Signal Descriptions
44 Datasheet
6.2 PCI Express* Based Interface Signals

Note: PCI Express* Ports 1, 2, and 3 signals are receive and transmit differential pairs.

Table 6-2. Memory Channel Miscellaneous

Signal Name Description
DDR_RESET_C01_N
DDR_RESET_C23_N
System Memory Reset: Reset signal from processor to DRAM devices on the
DIMMs. DDR_RESET_C01_N is used for memory channels 0 and 1 while
DDR_RESET_C23_N is used for memory channels 2 and 3.
DDR_SCL_C01
DDR_SCL_C23
SMBus clock for the dedicated interface to the serial presence detect (SPD) and
thermal sensors (TSoD) on the DIMMs. DDR_SCL_C01 is used for memory
channels 0 and 1 while DDR_SCL_C23 is used for memory channels 2 and 3.
DDR_SDA_C01
DDR_SDA_C23
SMBus data for the dedicated interface to the serial presence detect (SPD) and
thermal sensors (TSoD) on the DIMMs. DDR_SDA_C1 is used for memory
channels 0 and 1 while DDR_SDA_C23 is used for memory channels 2 and 3.
DDR_VREFDQRX_C01
DDR_VREFDQRX_C23
Voltage reference for system memory reads: DDR_VREFDQRX_C01 is used for
memory channels 0 and 1 while DDR_VREFDQRX_C23 is used for memory
channels 2 and 3.
DDR_VREFDQTX_C01
DDR_VREFDQTX_C23
Voltage reference for system memory writes: DDR_VREFDQTX_C01 is used for
memory channels 0 and 1 while DDR_VREFDQTX_C23 is used for memory
channels 2 and 3. These signals are not connected and there is no functionality
provided on these two signals. The signals are unused by the processor.
DDR{01/23}_RCOMP[2:0] System memory impedance compensation: Impedance compensation must be
terminated on the system board using a precision resistor.
DRAM_PWR_OK_C01
DRAM_PWR_OK_C23
Power good input signal used to indicate that the VCCD power supply is stable for
memory channels 0 and 1, and channels 2 and 3.

Table 6-3. PCI Express* Port 1 Signals

Signal Name Description
PE1A_RX_DN[3:0]
PE1A_RX_DP[3:0]
PCIe* Receive Data Input
PE1B_RX_DN[7:4]
PE1B_RX_DP[7:4]
PCIe Receive Data Input
PE1A_TX_DN[3:0]
PE1A_TX_DP[3:0]
PCIe Transmit Data Output
PE1B_TX_DN[7:4]
PE1B_TX_DP[7:4]
PCIe Transmit Data Output

Table 6-4. PCI Express* Port 2 Signals (Sheet 1 of 2)

Signal Name Description
PE2A_RX_DN[3:0]
PE2A_RX_DP[3:0]
PCIe Receive Data Input
PE2B_RX_DN[7:4]
PE2B_RX_DP[7:4]
PCIe Receive Data Input
PE2C_RX_DN[11:8]
PE2C_RX_DP[11:8]
PCIe Receive Data Input
PE2D_RX_DN[15:12]
PE2D_RX_DP[15:12]
PCIe* Receive Data Input
PE2A_TX_DN[3:0]
PE2A_TX_DP[3:0]
PCIe Transmit Data Output