Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual page 550

18.3.3.10 Major Modes
The USART supports a set of different I2S formats as shown in
these modes. MONO, JUSTIFY and DELAY in USARTn_I2SCTRL can be mixed and matched to create an appropriate format. MONO
enables mono mode, i.e. one data stream instead of two which is the default. JUSTIFY aligns data within a word on the I2S bus, either
left or right which can bee seen in figures
Right-Justified I2S Waveform on page
the word-select signal, or one bit-period after the edge.
Mode MONO
Regular I2S 0
Left-Justified 0
Right-Justified 0
Mono 1
The regular I2S waveform is shown in
I2S Waveform (Reduced Accuracy) on page
can be configured to 32-bit, 16-bit or 8-bit using FORMAT in USARTn_I2SCTRL. In the second figure, I2S data is transmitted with re-
duced accuracy, i.e. the data transmitted has less bits than what is possible in the bus format.
Note that the msb of a word transmitted in regular I2S mode is delayed by one cycle with respect to word select
USn_CLK
(word select)
USn_TX/
USn_CLK
(word select)
USn_TX/
A left-justified stream is shown in
after the edge on the word-select signal in contradiction to the regular I2S waveform where it comes one bit-period after.
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Figure 18.23 USART Left-Justified I2S Waveform on page 551
551. Finally, DELAY specifies whether a new I2S word should be started directly on the edge of
Table 18.9. USART I2S Modes
JUSTIFY
0
0
1
0
Figure 18.21 USART Standard I2S Waveform on page 550
550. The first figure shows a waveform transmitted with full accuracy. The wordlength
USn_CS
LSB MSB
USn_RX
Right channel
Figure 18.21. USART Standard I2S Waveform
USn_CS
MSB
USn_RX
Right channel
Figure 18.22. USART Standard I2S Waveform (Reduced Accuracy)
Figure 18.23 USART Left-Justified I2S Waveform on page
USART - Universal Synchronous Asynchronous Receiver/Transmitter
Table 18.9 USART I2S Modes on page
DELAY
1
0
0
0
Left channel
LSB
Left channel
Reference Manual
550, but it is not limited to
and Figure 18.24 USART
CLKPOL
0
1
1
0
and Figure 18.22 USART Standard
LSB MSB
Right channel
MSB
Right channel
551. Note that the MSB comes directly
Rev. 1.1 | 550