MC9S08LC36LH Freescale Semiconductor, MC9S08LC36LH Datasheet - Page 65

• Manufacturer Part Number: MC9S08LC36LH
• Description: IC MCU 36K FLASH 2K RAM 64-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HCS08r

Specifications of MC9S08LC36LH

• Core Processor: HCS08
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Size: 36KB (36K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.5K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 2x12b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 64-LQFP
• Processor Series: S08LC
• Core: HCS08
• Data Bus Width: 8 bit
• Data Ram Size: 2.5 KB
• Interface Type: I2C/SCI/SPI1/SPI2
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 18
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWS08
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 2-ch x 12-bit
• For Use With: DEMO9S08LC60 - BOARD DEMO FOR 9S08LC60
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Even if the application will use the reset default settings of COPE, COPCLKS and COPT, the user must
write to the write-once SOPT1 and SOPT2 registers during reset initialization to lock in the settings. That
way, they cannot be changed accidentally if the application program gets lost. The initial writes to SOPT1
and SOPT2 will reset the COP counter.
The write to SRS that services (clears) the COP counter must not be placed in an interrupt service routine
(ISR) because the ISR could continue to be executed periodically even if the main application program
fails.
When the bus clock source is selected, the COP counter does not increment while the MCU is in
background debug mode or while the system is in stop mode. The COP counter resumes once the MCU
exits background debug mode.
When the 1-kHz clock source is selected, the COP counter is re-initialized to zero upon entry to either
background debug mode or stop mode. The COP counter begins from zero once the MCU exits
background debug mode or stop mode.
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 set to 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 follows 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.
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
Interrupts
MC9S08LC60 Series Data Sheet: Technical Data, Rev. 4
Chapter 5 Resets, Interrupts, and System Configuration
65