XC68HC705B32CB Freescale Semiconductor, XC68HC705B32CB Datasheet - Page 110

• Manufacturer Part Number: XC68HC705B32CB
• Description: IC MCU 2.1MHZ 32K OTP 56-DIP
• Manufacturer: Freescale Semiconductor
• Series: HC05r

Specifications of XC68HC705B32CB

• Core Processor: HC05
• Core Size: 8-Bit
• Speed: 2.1MHz
• Connectivity: SCI
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: OTP
• Eeprom Size: 256 x 8
• Ram Size: 528 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 56-SDIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

9
9.2
The MCU can be interrupted by four different sources: three maskable hardware interrupts and
one non maskable software interrupt:
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•
•
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Interrupts cause the processor to save the register contents on the stack and to set the interrupt
mask (I-bit) to prevent additional interrupts. The RTI instruction (ReTurn from Interrupt) causes the
register contents to be recovered from the stack and normal processing to resume. While
executing the RTI instruction, the value of the I-bit is replaced by the corresponding I-bit stored on
the stack.
Unlike reset, hardware interrupts do not cause the current instruction execution to be halted, but
are considered pending until the current instruction is complete. The current instruction is the one
already fetched and being operated on. When the current instruction is complete, the processor
checks all pending hardware interrupts. If interrupts are not masked (I-bit clear) and the
corresponding interrupt enable bit is set, the processor proceeds with interrupt processing;
otherwise, the next instruction is fetched and executed.
Note:
9.2.1
Each potential interrupt source is assigned a priority level, which means that if more than one
interrupt is pending at the same time, the processor will service the one with the highest priority
first. For example, if both an external interrupt and a timer interrupt are pending after an instruction
execution, the external interrupt is serviced first.
Table 9-2
the interrupt processing flow.
9.2.2
The software interrupt (SWI) is an executable instruction and a nonmaskable interrupt: it is
executed regardless of the state of the I-bit in the CCR. If the I-bit is zero (interrupts enabled), SWI
is executed after interrupts that were pending when the SWI was fetched, but before interrupts
Freescale
9-6
External signal on the IRQ pin
Serial communications interface (SCI)
Programmable timer
Software interrupt instruction (SWI)
shows the relative priority of all the possible interrupt sources.
Power-on and external reset clear all interrupt enable bits, but set the INTE bit in the
miscellaneous register, thus preventing interrupts during the reset sequence.
Interrupts
Interrupt priorities
Nonmaskable software interrupt (SWI)
RESETS AND INTERRUPTS
Figure 9-3
MC68HC05B6
Rev. 4.1
shows