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

  • Updated

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:

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

Pin SDVO DisplayPort HDMI
131 SDVO_BCLK+ DP_LANE3+ TMDS_CLK+
133 SDVO_BCLK- DP_LANE3- TMDS_CLK-
137 SDVO_GREEN+ DP_LANE1+ TMDS_LANE1+
139 SDVO_GREEN- DP_LANE1- TMDS_LANE1-
143 SDVO_BLUE+ DP_LANE2+ TMDS_LANE0+
145 SDVO_BLUE- DP_LANE2- TMDS_LANE0-
132 SDVO_INT+    
134 SDVO_INT-    
138 SDVO_FLDSTALL+ DP_AUX+  
140 SDVO_FLDSTALL- DP_AUX-  
144 SDVO_TVCLKIN+    
146 SDVO_TVCLKIN-    
149 SDVO_RED+ DP_LANE0+ TMDS_LANE2+
151 SDVO_RED- DP_LANE0- TMDS_LANE2-
153 HDMI_HPD#    
150 SDVO_CTRL_DAT
3.3V CMOS Open Drain		   HDMI_CTRL_DAT
3.3V CMOS Open Drain
152 SDVO_CTRL_CLK
3.3V CMOS Open Drain		   HDMI_CTRL_CLK
3.3V CMOS Open Drain
154   DP_HPD#  

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 VDIFF = 800 mV (2x VTX 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.

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

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