PIC18F4520-I/P Microchip Technology Inc., PIC18F4520-I/P Datasheet - Page 152

• Manufacturer Part Number: PIC18F4520-I/P
• Description: 40 Pin, 32 KB Flash, 1536 RAM, 36 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F4520-I/P

• A/d Inputs: 13-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 36
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 32K Bytes
• Ram Size: 1.5K Bytes
• Speed: 40 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F2420/2520/4420/4520
16.4.2
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR1L contains
the eight MSbs and the CCP1CON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The PWM duty cycle is
calculated by the following equation.
EQUATION 16-2:
CCPR1L and CCP1CON<5:4> can be written to at any
time, but the duty cycle value is not copied into
CCPR1H until a match between PR2 and TMR2 occurs
(i.e., the period is complete). In PWM mode, CCPR1H
is a read-only register.
The CCPR1H register and a 2-bit internal latch are
used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM opera-
tion. When the CCPR1H and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or two bits
of the TMR2 prescaler, the CCP1 pin is cleared. The
maximum PWM resolution (bits) for a given PWM
frequency is given by the following equation.
TABLE 16-2:
DS39631A-page 150
Timer Prescaler (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>) •
PWM Frequency
PWM DUTY CYCLE
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
T
OSC
• (TMR2 Prescale Value)
2.44 kHz
FFh
16
10
9.77 kHz
Preliminary
FFh
10
4
39.06 kHz
EQUATION 16-3:
16.4.3
The P1M1:P1M0 bits in the CCP1CON register allow
one of four configurations:
• Single Output
• Half-Bridge Output
• Full-Bridge Output, Forward mode
• Full-Bridge Output, Reverse mode
The Single Output mode is the standard PWM mode
discussed in Section 16.4 “Enhanced PWM Mode”.
The Half-Bridge and Full-Bridge Output modes are
covered in detail in the sections that follow.
The general relationship of the outputs in all
configurations is summarized in Figure 16-2.
Note:
FFh
10
1
PWM Resolution (max) =
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
PWM OUTPUT CONFIGURATIONS
156.25 kHz
3Fh
1
8
 2004 Microchip Technology Inc.
312.50 kHz
1Fh
log
1
7
(
log(2)
F
F
PWM
OSC
416.67 kHz
)
bits
6.58
17h
1