'Unit' related articles 1

  1. 2007/07/02 MC68HC05K3 - HCMOS Microcontroller Unit
• Low-cost HC05 core
• 16-pin PDIP, 16-pin SOIC package, or 20-pin SSOP
• 928 bytes of user ROM, including eight bytes of user vectors
• 64 bytes of user RAM
• Low-power operation at 1.8 V — VDD minimum (EEPROM read only)
• 128 bits of personality EEPROM (not memory mapped) programmed using CPU software or with on-chip serial programming ROM
• On-chip charge pump for in-circuit programming of the personality EEPROM at 2.7 to 5.5 Vdc
• 8-bit free-running timer
• 4-stage selectable real-time interrupt generator
• 10 bidirectional input/output (I/O) lines including:
– 8-mA sink capability on four I/O pins (PA7–PA4)
– Mask option for software programmable pulldowns on all I/O pins
– Mask option for port interrupts on four I/O pins (PA3–PA0) (keyboard scan feature)
• IRQ interrupt hardware mask, flag bit, and request bit
• Mask option for sensitivity on IRQ interrupt (edge- and level-sensitive or edge-sensitive only)
• On-chip oscillator (mask options for crystal/ceramic resonator oscillator with internal 2-MW resistor and 2-pin or 3-pin resistor capacitor (RC) oscillator)
• Mask option for reduced startup delay time with RC oscillator options
• Mask option for computer operating properly (COP) watchdog system
• Power-saving stop mode and wait mode instructions
• Mask option to convert STOP instruction to halt mode
• Illegal address reset
• Internal steering diode and pullup resistor on RESET pin to VDD
• Internal RESET pin pulldown from COP watchdog and ILADR

Mask Options
The MC68HC05K3 contains these eight mask options:
1. COP watchdog timer (enable or disable)
2. IRQ triggering (edge-sensitive or edge- and level-sensitive)
3. Port A interrupts (enable or disable)
4. Port software programmable pulldowns (enable or disable)
5. STOP instruction (enable or disable)
6. Oscillator type (crystal/ceramic resonator or RC)
7. RC oscillator type (2-pin or 3-pin)
8. RC oscillator startup delay (4064 or 16 f cycles)

 The MC68HC05K3 has a 1024-byte memory map. Therefore, it uses only the lower 10 bits of the address bus. In the following discussion, the upper six bits of the address bus can be ignored. Also, by using a mask option, the STOP instruction can be converted from acting as the normal
STOP instruction.
 The stack area also is reduced to 32 bytes due to the limited amount of RAM. Therefore, the stack pointer is reduced to only five bits, only decrements down to $00E0, and then wraps around to $00FF. All other instructions and registers behave as described in M6805 HMOS/M146805 CMOS Family User’s Manual,Motorola document order number M6805UM/AD3.

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