the specific design solution will depend on the particular
application and requirements of the customer.
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From the perspective of reference documents
For customers adopting the MIOe design architecture,
Advantech has prepared the following technical documents:
The MI/O Extension SPEC and MIOe Design Guide. These
allow design teams to consult information in the documents
directly, including pinouts, mechanical integration and
cooling design. Advantech has evaluation boards and
standard MIOe modules so that MIOe functions can be
verified quickly. Customers can develop boards with the
required capabilities rapidly, which makes system design
and integration more methodical.
Devices For MIOe Functional Signals
DP (DisplayPort):
DP (DisplayPort) is an application interface related to screen
display, and it has become a mainstream technology in
current and future platforms. Past standards such as SDVO
and LVDS may only be supported in certain platforms, and
current trends indicate that these interfaces may not be
supported in the future or will fall out of favor with users.
Using DP in conjunction with a controller, various types of
interfaces such as HDMI, LVDS and eDP can be created.
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PCIe x 1:
PCIe accommodates high-speed signals and uses a relatively
large amount of bandwidth. MIOe provides 4 PCIe x1 slots,
which can be configured as PCIe x2 or PCIe x4 according
to bandwidth or application requirements (depending on
chipset specifications) and can meet the needs of applications
with higher bandwidth requirements, such as high-speed
transmission applications. PCIe x1 has been widely adopted
in Giga LAN, PCIe-to-SATA conversions, PCIe-to- USB2.0/
USB 3.0 conversions, and it can be adapted directly into a
miniPCIe interface.
USB 2.0 / 3.0:
MIOe retains 3 x USB 2.0 interfaces, or 1 x USB 2.0 plus 1 x
USB 3.0 (depending on chipset specifications). The USB is a
more mature interface than others in terms of storage device,
including USB Flash, USB-to- CF card and USB-to-SD card
conversion, or it can be linked directly with connectors.
LPC (Low Pin Count):
The LPC interface can be used to create the RS232/422/485
serial ports, print port, floppy, TPM, hardware monitor, GPIO,
and other basic functions. Designs that incorporate CPLD
or FPGA will be more practical with respect to customers’
actual application requirements and can be customized.
As shown in the diagram below, customers can modify the
firmware to accommodate their desired functionality and
quantity, such as GPIO, digital to analog, analog to digital,
and RAM.
SMBus (System Management Bus):
The SMBus is currently the most widely adopted and also lowcost interface. ICs that provide this interface can be found in
all types of analog signal applications, e.g. digital to analog,
analog to digital, and voltage/current/temperature sensing.
In addition, digital signal applications such as GPIO, Clock
and EEPROM have also been widely deployed on CPU boards
for quite some time.
Audio Line Out:
MIOe provides an audio line-out signal for a selection of
appropriate audio amplifiers based on the actual application
required. Even if an audio amplifier is present, its
specifications most likely won’t meet the requirements of
all customers. MIOe leaves the flexibility to customers, who
will be able to determine the suitable amplifier to include
based on their application.
Mechanical Design Advantages of the MI/O
The idea for MI/O Extension’s innovative form factor is
primarily the result of consideration for system integration.
They include concepts for simplifying mechanical parts, and
approaches for easy assembly, plus how to avoid possible
system integration problems that have been encountered in
the past.
Integrated design for wiring
Cables are used when assembling chassis. Too much wiring
will require wrapping and may result in airflow and cooling
problems. Therefore in the design of the MI/O Extension form
factor, the amount of internal wiring is minimized and wires
with a uniform style have been adopted to improve usability
and avoid the complexities associated with wrapping.
Unified Connector Location:
The connectors such as COM, SATA and Audio are
designed to be close to the edge of the board. This is
conducive to system integration applications, allowing for
easy wiring and bundling as well as convenient centralized
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Centralized thermal design
The cooling design of the MI/O Extension enables system, thermal and mechanical engineers to arrange the desired layout
during project development and design without giving special considerations to the locations of heat spots on the CPU board
or requiring separate cooling designs. For single board applications, it is also unnecessary to reserve heat dissipation space
under the CPU board for heat-generating components, which makes slimmer system designs possible. Components that
generate large amounts of heat are concentrated in one top side on the board, and with the Heatspreader cooling solution or
customized cooling modules can easily achieve a fanless system design.
Thermal Solution
Diagram showing MI/O-Compact in conjunction
with the MIOe module.
MI/O Extension SBC
MIOe Module
Diagram showing MI/O-Ultra in conjunction with
the MIOe module.
Unified expansion
The module expansion area can be found underneath the MI/O Extension board. Module expansions include the outwardfacing CFast, PCIe Mini Card and the MIOe module, which enables customers to design their own expansion features,
and mechanical engineers only need to create holes or design the base board modules for system integration purposes.
In addition, under the board there are no components that generate large amounts of heat, and therefore there are fewer
restrictions on the selection of expansion modules.
The MI/O Extension form factor functional divisions
provide simpler system assembly and cooling integration.
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Advantages of cooling design in the MI/O
With system integration, a serious problem that customers
often encounter is heat generated by the system. There
are a large number of components besides the CPU board
within a system, for example power supply, hard drive,
and panel inverter. Plus, other peripherals may be sources
of heat themselves, or may be affected by heat-generating
components. If the system’s mechanical components are
poorly designed, excessive heat may cause problems, or
perhaps it may be necessary to employ peripherals of higher
quality which cost more, to ensure the stability of the
In addition, chipsets generate part of their energy into heat
during operation, which will in turn affects reliability and
lifespans. For example, if the environment temperature rises
by 10 degrees, its lifespan will be reduced by half. Therefore,
adoption of a single-unit, integrated heat sink can improve
the heat exchange and conduction efficiency within and
outside of the system.
Single-surface heat generation reduces problems with
heat beneath the board
The centralized heat design of the CPU board can also
prevent issues that may arise from high heat-generating
components on the other side affecting other peripherals. If
the heat-generating components are scattered on different
PCB surfaces, then components on the opposite side of the
heat sink will not be able to take advantage of the heat sink
and dissipate heat appropriately. There is also less space
underneath the board and air flow can become a problem, as
the heat that accumulates under the board cannot dissipate
Maximized heat dissipation area
The form factor of MI/O Extension is designed to include
a fixed cooling area, and therefore the overall area of heat
dissipation is maximized, which increases cooling effects
Reduction of overall system height
With an optional heat spreader, the surface can be applied
directly to the top cover of the chassis for full-surface heat
conduction. This reduces the height of the system that may
otherwise have required cooling fins, and achieves optimal
cooling effects.
Thermal simulation diagram of centralized heat source design
(e.g. MI/O Extension)
Thermal simulation diagram of non-centralized (dispersed) heat source
Advantages of implementing centralized cooling:
With Advantech’s MI/O Extension cooling design, all heatgenerating components, including the CPU, southbridge,
memory, Power PMIC, Clock GEN and selected Active IC,
are centrally located on the same side of the PCB, so that
customers only need to consider the cooling design for a
single surface, which simplifies mechanical design.
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Advantech has gained considerable experience during its
many years of involvement in the industrial computer sector.
Taking future application trends and feedback from the
market into consideration, and looking at the issues from the
perspective of providing solutions to customers’ problems,
the company has introduced the industry’s pioneering MI/O
Extension technology. In addition to providing an optimized
cooling and mechanical design to solve system integration
problems, the technology has retained the maximum level
of I/O expandability, enabling customers to realize their
desired modular product designs with the fewest resources
available. It also allows customers to utilize Advantech’s
single-board computers with MI/O Extension to create more
solutions and gain new business opportunities with more
flexible designs.
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