C8051F331 Silicon Laboratories Inc, C8051F331 Datasheet - Page 191

• Manufacturer Part Number: C8051F331
• Description: IC 8051 MCU 8K FLASH 20MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F33xr

Specifications of C8051F331

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 17
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

19.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
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’.
PCA0CPLn
Write to
Reset
PCA0CPHn
Write to
0
1
ENB
ENB
W
M
P
1
6
n
x
C
O
M
E
n
Figure 19.5. PCA Software Timer Mode Diagram
PCA0CPMn
C
A
P
P
n
0 0
C
A
P
N
n
M
A
T
n
O
G
T
n
0 0
W
P
M
n
E
C
C
F
n
x
Enable
PCA
Timebase
C8051F330/1, C8051F330D
Rev. 1.2
PCA0CPLn
PCA0L
16-bit Comparator
PCA0CPHn
PCA0H
Match
C
F
C
R
PCA0CN
0
1
C
C
F
4
C
C
F
3
C
C
F
2
C
C
F
1
PCA Interrupt
C
C
F
0
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