User manual

Advantech SOM-Express Design Guide
Chapter 5 Carrier Board Design Guidelines 61
5.6 Primary IDE0
SOM-Express provides one IDE interface.
5.6.1 Signal Description
Table 5-17 shows SOM-Express IDE signals, including pin number, signals, I/0 and
descriptions.
Table 5-17 IDE signals description
Pin Signal I/O Description
- IDE_D[0..15] I/O Bidirectional data to/from IDE device
D13,14,15 IDE_A[0..2] O Address lines to IDE device
D16 IDE_CS1# O IDE Device Chip Select for 1F0h to 1FF0h range
D17 IDE_CS3# O IDE Device Chip Select for 3F0h to 3FF0h range
D8 IDE_REQ I
IDE DMA Request for IDE Master. This is the input pin from
the IDE DMA request to do the IDE Master Transfer. It will
active high in DMA or Ultra-33 mode and always be inactive
low in PIO mode.
D10 IDE_ACK# O IDE device DMA Acknowledge
C13 IDE_IORDY I
IDE device I/O ready input
Pull low by the IDE device, active low
C14 IDE_IOR# O I/O ready line to IDE device
D9 IDE_IOW# O
I/O write line to IDE device
Data latched on trailing (rising) edge
D12 IDE_IRQ I Interrupt request from IDE device
D18 IDE_RESET# O Low active hardware reset (RSTISA inverted).
D77 IDE_CBLID# O
Input from off-module hardware indicating the type of IDE
cable being used. High indicates a 40-pin cable used for
legacy IDE modes. Low indicates that an 80 pin cable with
interleaved grounds is used. Such a cable is required for
Ultra-DMA 66, 100 and 133 modes.
5.6.2 Design Guidelines
5.6.2.1 Design Considerations
The IDE port can support two hard drives or other ATAPI devices. The two devices
on the port are wired in parallel, which is accomplished by plugging both drives into a
single flat ribbon cable equipped with two socket connectors. A jumper is typically
manually set on each device to set it for master or slave operation. If two devices are
used in the master/slave mode on the same IDE port, the IDE_CBLID# pins of both
devices must be connected together. These pairs of pins negotiate between the
master and slave devices. The devices may not function correctly unless these pins
are interconnected. If two devices are plugged into a single IDE cable, the cable will
interconnect the pins properly. If the two devices on one port are integrated on the
carrier board or plugged into separate connectors, care should be taken to tie the
corresponding pins together.