C8051F521-IMR Silicon Labs, C8051F521-IMR Datasheet - Page 203

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C8051F521-IMR

Manufacturer Part Number
C8051F521-IMR
Description
8-bit Microcontrollers - MCU 8KB 12ADC 125C 10Pin MCU
Manufacturer
Silicon Labs
Datasheet

Specifications of C8051F521-IMR

Product Category
8-bit Microcontrollers - MCU
Rohs
yes
Core
8051
Data Bus Width
8 bit
Maximum Clock Frequency
25 MHz
Program Memory Size
8 KB
Data Ram Size
256 B
On-chip Adc
Yes
Package / Case
DFN-10
Mounting Style
SMD/SMT
A/d Bit Size
12 bit
A/d Channels Available
6
Interface Type
SPI, UART
Maximum Operating Temperature
+ 125 C
Minimum Operating Temperature
- 40 C
Number Of Programmable I/os
6
Number Of Timers
3
On-chip Dac
No
Processor Series
C8051
Program Memory Type
Flash
Factory Pack Quantity
1500
Supply Voltage - Max
2.7 V, 5.25 V
Supply Voltage - Min
2 V, 2.7 V
19.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare mod-
ule defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches
the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted
low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match inter-
rupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn
register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help
synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by
Equation 19.3.
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 19.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0.
19.3. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 2. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH2) exceed a specified
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE bit set in the PCA0MD register, Module 2 operates as a watchdog timer (WDT). The
Module 2 high byte is compared to the PCA counter high byte; the Module 2 low byte holds the offset to be
used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some
PCA registers are restricted while the Watchdog Timer is enabled.
W
M
P
1
6
n
1
PCA0CPMn
C
O
M
E
n
C
A
P
P
n
0 0 0 0
C
N
A
P
n
M
A
T
n
PCA Timebase
O
G
T
n
W
M
P
n
E
C
C
F
n
0
Enable
PCA0CPHn
Equation 19.3. 16-Bit PWM Duty Cycle
PCA0H
DutyCycle
Figure 19.9. PCA 16-Bit PWM Mode
16-bit Comparator
PCA0CPLn
PCA0L
=
Rev. 1.4
---------------------------------------------------- -
65536 PCA0CPn
Overflow
match
65536
S
R
SET
CLR
Q
Q
C8051F52x/F53x
CEXn
Crossbar
Port I/O
203

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