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Receiver Tab
9
SNLU159B – April 2014 – Revised September 2018
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Copyright © 2014–2018, Texas Instruments Incorporated
DS125DF1610EVM
Figure 9. Transmitter Tab
The DS125DF1610 output driver has 22 VOD level settings ranging from 150 mV to 1200 mV in 50 mV
increments. When the retimer is reset, the VOD level will return to the default value of 1000 mV. The
‘Edge Rate Select’ option allows the user to adjust the rise and fall time for the output signal, with the
default setting being the fastest rise/fall time.
The ‘Transmit FIR Control’ section consists of 3 FIR taps; pre-cursor, main-cursor, and post-cursor. The
pre-cursor and post-cursor taps emphasize the output voltage level to account for high frequency losses.
The main cursor primarily is used to balance the other two taps in order to sum to the appropriate
normalized sum value which based on the selected VOD setting. The pre-cursor, main cursor, and post-
cursor taps of the FIR filter are each adjusted on a scale of 0 – 63 but should be normalized based on the
selected VOD setting. Normalizing the taps can be performed either by selecting the Normalize before
applying checkbox, or by clicking the normalize taps button.
However, each of the 3 taps can be set to any of the 64 levels without being normalized. This is not
recommended as a starting point, but is a feature that can be utilized. To write the tap settings to the
register without normalizing them, ‘Normalize Before Applying’ must be deselected.
The ‘Normalize Taps’ push button will adjust the main cursor in order to sum the 3 taps to the value
predefined by the VOD setting the user selects. However, if the ‘Normalize Before Applying’ checkbox is
selected the 3 taps will be normalized when writing them to the register. The ‘Read Taps’ push button will
populate the current register settings for the pre, post, and main cursor taps into the corresponding fields.
‘Set Taps’ will write the pre, main, and post cursor settings into the register.
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Receiver Tab
The Receiver tab controls all the relevant functionality associated with the 16 receiver channels of the
DS125DF1610EVM. The ‘Signal Detect’ and ‘CDR Lock’ indicators are identical to the Transmitter Tab,
reflecting when a signal is detected or when the CDR locks. ‘Channel Select,’ ‘Update Time,’ and ‘Reset’
are all similar to the Transmitter Tab.