GD32W51x User Manual
1003
If the serial channel uses the Manchester interface, the clock loss detection starts after the
first successful synchronization of the Manchester code, and the external serial input data
(DATAINx signal) is compared with the serial output clock (CKOUT signal). The serial input
data must change every 2 ckout signal cycles, otherwise clock loss event will be generated.
The timing of clock loss is shown in the figure below.
Figure 30-5. Clock loss detection timing diagram
1
0
0
?
?
SITYP[1:0]=2
SITYP[1:0]=3
Recovered
clock
Recovered
data
D
A
T
A
IN
x
Manchester clock loss
timing
CKOUT
Up to 2cycles
Data flow
unchanged
CKLF
Clock loss event
CKOUT
CKIN
CKLF
SPI clock loss
event
Up to 8 cycles
SPI clock loss
timing
Note:
the maximum rate of Manchester encoded data stream must be less than the clock
output CKOUT signal.
Channel pin redirection
Channel pin redirection means that the pins of serial channel 0 can be configured as the pins
of channel 1, that is, channel 0 can read information from the DATAIN1 and CKIN1 pins. Pin
redirection is used to sampling audio data of PDM microphone. The audio signal of PDM
microphone includes data and clock signal. The data is divided into left/right channel data.
The left channel data is sampled at the rising edge of clock signal, and the right channel data
is sampled at the falling edge of clock signal.
When PDM microphone data stream is input into serial channel, its configuration process is
as follows:
1.
Select the HPDF serial channel 1 of PDM microphone data stream input.
2.
Write 0 to CHPINSEL bit of channel 1 in HPDF_CHxCTL register, and input pin of channel