Design Check: LVDS Messages

When you check your design, the Interface Designer applies design rules to your LVDS settings. The following tables show some of the error and warning messages you may encounter and explains how to fix them.

lvds_rule_clkout_mode (error)

Message Serial clock name must be configured in clock output mode
To fix When you are using the clkout mode, you need to specify the serial clock pin name.
Message Parallel clock name must be configured in clock output mode
To fix When you are using the clkout mode, you need to specify the parallel clock pin name.
Message Parallel clock division <value> is out of range <min>-<max>
To fix Parallel clock division factor has to be within specified range (min=1, max=2).
Message Parallel clock division <value> is not an integer
To fix Parallel clock division factor has to be an integer.

lvds_rule_output_mode (error)

Message Output name must be configured in data output mode
To fix Specify a valid pin name.
Message Parallel clock name must be configured in data output mode
To fix When you are using non-bypass mode, you need to specify the parallel clock pin name.
Message Serial clock name must be configured in data output mode
To fix When you are using non-bypass mode, you need to specify the serial clock pin name.

lvds_rule_resource (error)

Message Resource name is empty
To fix You need to choose a valid resource.
Message Resource <string> is not a valid LVDS (Tx/Rx) device instance
To fix You need to choose a valid LVDS (Tx/Rx) resource.

lvds_rule_resource_excluded (error)

Message Resource <resource> is excluded in Package Planner. Please use another resource
To fix The pins for the affected resource have been excluded in the Package Planner, and cannot be assigned. Remove the excluded setting in the Package Planner or choose another resource.

lvds_rule_rx_alt_conn (error)

Message Connection type <type> is not supported by the resource
To fix If you want to use the alternate funciton of an LVDS block, you need to choose a resource that supports it. You can filter for resources by alternate function in the Resource Assigner.
Message The resource only supports normal connection type
To fix You need to choose the normal connection type or assign a different resource that supports the connection type you want to use. You can filter for resources by alternate function in the Resource Assigner.

lvds_rule_alt_conn (warning)

Message Connection type <type> must be used by valid PLL
To fix The LVDS block is connected to a PLL clock input but is the resource you assigned does not support the pll_clkin alternate function. Choose a different resource that supports it. You can filter resources by alternate function in the Resource Assigner.
Message Connection type <type> cannot be used on an unbonded resource
To fix You get this error if the resource you choose is not available in the FPGA/package combination you are using. Choose another resource.
Message pll_clkin connection to PLL clock source not being used in <instance>
To fix The LVDS block is set to be a PLL reference clock (pll_clkin connection type) but the PLL is not configured to use it. Make sure that the clock you are choosing in the PLL is associated with this LVDS RX's resource.
Message pll_clkin connection to PLL clock source but none of the external clock source in PLL <instance> is selected
To fix The LVDS block is set to be a PLL reference clock (pll_clkin connection type) but the PLL is not configured to use it. In the PLL block, choose external or dynamic as the Clock Source and make sure that the clock you are choosing is associated with this LVDS RX's resource.
Message pll_clkin connection to PLL clock source but PLL Clock source on <instance> is set to core
To fix The LVDS block is set to be a PLL reference clock (pll_clkin connection type) but the PLL is not configured to use it. In the PLL block, choose external or dynamic as the Clock Source and make sure that the clock you are choosing is associated with this LVDS RX's resource.

lvds_rule_rx_clock (error)

Message Serial and parallel clocks cannot be the same clock
To fix You cannot use the same clock for both the serial (FASTCLK) and parallel (SLOWCLK) clocks.
Message Serial clock name is not a PLL output clock
To fix Use a PLL output clock as the serial (FASTCLK) clock.
Message Parallel clock name is not a PLL output clock
To fix Use a PLL output as the parallel (SLOWCLK) clock.
Message Serial and parallel clocks are not from the same PLL instance
To fix You need to use the same PLL to generate both clocks.
Message One of the clock frequencies is 0
To fix Set a valid output clock frequency.
Message Serial clock frequency has to be <float> times faster than parallel clock
To fix Make sure that the PLL output clock frequencies are set correctly.
serial clock frequency = parallel clock frequency * (serialization / 2)

lvds_rule_rx_clock (warning)

Message Serial clock <string> phase shift has to be 90 degrees
To fix Adjust the phase shift for the serial clock to be 90 degrees.

lvds_rule_rx_config (error)

