c8051t617 Silicon Laboratories, c8051t617 Datasheet - Page 193

• Manufacturer Part Number: c8051t617
• Description: Mixed Signal Byte-programmable Eprom Mcu
• Manufacturer: Silicon Laboratories

19.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the out-
put is toggled. The frequency of the square wave is then defined by Equation 19.1, where F
quency of the clock selected by the CPS2-0 bits in the PCA mode register, PCA0MD.
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
The lower byte of the capture/compare module is compared to the PCA counter low byte; on a match,
CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Fre-
quency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn register.
PCA0CPLn
Write to
Reset
PCA0CPHn
Write to
0
1
ENB
ENB
Equation 19.1. Square Wave Frequency Output
Figure 19.7. PCA Frequency Output Mode
W
M
P
1
6
n
x
O
M
E
C
n
PCA0CPMn
C
A
P
P
n
0 0 0
C
A
P
N
n
M
A
T
n
O
G
T
n
W
M
P
n
E
C
C
F
n
x
PCA Timebase
F
CEXn
Enable
=
Comparator
PCA0CPLn
Rev. 0.3
---------------------------------------- -
2
PCA0L
×
8-bit
PCA0CPHn
F
C8051T610/1/2/3/4/5/6/7
PCA
match
Enable
Adder
8-bit Adder
Toggle
TOGn
0
1
CEXn
PCA0CPHn
Crossbar
PCA
is the fre-
Port I/O
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