· Self-programmability: These devices can write to their own program memory spaces under internal software control. By using a bootloader routine located in the protected Boot Block at the top of program memory to Break Microcontroller PIC18F4220 Binary, it becomes possible to create an application that can update itself in the field.
· Enhanced CCP Module: In PWM mode, this module provides 1, 2 or 4 modulated outputs for controlling half-bridge and full-bridge drivers. Other features include Auto-Shutdown for disabling PWM outputs on interrupt or other select conditions and Auto-Restart to reactivate outputs once the condition has cleared.
Addressable USART: This serial communication module is capable of standard RS-232 operation using the internal oscillator block, removing the need for an external crystal (and its accompanying power requirement) in applications that talk to the outside world.
· 10-bit A/D Converter: This module incorporates programmable acquisition time, allowing for a channel to be selected and a conversion to be initiated without waiting for a sampling period and thus, reduce code overhead.
· Extended Watchdog Timer (WDT): This enhanced version incorporates a 16-bit prescaler, allowing a time-out range from 4 ms to over 2 minutes, that is stable across operating voltage and temperature.
The EC and ECIO Oscillator modes require an external clock source to be connected to the OSC1 pin. There is no oscillator start-up time required after a Power-on Reset or after an exit from Sleep mode. In the EC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic by Break Microcontroller PIC18F4220 Binary.
For timing insensitive applications, the “RC” and “RCIO” device options offer additional cost savings. The RC oscillator frequency is a function of the supply voltage, the resistor (REXT) and capacitor (CEXT) values and the operating temperature.
In addition to this, the oscillator frequency will vary from unit to unit due to normal manufacturing variation. Furthermore, the difference in lead frame capacitance between package types will also affect the oscillation frequency, especially for low CEXT values.
The user also needs to take into account variation due to tolerance of external R and C components used. Figure 2-6 shows how the R/C combination is connected. In the RC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic.