C8051F581-IMR Silicon Labs, C8051F581-IMR Datasheet - Page 338

• Manufacturer Part Number: C8051F581-IMR
• Description: 8-bit Microcontrollers - MCU 50MIPS 128kB 8kB SPI
• Manufacturer: Silicon Labs

Specifications of C8051F581-IMR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

C8051F58x/F59x
29.3.4. 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 PCA1 clocks to count before the
output is toggled. The frequency of the square wave is then defined by Equation 29.1.
Where F
PCA1MD. The lower byte of the capture/compare module is compared to the PCA1 counter low byte; on a
match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA1CPLn.
Frequency Output Mode is enabled by setting the ECOM1n, TOG1n, and PWM1n bits in the PCA1CPMn
register. Note that the MAT1n bit should normally be set to 0 in this mode. If the MAT1n bit is set to 1, the
CCFn flag for the channel will be set when the 16-bit PCA1 counter and the 16-bit capture/compare regis-
ter for the channel are equal.
338
Note: A value of 0x00 in the PCA1CPHn register is equal to 256 for this equation.
PCA1CPLn
Write to
Reset
PCA1CPHn
PCA
Write to
is the frequency of the clock selected by the CPS12 – 0 bits in the PCA1 mode register,
0
ENB
ENB
1
Equation 29.1. Square Wave Frequency Output
W
M
P
1
6
1
n
x
PCA1CPMn
E
C
O
M
1
n
Figure 29.7. PCA1 Frequency Output Mode
C
A
P
P
1
n
0 0 0
C
A
P
N
1
n
M
A
T
n
1
O
G
T
1
n
W
M
P
1
n
E
C
C
F
1
n
x
PCA1 Timebase
F
CEXn
Enable
=
------------------------------------------ -
2 PCA1CPHn
Rev. 1.2
Comparator
PCA1CPLn
PCA1L

8-bit
F
PCA
match
Enable
Adder
8-bit Adder
Toggle
TOG1n
0
1
CEXn
PCA1CPHn
Crossbar
Port I/O