PIC12F675 Tutorial 7: A Servo controller driving a standard servo motor using serial port command

Quick Solutions to Questions related to Servo Controller:

• How is the servo position controlled?
  You type a text command into a serial terminal like Hyperterminal to set the position.
• What hardware components are required for the circuit?
  The project uses a solderless breadboard, a serial port connector, a MAX232 transceiver, and a 1k resistor.
• Does the system generate continuous servo signals?
  No, the project does nothing until you type in commands, though it maintains a zero position signal.
• What clock source provides the timing?
  The internal 4MHz clock serves as the timing source for the circuit.
• Can the maximum pulse width values be changed?
  Yes, the software limits values to 1.0ms and 2.0ms, but these limits can be changed in the software.
• How does the software handle multitasking?
  It services two processes at once: serial port input monitoring and servo motor output.
• Which timer generates the 20ms repeat rate?
  Timer 0 interrupt is used to generate the 20ms repeat rate for the servo controller.
• How are accurate timed pulses generated?
  Accurate pulses are generated using Timer 1 interrupts which are enabled when Timer 0 triggers.
• What happens when Timer 0 triggers?
  When Timer 0 triggers, it enables the Timer 1 interrupt and sets the servo pin high.
• What occurs when Timer 1 triggers?
  When Timer 1 triggers, the servo pin is set low to complete the exact output pulse.