Datasheet

Application Information
13−9
SLLS535E − April 2008 TUSB6250
10. Because the CompactFlash storage card permits 8-bit data transfer only if a user issues a set feature command to put the device
in the 8-bit mode, there is no need to support it as long as the host driver prohibits such command. The IOCS16
pin at the
CompactFlash storage card reader side of the connector should be left open. See Section 13.4.2.2, IOCS16
, Pin 32 on the
ATA/ATAPI Connector, for a detailed explanation.
11. The CD1
and CD2 pins are card-detect pins that connect to ground on the CompactFlash storage card. They are used by the host
to determine that the CompactFlash storage card is fully inserted into its socket. A valid insertion is evaluated when both CD1
and
CD2
are detected as GND by the host.
13.5.3 Power-Up Sequence
Because the CompactFlash storage card powers up into PC card ATA modes (not true-IDE modes), to
configure the CompactFlash storage card into the true-IDE mode, the 50-pin CompactFlash socket must be
power cycled with the CompactFlash storage card inserted and the ATASEL
pin asserted. This also must be
accomplished when removing and reinserting the CompactFlash storage card when the CompactFlash
storage card reader power is on.
To achieve this required power-up sequence, the recommended approaches for the end-product custom
firmware to implement a CompactFlash storage card reader based on the TUSB6250 are described as
follows.
• The firmware can use the P2.0 pin as the power-up control signal to turn on/off the power to the
CompactFlash storage card. To ensure enough drive strength, the developer should use active-low as the
logic level to turn on the reader.
• After a power-up reset to the TUSB6250, the firmware can toggle the P2.0 pin to turn on the power to the
CompactFlash storage reader socket.
• Once CD1
and CD2 are both asserted (this means there is a CompactFlash storage card inserted), the
firmware must shut down the power to the CompactFlash storage card for a duration of about one second.
Thereafter, the firmware must turn the power back on. This sequence ensures the ATASEL
signal is
latched during the power cycle, such that the true-IDE mode is enabled for the CompactFlash storage
card.