C8051F120DK Silicon Laboratories Inc, C8051F120DK Datasheet - Page 332

• Manufacturer Part Number: C8051F120DK
• Description: DEVKIT-F120/21/22/23/24/25/26/27
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F120DK

• Contents: Evaluation Board, Power Supply, USB Cables, Adapter and Documentation
• Processor To Be Evaluated: C8051F12x and C8051F13x
• Interface Type: USB
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F120
• Silicon Family Name: C8051F12x
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: C8051F120, 121, 122, 123, 124, 125, 126, 127
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1224

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