Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual page 452

S0
'b00
+1
-1
-1
S3
'b10
-1
-1
+1
S2
'b11
OVSQUAD1X mode
Transitions between States
and S1 updates the counter
Figure 16.3. PCNT State Transitions for Different Oversampling Quadrature Decoder Modes
The counter direction can be read from the DIR bit in PCNTn_STATUS register. Additionally, the DIRCNG interrupt in the PCNTn_IF is
generated when the direction change is detected. When a change is detected, the DIR bit in the PCNTn_STATUS register must be read
to determine the new direction.
In the oversampling quadrature decoder modes, the maximum input toggle frequency supported is 8KHz. For frequencies of 8KHz and
higher, incorrect decoding occurs. The different decoding modes and the counter updates are further illustrated by
Oversampling Quadrature Decoder 1X Mode on page
453 and Figure 16.6 PCNT Oversampling Quadrature Decoder 4X Mode on page
S0IN
S1IN
CNT
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Relationship between inputs and its state
STATE
+1
+1
S3
S1
'b10
'b01
+1
+1
Transitions between States
S0
and S1
452,
Period > 125 us
4 5
3
Figure 16.4. PCNT Oversampling Quadrature Decoder 1X Mode
S1IN S0IN
S0 0 0
S1 0 1
S2 1 1
S3 1 0
S0
'b00
+1
-1
-1
S1
'b01
-1
-1
+1
S2
'b11
OVSQUAD2X mode
S0
and between S3 and S2
updates the counter
Figure 16.5 PCNT Oversampling Quadrature Decoder 2X Mode on page
453.
6
6
5
Reference Manual
PCNT - Pulse Counter
S0
'b00
+1
+1
-1
-1
S3
S1
'b10
'b01
-1
-1
+1
+1
S2
'b11
OVSQUAD4X mode
All state transitions updates the
counter
Figure 16.4 PCNT
4 3
Rev. 1.1 | 452