Instruction Manual

Chapter 3 Hardware
ETX-PVR Reference Manual 39
17,
18
VCC DC Power – +5 volts +/-5%
19 OVCR* Over Current Detect – This signal indicates a USB over-current condition.
20 NC Not Connected
21 EXTSMI* External System Management Interrupt – This signal is provided by external
circuitry to initiate an SMI event with the ETX-PVR.
22
I
2
DAT This data line implements an I
2
C bus, which supports external slave devices
only. The I
2
C interface supports EEPROMs and other simple I/O devices.
23 SMBCLK System Management Bus Clock – This signal is used to support internal and
external SMBus devices, such as temperature and battery monitoring.
24 SMBDATA System Management Bus Data – This signal is used to support internal and
external SMBus devices, such as temperature and battery monitoring.
25 NC Not Connected
26 SMBALRT* System Management Bus Alert – This signal is used by SMBus devices to
signal an event on the SMBus.
27 NC Not Connected
28 DASP* Drive Active/Drive Present – This signal is time-multiplexed and indicates
the drive is present and active. If a Compact Flash is connected to the
baseboard, this signal must be routed to the DASP pin of any other device
connected to the IDE channel. May also be used for Master/Slave negotiation
on the IDE channel.
29 NC Not Connected
30 PIDE_CS3* Primary Chip Select 1 – Selects host-accessible Command Block Register.
31 NC Not Connected
32 PIDE_CS1* Primary Chip Select 0 – Selects host-accessible Command Block Register.
33,
34
GND Ground
35 PDIAG Passed Diagnostics – This signal is used for Master/Slave negotiation on the
IDE channel. It is asserted by the Slave to indicate to master that the slave has
passed its internal Diagnostics command. If a Compact Flash is connected to
the baseboard, this signal must be routed to the DASP pin of any another
device connected to the IDE channel.
May also be used to detect the presence of an 80-conductor IDE cable, which
is required for support of the DMA66 or DMA100 high-speed transfers.
36 PIDE_A2 Primary Drive Address Bus 2 – Used <0 to 2> to indicate which byte in the
ATA command block or control block (register) is being accessed.
37 NC Not Connected
38 PIDE_A0 Primary Drive Address Bus 0 – Refer to J4, pin-36, for more information.
39 NC Not Connected
40 PIDE_A1 Primary Drive Address Bus 1 – Refer to J4, pin-36, for more information.
41 BATLOW* Battery Low – This external signal to the ETX-PVR indicates when the
external battery is low.
42 NC Not Connected
43 NC Not Connected
Table 3-8. Complete X4 Interface Pin Signal Descriptions (J4) (Continued)