PIC16F887-E/P Microchip Technology, PIC16F887-E/P Datasheet - Page 140

• Manufacturer Part Number: PIC16F887-E/P
• Description: IC PIC MCU FLASH 8KX14 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F887-E/P

• Core Size: 8-Bit
• Program Memory Size: 14KB (8K x 14)
• Mfg Application Notes: Intro to Capacitive Sensing Appl Notes Layout and Physical Design Appl Note
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 35
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 368Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Package: 40PDIP
• Device Core: PIC
• Family Name: PIC16
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 2.5|3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 35
• Interface Type: I2C/SPI/USART
• On-chip Adc: 14-chx10-bit
• Number Of Timers: 3
• Processor Series: PIC16F
• Core: PIC
• Data Ram Size: 368 B
• Maximum Clock Frequency: 20 MHz
• Maximum Operating Temperature: + 125 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 53273-916
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM164123, DM164120-3, DV164122
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DVA18XP400 - DEVICE ADAPTER 18F4220 PDIP 40LD
• Lead Free Status / Rohs Status: Details

PIC16F882/883/884/886/887
11.6.2.1
In the Full-Bridge mode, the P1M1 bit in the CCP1CON
register allows users to control the forward/reverse
direction. When the application firmware changes this
direction control bit, the module will change to the new
direction on the next PWM cycle.
A direction change is initiated in software by changing
the P1M1 bit of the CCP1CON register. The following
sequence occurs prior to the end of the current PWM
period:
• The modulated outputs (P1B and P1D) are placed
• The associated unmodulated outputs (P1A and
• PWM modulation resumes at the beginning of the
See Figure 11-12 for an illustration of this sequence.
FIGURE 11-12:
DS41291F-page 138
in their inactive state.
P1C) are switched to drive in the opposite
direction.
next period.
Note 1: The direction bit P1M1 of the CCP1CON register is written any time during the PWM cycle.
P1A (Active-High)
P1B (Active-High)
P1C (Active-High)
P1D (Active-High)
Signal
2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle. The
Direction Change in Full-Bridge
Mode
modulated P1B and P1D signals are inactive at this time. The length of this time is (1/Fosc) • TMR2 prescale
value.
EXAMPLE OF PWM DIRECTION CHANGE
Pulse Width
Period
(1)
The Full-Bridge mode does not provide dead-band
delay. As one output is modulated at a time, dead-band
delay is generally not required. There is a situation
where dead-band delay is required. This situation
occurs when both of the following conditions are true:
1.
2.
Figure 11-13 shows an example of the PWM direction
changing from forward to reverse, at a near 100% duty
cycle. In this example, at time t1, the output P1A and
P1D become inactive, while output P1C becomes
active. Since the turn off time of the power devices is
longer than the turn on time, a shoot-through current
will flow through power devices QC and QD (see
Figure 11-10) for the duration of ‘t’. The same
phenomenon will occur to power devices QA and QB
for PWM direction change from reverse to forward.
If changing PWM direction at high duty cycle is required
for an application, two possible solutions for eliminating
the shoot-through current are:
1.
2.
Other options to prevent shoot-through current may
exist.
The direction of the PWM output changes when
the duty cycle of the output is at or near 100%.
The turn off time of the power switch, including
the power device and driver circuit, is greater
than the turn on time.
Reduce PWM duty cycle for one PWM period
before changing directions.
Use switch drivers that can drive the switches off
faster than they can drive them on.
Pulse Width
(2)
Period
© 2009 Microchip Technology Inc.