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Figure 5. Intel® HD Audio Front Panel Analog Header Motherboard Schematic
2.3.5.1.1 Dongle Presence Detection
The PRESENCE# signal is used to inform BIOS that an Intel® HD Audio dongle is connect to the
motherboard. This signal should be wired to a system GPI and BIOS should poll the GPI to check
for the presence of the Intel® HD Audio dongle in the system during POST. Nominal motherboard
pullup value of 10 k is required on this signal.
2.3.5.1.2 Jack Detection
Jack detection is accomplished with the use of the jack detection resistors Rjd_port1 and Rjd_port2.
The value of these resistors depends on which CODEC ports are tied to the Intel® HD Audio analog
header ports. Motherboard designers should consult the Intel® HD Audio specification for more
information on the assignment of these values for a give codec port.
2.3.5.2 Intel® HD Audio Front Panel Connections
Figure 6 shows a Intel® HD Audio front panel dongle implementation and a Intel® HD Audio front
panel analog header schematic. The front panel dongle consists of JACK1 and JACK2, and their
Front Panel Legacy I/O
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associated signal pins, connected directly to their respective pins on the dongle stake pin header.
The SENSE_SEND signal is split and routed through the PORT1 and PORT2 isolated switches.
The other contact of each isolated switch, are routed to their respective sense return signals,
SENSE1_RETURN and SENSE2_RETURN. This functionality, together with the Rjd_PORT1
and Rjd_PORT2 resistors on the motherboard as shown in Figure 5, informs the audio driver of
jack insertion or removal, which is necessary for dynamic re-taking of the front panel jacks.
Finally, a 1 k pulldown is required on the PRESENCE# pin to signal BIOS that the Intel® HD
Audio front panel dongle is connected to the system.