C8051F311 Silicon Laboratories Inc, C8051F311 Datasheet - Page 209

• Manufacturer Part Number: C8051F311
• Description: IC 8051 MCU 16K FLASH 28MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F31xr

Specifications of C8051F311

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: POR, PWM, Temp Sensor, WDT
• Number Of I /o: 25
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 17x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

18.2.4. 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 18.1, 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 18.1. Square Wave Frequency Output
Figure 18.7. PCA Frequency Output Mode
W
P
M
1
6
n
x
E
C
O
M
n
PCA0CPMn
C
A
P
P
n
0 0 0
C
N
A
P
n
M
A
T
n
O
G
T
n
W
P
M
n
C
C
E
F
n
x
PCA Timebase
F
CEXn
Enable
=
Comparator
PCA0CPLn
---------------------------------------- -
2
Rev. 1.7
PCA0L

8-bit
PCA0CPHn
F
C8051F310/1/2/3/4/5/6/7
PCA
match
Enable
Adder
8-bit Adder
Toggle
TOGn
0
1
CEXn
PCA0CPHn
Crossbar
PCA
is the fre-
Port I/O
209