C8051F330DR Silicon Labs, C8051F330DR Datasheet - Page 196

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C8051F330DR

Manufacturer Part Number
C8051F330DR
Description
8-bit Microcontrollers - MCU 8kB 10ADC
Manufacturer
Silicon Labs
Datasheet

Specifications of C8051F330DR

Product Category
8-bit Microcontrollers - MCU
Core
8051
Data Bus Width
8 bit
Maximum Clock Frequency
25 MHz
Program Memory Size
8 KB
Data Ram Size
768 B
On-chip Adc
No
Operating Supply Voltage
2.7 V to 3.6 V
Package / Case
QFN-20
Mounting Style
SMD/SMT
Data Rom Size
128 B
Interface Type
I2C, SPI, UART
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Number Of Programmable I/os
17
Number Of Timers
4
On-chip Dac
No
Processor Series
C8051
Program Memory Type
Flash
Factory Pack Quantity
1500
Supply Voltage - Max
3.6 V
Supply Voltage - Min
2.7 V
C8051F330/1/2/3/4/5
19.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate a pulse width modulated (PWM) output on its associ-
ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the
output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be
reset (see Figure 19.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare high byte
(PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register
enables 8-Bit Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 19.4.
Important Note About Capture/Compare Registers : When writing a 16-bit value to the PCA0 Cap-
ture/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’.
Using Equation 19.4, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
200
PCA0CPLn
Write to
Reset
PCA0CPHn
Write to
0
ENB
ENB
1
W
P
M
1
6
n
0
Figure 19.8. PCA 8-Bit PWM Mode Diagram
O
M
E
C
n
PCA0CPMn
C
A
P
P
n
0 0 x 0
C
A
P
N
n
Equation 19.4. 8-Bit PWM Duty Cycle
M
A
T
n
O
G
T
n
W
DutyCycle
M
P
n
E
C
C
F
n
x
PCA Timebase
Enable
=
PCA0CPHn
Comparator
PCA0CPLn
Rev. 1.7
PCA0L
-------------------------------------------------- -
8-bit
256 PCA0CPHn
Overflow
256
match
S
R
SET
CLR
Q
Q
CEXn
Crossbar
Port I/O

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