Datasheet

pri_tx_en_n
pri_tx
25 50 75
Symbol Period
pri_tx_en_n
pri_tx
Symbol Period
25 50 75
pri_tx_en_n
pri_tx
25 50 75
Symbol Period
Frame Frame
Interframe
Period
Frame FrameD DD D
Interframe
Period
Frame Frame Frame
DAC161P997
SNAS515E –JULY 2011–REVISED OCTOBER 2013 www.ti.com
Inter-Frame Period
The fastest DAC update rate is achieved when Master sends the valid frames back to back, Continuous Mode, at
the fastest Baud rate. This, however, results in the least power efficient implementation.
SWIF is designed to operate in the Burst Mode as well, where the valid frames are separated by the inter-frame
periods that do not carry any data. The inter-frame period can be occupied by a stream of idle ‘D’ or ‘L’ symbols.
Sending the ‘D’ symbol in the inter-frame period provides continuous verification of integrity of the data link. The
device by default monitors the activity of the SWIF link, and if the activity ceases the ERRB flag is asserted. See
CONFIG2 and Error Detection and Reporting.
Sending the ‘L’ in the inter-frame period results in the transmission line being inactive (transition-free) except
when the data frames are being transmitted. This is the most power efficient implementation of SWIF link, but it
does not facilitate link integrity reporting. To avoid ERRB being asserted due to the channel inactivity,
CONFIG2.CHANNEL should be cleared.
Symbol Set
The digital data encoding scheme is outlined in the table below. The signal names in the table correspond to the
nodes shown in Figure 25.
The signal waveforms due to a random symbol stream are shown in Figure 20.
Table 1. Symbol Set Table
Character Mnemonic SWIF Symbol Comments
• Occupies one symbol period
• Transmit from Master only
• 25% duty-cycle square waveform
“0”
• Terminates LOW
• Occupies one symbol period
• Transmit from Master only
• 75% duty-cycle square waveform
“1”
• Terminates LOW
• Occupies one symbol period
• Transmit from Master only
• 50% duty-cycle square waveform
“D”
• Terminates LOW
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