SMARC T335x Carrier Board Hardware Design Guide, Document Revision 1.2
application skew budget. A variety of shielding options are available.
Ribbon cables are a cost effective and easy solution. Even though they are
not well suited for high-speed differential signaling they do work fine for very
short runs. Most cables will work effectively for cable distances of <0.5m.
The cables and connectors that are to be utilized should have a differential
impedance of 100
Ω
±15%. They should not introduce major impedance
discontinuities that cause signal reflections.
For more information about this subject refer to the 'LVDS Owners Manual
Chapter 6' available from National Semiconductor (
http://www.national.com
).
2.4.8. Routing Consideration for LVDS
See
SMARC T335X
layout guide for trace routing guidelines and the
SMARC
specification for more information about this subject and the '
LVDS
Owner’s Manual Chapter 3
' from National Semiconductor
(http://www.national.com) for more information about this subject.
2.5 SD/SDIO Interface
The
SMARC
module form factor features one 4-bit SD/SDIO interfaces as
standard interface and can be a boot device.
SDIO (Secure Digital I/O) provides an easy to implement solution for
high-speed data I/O combined with low power consumption. SDIO cards are
fully compatible with SD memory cards. This includes mechanical, electrical,
power, signaling and software compatibility.
SDIO hosts are able to drive SD cards and MMC (MultiMediaCards) as well as
SDIO cards that provide functions such as Ethernet or WLAN, GPS receivers,
Bluetooth, modems etc.