MC68HC705B16CFN

Manufacturer Part NumberMC68HC705B16CFN
DescriptionIC MCU 2.1MHZ 15K OTP 52-PLCC
ManufacturerFreescale Semiconductor
SeriesHC05
MC68HC705B16CFN datasheet
 


Specifications of MC68HC705B16CFN

Core ProcessorHC05Core Size8-Bit
Speed2.1MHzConnectivitySCI
PeripheralsPOR, WDTNumber Of I /o32
Program Memory Size15KB (15K x 8)Program Memory TypeOTP
Eeprom Size256 x 8Ram Size352 x 8
Voltage - Supply (vcc/vdd)4.5 V ~ 5.5 VData ConvertersA/D 8x8b
Oscillator TypeInternalOperating Temperature-40°C ~ 85°C
Package / Case52-PLCCLead Free Status / RoHS StatusContains lead / RoHS non-compliant
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9.2
Interrupts
The MCU can be interrupted by four different sources: three maskable hardware interrupts and
one non maskable software interrupt:
External signal on the IRQ pin
Serial communications interface (SCI)
Programmable timer
Software interrupt instruction (SWI)
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:
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.
9
9.2.1
Interrupt priorities
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
shows the relative priority of all the possible interrupt sources.
the interrupt processing flow.
9.2.2
Nonmaskable software interrupt (SWI)
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
RESETS AND INTERRUPTS
Figure 9-3
shows
MC68HC05B6
Rev. 4.1