Table 10: LCPLL Attributes (cont'd)
Attributes
Type
Description
SDM_CFG0[15:0]
16-bit
Reserved. Use the recommended value from the Wizard.
Bit Name
Address
Description
SDM_WIDTHSEL
[10:9]
This attribute sets the denominator of the fractional part of
the feedback divider:
2'b00
: 24 bits.
2'b01
: 20 bits.
2'b10
: 16 bits.
2'b11
: Reserved.
SDM_CFG1
16-bit
Reserved. Use the recommended value from the Wizard.
SDM_CFG2
16-bit
Reserved. Use the recommended value from the Wizard.
SDM_SEED_CFG0
16-bit
Reserved. Use the recommended value from the Wizard.
SDM_SEED_CFG1
16-bit
Reserved. Use the recommended value from the Wizard.
A_SDM_DATA_CFG0
16-bit
Reserved. Use the recommended value from the Wizard.
A_SDM_DATA_CFG1
16-bit
Reserved. Use the recommended value from the Wizard.
Reset and Initialization
The GTM transceiver must be initialized after device power-up and configuration before it can be
used. The GTM transmitter (TX) and receiver (RX) can be initialized independently and in parallel
as shown in the following figure. The GTM transceiver TX and RX initialization comprises three
steps:
1. Initializing the associated PLL driving TX/RX
2. Initializing the TX and RX datapaths (PMA + PCS)
The TX and RX in the GTM transceiver receive the clock through the LCPLL in the transceiver's
own Dual. In the power-on initialization sequence, the LCPLL used by the TX and RX must be
initialized first. The LCPLL used by the TX and RX is reset individually and its reset operation
independent from TX and RX resets. The TX and RX datapaths must be initialized only after the
associated LCPLL is locked.
Chapter 2: Shared Features
UG581 (v1.0) January 4, 2019
Virtex Ult GTM Transceivers
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