Message Input name must be configured
To fix Specify a valid pin name.
Message Serial clock name must be configured
To fix When you are using the LVDS deserializer (deserialization width greater than 1), you need to specify the serial clock pin name.
Message Parallel clock name must be configured
To fix When you are using the LVDS deserializer (deserialization width greater than 1), you need to specify the parallel clock pin name.
Message Serialization must be configured
To fix When you are using the LVDS deserializer, you need to set the serialization width,

lvds_rule_rx_distance (error)

Message These Rx LVTTL must be placed at least 2 pairs away from LVDS <name> in order to avoid noise coupling from LVTTL to LVDS: <violated list>
To fix When using LVDS pins as GPIO, make sure to leave at least 2 pair of unassigned LVDS pins between any LVDS and LVDS used as LVDS RX in the same bank. This separation reduces noise.

lvds_rule_rx_pll_refclk (error)

Message Serial clock name is not a PLL output clock
To fix Use a PLL output clock as the serial (FASTCLK) clock.
Message Parallel clock name is not a PLL output clock
To fix Use a PLL output as the parallel (SLOWCLK) clock.

lvds_rule_rx_pll_refclk (warning)

Message Serial clock is expected to be from the following PLL instance: <resource>
To fix Only a specific PLL instance can drive the LVDS RX clocks. Change the PLL to use that resource.
Message PLL driving the serial clock should have its reference clock from an LVDS in pll_clkin connection type
To fix The PLL's reference clock needs to be driven by a specific resource. Create an LVDS RX block and set the Connection Type to pll_clkin. Then use that block as the PLL reference clock.
Message Parallel clock is expected to be from the following PLL instance: <resource>
To fix Only a specific PLL instance can drive the LVDS RX clocks. Change the PLL to use that resource.
Message PLL driving the parallel clock should have its reference clock from an LVDS in pll_clkin connection type
To fix The PLL's reference clock needs to be driven by a specific resource. Create an LVDS RX block and set the Connection Type to pll_clkin. Then use that block as the PLL reference clock.

lvds_rule_tx_clock (error)

Message Serial and parallel clocks cannot be the same clock
To fix You cannot use the same clock for both the serial (FASTCLK) and parallel (SLOWCLK) clocks.
Message Parallel clock <name> phase shift has to be 0 degree
To fix Set the Parallel clock <name>'s phase shift to 0 degree
Message Serial clock name is not a PLL output clock
To fix Use a PLL output clock as the serial (FASTCLK) clock.
Message Parallel clock name is not a PLL output clock
To fix Use a PLL output as the parallel (SLOWCLK) clock.
Message Serial and parallel clocks are not from the same PLL instance
To fix You need to use the same PLL to generate both clocks.
Message One of the clock frequencies is 0
To fix Set a valid output clock frequency.
Message Serial clock frequency has to be <float> times faster than parallel clock
To fix Make sure that the PLL output clock frequencies are set correctly.
serial clock frequency = parallel clock frequency * (serialization / 2)
Message Serial clock <string> phase shift has to be 45 degrees
To fix Adjust the phase shift for the serial clock to be 45 degrees. When serialization width is 3, serial clock phase shift has to be 45 degree.
Message Allowed serial clock (<name>) phase shift values: 45, 90, 135 degrees
To fix Set to the allowed phase shift values when serialization width is not 3.

lvds_rule_tx_distance (error)

Message These Tx LVTTL must be placed at least 2 pairs away from LVDS <name> in order to avoid noise coupling from LVTTL to LVDS: <violated list>
To fix When using LVDS pins as GPIO, make sure to leave at least 2 pair of unassigned LVDS pins between any LVDS and LVDS used as LVDS TX in the same bank. This separation reduces noise.

lvds_rule_clkout_ser_disabled (error)

Message Output clock name must be configured in clock output mode with serialization disabled
To fix Specify the output clock name.

lvds_rule_rx_pll_feedback (warning)

Message PLL <pll_slow_inst_name> driving the LVDS Rx clock sources should have its feedback mode set to core for optimized performance
To fix Set feedback mode of the PLL to core for better performance.

lvds_rule_rx_parallelclk_to_refclk_freq (error)

Message Parallel clock frequency (<value>MHz) to PLL reference clock frequency (<value>MHz) ratio is expected to be an integer
To fix Specify an integer value.

lvds_rule_alt_config (error)

Message <resource> can only be used as an LVDS PLL reference clock
To fix If LVDS Rx does not have pout (data) pins, then only can be used as a reference clock (i.e. GPIOB_RX_CLK).