Specifications

Intel
®
810E2 Chipset Platform
R
68 Design Guide
3.13.1.1. Valid Codec Configurations
Table 20. Codec Configurations
Valid Codec Configurations Invalid Codec Configurations
AC(Primary) MC(Primary) + X(any other type of codec)
MC(Primary) AMC(Primary) + AMC(Secondary)
AMC(Primary) AMC(Primary) + MC(Secondary)
AC(Primary) + MC(Secondary)
AC(Primary) + AC(Secondary)
AC(Primary) + AMC(Secondary)
3.13.2. SPKR Pin Considerations
The effective impedance of the speaker and codec circuitry on the SPKR signal line must be greater than
50 kΩ. Failure to due so will cause the TCO Timer Reboot function to be erroneously disabled. SPKR is
used as both the output signal to the system speaker and as a functional strap. The strap function enables
or disables the “TCO Timer Reboot function” based on the state of the SPKR pin on the rising edge of
POWEROK. When enabled, the ICH2 sends an SMI# to the processor upon a TCO timer timeout. The
status of this strap is readable via the NO_REBOOT bit (bit 1, D31: F0, Offset D4h)
. The SPKR signal
has a weak integrated pull-up resistor (the resistor is only enabled during boot/reset). Therefore, it is
default state when the pin is a “no connect” is a logical one or enabled. To disable the feature, a jumper
can be populated to pull the signal line low (see figure). The value of the pull-down must be such that the
voltage divider caused by the pull-down and integrated pull-up resistors will be read as logic low. When
the jumper is not populated, a low can still be read on the signal line if the effective impedance due to the
speaker and codec circuit is equal to or lower than the integrated pull-up resistor. It is therefore strongly
recommended that the effective impedance be greater than 50 kΩ and the pull-down resistor be less than
7.3 kΩ.