kdb331: Using AMD G-Series Modules with Xtreme/CPU & Qseven Carriers

Title: Using AMD G-Series Modules with Xtreme/CPU & Qseven Carriers
Keywords: Xtreme/CPU, Qseven, AMD, G-Series, Modules Compatibility
Date: 2012/10/15
KDB: KDB-331
Revision: 0.01
Author: MF
Distribution: External

Introduction

This knowledge base entry discusses some limitations of using AMD G-series modules with Connect Tech’s QCG001 and QCG002 carriers.

Currently the following AMD G-Series based modules exist:

• conga-QAF
• SECO Quadmo747-Gseries
• MSC Q7-A50M

Display Limitations

VGA Not Supported

The QCG001 and QCG002 offer two display interfaces: LVDS and VGA.  The VGA interface is based on a SDVO (Serial Digital Video Out) to VGA converter IC (Chrontel CH7317B)

Intel Atom based modules expose an SDVO interface, while the AMG G-Series expose a HDMI interface

The Qseven interface specification reuses the same pins for the  HDMI / DisplayPort / SDVO interfaces (as shown in Table 1).

Therefore, the VGA interface will be unavailable when using the AMD series

Table 1: Qseven Pinout

Potential for damage to converter IC

In addition to the feature reduction, there is a potential for damage, when plugging the an AMD G-series module into a QCG001 or QCG002

• HDMI outputs are essentially being attached SDVO inputs
• Differential SDVO pairs are AC coupled differential signals. Therefore, there is not a specific DC signal level.

o    Differential signaling voltage V_DIFF = 800 mV (2x V_{TX DIFF P-P}=400mV)

• HDMI signals are DC coupled TMDS (Transition-minimized differential signaling); which is terminated to 3.3V.
• If the modules HDMI interface is idling at ground (0V), then there should be no long term damage to the CH7317B.
• If the modules HDMI interface is idling at 3.3V, there could be damage
• The CH7317B can tolerate up to 3.3V on its I2C interface (SDVO_CTRL_DAT and SDVO_CTRL_CLK).

o    The QCG001 and QCG002 have 5.6K pull-up resistors to 2.5V; the module will likely have 3.3V 100K pull-up resistors.  If this resistor value is less than 100K; there could be issues.

conga-QAF default settings

The conga-QAF has two Display Channels ,  Display Channel 0 Output defaults to LVDS & Display Channel 1 Output defaults to HDMI.  There is also a Boot Display Device setting, which defaults to Auto.

With carriers that only have LVDS display capabilities and are attached to a LVDS display with no EDID capabilities – the module might not boot with a display. If the LVDS display unit does not have EDID capabilities (identifying resolution and colors to the BIOS) ; the BIOS settings will need to be manually changed first in another carrier with HDMI capabilities.

For example, if using the conga-QEVAL carrier with the conga-LDVI (DVI to LVDS converter) – the BIOS settings Local Flat Panel Type had to be changed From Auto (default) To WXGA 1280×768 1×24.

End of KDB-331