C8051F124TB Silicon Laboratories Inc, C8051F124TB Datasheet - Page 332

• Manufacturer Part Number: C8051F124TB
• Description: MCU, MPU & DSP Development Tools With C8051F124 MCU
• Manufacturer: Silicon Laboratories Inc

Specifications of C8051F124TB

• Processor To Be Evaluated: C8051F12x and C8051F13x
• Interface Type: USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.4. 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 24.1.
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Where F
PCA0MD. The lower byte of the capture/compare module is compared to the PCA0 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.
Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn reg-
ister.
Important Note About Capture/Compare Registers : When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
332
W
M
P
1
6
n
0
PCA0CPMn
E
C
O
M
n
C
A
P
P
n
0 0 0
C
A
P
N
n
M
A
PCA
T
n
O
G
T
n
1
W
M
P
n
is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
E
C
C
F
n
0
PCA Timebase
Equation 24.1. Square Wave Frequency Output
Enable
Figure 24.7. PCA Frequency Output Mode
Comparator
PCA0CPLn
PCA0L
8-bit
F
sqr
=
---------------------------------------- -
2 PCA0CPHn
Rev. 1.4

match
Enable
Adder
8-bit Adder
F
PCA
Toggle
TOGn
0
1
CEXn
PCA0CPHn
Crossbar
Port I/O