IDE Controller Configuration
The CPU’s onboard EIDE connector (CN10) supports several different drive speed modes, which are BIOS configurable. Supported drive modes will depend on whether a
Cable Modes
There are two types of cables that may be used for connecting drives to the EIDE connector: 40 conductor cables or 80 conductor cables. Depending on the cable used, different drive speeds are supported. A 40 conductor cable can be used for speeds up to UDMA Mode 2 (Ultra ATA/33).
In order to use drive speeds faster than UDMA Mode 2 (Ultra ATA/33), an 80 conductor cable is required. The BIOS can be configured to detect the presence of an 80 conductor cable. The 80 conductor cable adds a ground wire between each signal, and uses standard 40 pin connectors.
Cable Detection
Every time the cpuModule is powered on or a hardware reset is issued, the BIOS will automatically detect the presence of a 80 conductor cable connecting a device to CN10. The user selectable cable detection modes are described below.
Device and Host Mode
For this method, there is a capacitor on the CBLID pin at the CPU, and a
Host Determination of Cable Type
For this method of detection, the CPU reads the CPBLID pin, which determines if a
Device Detect
For device detect mode, the CPU issues a command to the device, which tells the CPU the fastest drive speed mode it can use. The CPU then sets the transfer mode to the fastest speed supported by the device.
WARNING When this cable detection method is enabled, the highest transfer speed supported by the device will be used regardless of whether a
Chapter 4: Using the cpuModule 67 |