CPU documentation - General info

Clock settings - MCU Clock settings
- Oscillator frequency [MHz] - Frequency of the crystal, the RC oscillator or the external clock. The crystal should be in the range of 0.0001Hz-32MHz, the RC oscillator should be in the range of 2-12MHz and the external clock should be in the range of 0.0001-32MHz for 5-V control. The crystal should be in the range of 0.0001Hz-16MHz, the RC oscillator should be in the range of 2-12MHz and the external clock should be in the range of 0.0001-16MHz for 3-V control.
- Oscillator type - Type of the oscillator. There are two types of the oscillator, RC and crystal oscillator. The crystal oscillator must be used for MC68HC908xxx and RC oscillator must be used for MC68HRC908xxx. The crystal oscillator option also allows an external clock that can be driven directly into OSC1.
  There are 2 modes:
  - Crystal - Crystal oscillator (XTAL) - built-in oscillator that requires an external crystal or ceramic-resonator. This option also allows an external clock that can be driven directly into OSC1. The following items are displayed in this mode:
    - Clock input pin - Clock input properties.
      - Pin name - Clock input pin name (for information only).
    - Clock output pin - Clock output properties.
      - Pin name - Clock output pin name (for information only).
  - RC oscillator - RC oscillator (RC) - built-in oscillator that requires an external resistor-capacitor connection only. The selected oscillator is used to drive the bus clock, the SIM, and other modules on the MCU. The following items are displayed in this mode:
    - Clock input pin - Clock input properties.
      - The content is the same as in previous modes.
    - Oscillator clock output - Oscillator output clock settings. The output clock can be enabled only if the external RC oscillator is used as the MCU clock source.
      The following items are available only if the group is enabled (the value is "Enabled"):
      - Clock output pin - Oscillator output clock pin (for information only)
- Internal bus clock - The internal bus clock [MHz]. Maximum bus frequency is 8.0MHz for 5-V control and 4.0MHz for 3-V control.
- Low-power modes settings - Low-power modes settings.
  - STOP instruction enabled - STOP instruction enabled
    The following items are available only if the group is enabled (the value is "Enabled"):
    - Recovery from Stop Mode after - This property enables the CPU to exit the stop mode with a delay of 32 CGMXCLK cycles instead of a 4096 CGMXCLK cycle delay.
- CPU mode selection - CPU mode. This property is necessary for the correct CPU's internal timing.
  There are 2 modes:
  - Monitor mode - The following items are displayed in this mode:
    - PTB3 pin level - Logical value of PTB3 pin. The value on this pin is used by the processor when entering Monitor mode. For details see the datasheet of a particular device.
  - User mode - There are no items in this mode.
Maskable CPU interrupts - Enable/disable CPU maskable interrupts. This item modifies Interrupt Mask Bit I in Condition Code CPU register CCR.
Internal peripherals - Internal peripherals settings.
- I/O module - I/O ports' settings
  - PORT D - LED drive settings for all pins of PORT D.
    - Slow edge high current for PTD6 - This property is used to select slow edge high current for pin PTD6.
    - Slow edge high current for PTD7 - This property is used to select slow edge high current for pin PTD7.
- LVI module - This property enables/disables low voltage monitoring on the Vdd pin.
  The following items are available only if the group is enabled (the value is "Enabled"):
  - LVI Trip Voltage - Operating mode of the LVI module.
    
    There are 3 options:
    - 2.4V: For VDD=3V operation
    - 2.4V: For VDD=3V operation
    - 4V: For VDD=5V operation
CPU interrupts - Interrupts allocated by CPU bean
- Reset vector - Reset vector settings.
  - Interrupt - Interrupt associated with the reset vector (for information only)
  - ISR name - Name of the reset vector - routine, that initializes CPU after reset.
- SWI - This property enables/disables generation of SWI interrupt service routine.
  The following items are available only if the group is enabled (the value is "Enabled"):
  - Interrupt - Software Interrupt (for information only)
  - ISR name - Name of the interrupt service routine (ISR) invoked by this interrupt vector.
    The user code of the routine should handle all respective interrupt flags correctly.

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