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3.2.5.4.1 ISA BUS LIMITATIONS
As already specified in the previous paragraph, the Intel® family of SoCs formerly coded as Bay trail do not support natively the ISA bus, which is required by ETX
specifications.
Therefore, this interface is realised using an LPC to ISA bridge (Fintek F85226AF), which causes the following limitations in using ISA Bus:
-
DMA transfers are not supported;
-
Memory Accesses are 8-bit at a time;
-
It is not possible to access to any area located under 1MB because of Bay Trail's limits;
-
Memory access in the 0xF0000000-0xF0FFFFFF window are translated into ISA access in the range 0xF0000000 ÷ 0xF0FFFFFF, which is a 16MB-1
window
-
Memory accesses in the area 0xF0000000-0xF00FFFFF, i.e. accesses in the lower 1MB area translated in addressable area, are handled like if the access
were above 1MB. This means that signals SMEMR# / SMEMW# will not change, only MEMR# and MEMW# will do.
3.2.5.5
Analog VGA interface (Connector X3 - CN8)
The SOCs used on ETX-A61 module can manage directly one analog display interface, which can be used for the connection of older VGA/CRT displays.
Signals dedicated to VGA interface are the following:
R: SOC's internal DAC's Red Signal video output.
G: SOC's internal DAC's Green Signal video output.
B: SOC's internal DAC's Blue Signal video output.
HSY: SOC's internal DAC's Horizontal Synchronization output signal, electrical level +5V_S.
VSY: SOC's internal DAC's Vertical Synchronization output signal, electrical level +5V_S.
DDCK: internal DAC's DDC Clock line for VGA displays detection. Output signal, electrical level +5V_S with 2K2Ω pull-up resistor.
DDDA: internal DAC's DDC Data line for VGA displays detection. Bidirectional signal, electrical level +5V_S with 2K2Ω pull-up resistor.
Please be aware that for the connection to external VGA displays, on the carrier board it is necessary to provide for filters and ESD protection.
ETX-A61
ETX-A61 User Manual - Rev. First Edition: 1.0 - Last Edition: 1.2 - Author: S.B. - Reviewed by G.G. Copyright © 2017 SECO S.r.l.
®
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