Kontron COMe Starterkit Eval T2 - Manual (Page 154)

COM Express Interfaces
Signal Pin Description I/O IDE40 IDE44 CF
CSEL 28 28 39
N.C. 20, 32 20, 32, 44 24, 40, 51,
52, 53, 54,
55, 56
39 (slave)
VCC_5V 41, 42, 13, 18, 36
2.24.2. IDE 40-Pin Header (3.5 Inch Drives)
To interface standard 3.5-inch parallel ATA drives, a standard 2.54mm, two row, 40-pin connector
in combination with a ribbon conductor cable is used. For slower drive speeds up to ATA33, a
normal 40-pin, 1.27mm-pitch conductor cable is sufficient. Higher transfer rates such as ATA66
and ATA100 require 80-pin conductor cables, where the extra 40 conductors are tied to ground to
isolate the adjacent signals for better signal integrity. The 80-pin cable assembly also ties pin 34
(IDE_CBLID#) on the 40-pin header to GND. If IDE_CBLID# is sampled low by the Module's
BIOS, it assumes that the proper high-speed cable is present and sets up the drive parameters
accordingly. Jumper settings on the IDE devices determine Master/Slave configuration. The
drive activity LED is driven by the Module's pin A28 (COM Express pin ATA_ACT#).
Figure 62 : Connector type: 40 pin, 2 row 2.54mm grid female
2.24.3. IDE 44-Pin Header (2.5 Inch and Low Profile Optical Drives)
To interface standard 2.5-inch parallel ATA drives, as well as low profile optical drives, a
standard 2.0mm, two row, 44-pin connector in combination with a 44-conductor ribbon cable
is used. For slower drive speeds up to ATA33, a normal 44-conductor, 1.0mm-pitch cable is
sufficient. Higher transfer rates such as ATA66 and ATA100 require special handling as
ground isolated cables like those commonly used for 3.5” ATA devices do not exist for this
interface. Simulation as well as testing should be used to determine if an application specific
44-pin cable interface can support ATA66 and ATA100 speeds. Items to be taken into
consideration include cable length, placement in the system, folds and routing. Because 44-
conductor cables have no method of indicating their transfer rate capability, IDE_CBLID#
must be controlled on the Carrier Board or by using BIOS setup. For 44-pin ATA devices, the
drive activity LED is driven by pin 39 of the header.
2.24.4. CompactFlash 50 Pin Header
CompactFlash (CF) cards with DMA capability require that the two signals 'IDE_REQ' and
'IDE_ACK#' are routed to the CF card socket on the COM Express Carrier Board. If this is not
done then some DMA capable CF cards may not work because they are not designed for non
DMA mode. For more information about this subject, refer to the data sheet of the CF card or
contact your CF card manufacturer.
CF socket pin 39 (CSEL#) is connected to a jumper to select Master or Slave configuration. If
jumpered low, the drive is configured for Master mode. This provides the ability to perform a
CompactFlash boot.
2.24.5. IDE / CompactFlash Reference Schematics
This reference schematic shows a circuitry implementing an IDE connector and a CF card socket
that is DMA capable.
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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