MC9S08JM32CLD Freescale Semiconductor, MC9S08JM32CLD Datasheet - Page 67

• Manufacturer Part Number: MC9S08JM32CLD
• Description: IC MCU 8BIT 32K FLASH 44-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HCS08r

Specifications of MC9S08JM32CLD

• Core Processor: HCS08
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, LIN, SCI, SPI, USB
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-LQFP
• Processor Series: S08JM
• Core: HCS08
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: SCI/SPI
• Maximum Clock Frequency: 24 MHz
• Number Of Programmable I/os: 33
• Number Of Timers: 8
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWS08
• Development Tools By Supplier: DEMOJM, DEMOJMSKT, DEMOFLEXISJMSD, DEMO9S08JM16
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 12-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

5.5
Interrupts provide a way to save the current CPU status and registers, execute an interrupt service routine
(ISR), and then restore the CPU status so processing resumes where it left off before the interrupt. Other
than the software interrupt (SWI), which is a program instruction, interrupts are caused by hardware events
such as an edge on the IRQ pin or a timer-overflow event. The debug module can also generate an SWI
under certain circumstances.
If an event occurs in an enabled interrupt source, an associated read-only status flag will become set. The
CPU will not respond until and unless the local interrupt enable is a logic 1 to enable the interrupt. The
I bit in the CCR is 0 to allow interrupts. The global interrupt mask (I bit) in the CCR is initially set after
reset which masks (prevents) all maskable interrupt sources. The user program initializes the stack pointer
and performs other system setup before clearing the I bit to allow the CPU to respond to interrupts.
When the CPU receives a qualified interrupt request, it completes the current instruction before responding
to the interrupt. The interrupt sequence obeys the same cycle-by-cycle sequence as the SWI instruction
and consists of:
While the CPU is responding to the interrupt, the I bit is automatically set to avoid the possibility of
another interrupt interrupting the ISR itself (this is called nesting of interrupts). Normally, the I bit is
restored to 0 when the CCR is restored from the value stacked on entry to the ISR. In rare cases, the I bit
may be cleared inside an ISR (after clearing the status flag that generated the interrupt) so that other
interrupts can be serviced without waiting for the first service routine to finish. This practice is not
recommended for anyone other than the most experienced programmers because it can lead to subtle
program errors that are difficult to debug.
The interrupt service routine ends with a return-from-interrupt (RTI) instruction which restores the CCR,
A, X, and PC registers to their pre-interrupt values by reading the previously saved information off the
stack.
When two or more interrupts are pending when the I bit is cleared, the highest priority source is serviced
first (see
Freescale Semiconductor
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Saving the CPU registers on the stack
Setting the I bit in the CCR to mask further interrupts
Fetching the interrupt vector for the highest-priority interrupt that is currently pending
Filling the instruction queue with the first three bytes of program information starting from the
address fetched from the interrupt vector locations
Table
Interrupts
For compatibility with the M68HC08, the H register is not automatically
saved and restored. It is good programming practice to push H onto the stack
at the start of the interrupt service routine (ISR) and restore it immediately
before the RTI that is used to return from the ISR.
5-1).
MC9S08JM60 Series Data Sheet, Rev. 3
NOTE
Chapter 5 Resets, Interrupts, and System Configuration
67