MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 249

• Manufacturer Part Number: MCF51EM256CLL
• Description: IC MCU 32BIT 256KB FLASH 100LQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF51EMr

Specifications of MCF51EM256CLL

• Core Processor: Coldfire V1
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 16x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: MCF51EM
• Core: ColdFire V1
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: RS-232, LIN
• Maximum Clock Frequency: 50 MHz
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: DEMOEM
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

10.3.6
The eight read-only interrupt acknowledge (IACK) registers can be explicitly addressed by the
memory-mapped accesses or implicitly addressed by a processor-generated interrupt acknowledge cycle
during exception processing when CPUCR[IAE] is set. In either case, the interrupt controller's actions are
similar.
First, consider an IACK cycle to a specific level, a level-n IACK. When this type of IACK arrives in the
interrupt controller, the controller examines all currently-active level-n interrupt requests, determines the
highest priority within the level, and then responds with the unique vector number corresponding to that
specific interrupt source. The vector number is supplied as the data for the byte-sized IACK read cycle.
If there is no active interrupt source at the time of the level-n IACK, a special spurious interrupt vector
(vector number 24 (0x18)) is returned. It is the responsibility of the service routine to manage this error
situation.
This protocol implies the interrupting peripheral is not accessed during the acknowledge cycle because the
interrupt controller completely services the acknowledge. This means the interrupt source must be
explicitly disabled in the peripheral device by the interrupt service routine. This approach provides unique
vector capability for all interrupt requests, regardless of the complexity of the peripheral device.
Second, the interrupt controller also supports the concept of a software IACK. This is the ability to query
the interrupt controller near the end of an interrupt service routine (after the current interrupt request has
been negated) to determine if there are any pending (but currently masked) interrupt requests. If the
response to the software IACK's byte operand read is non-zero, the service routine uses the returned value
as the vector number of the highest pending interrupt request and passes control to the appropriate new
handler. If the returned value is zero, there is no pending interrupt request.
This process avoids the overhead of a context restore and RTE instruction execution, followed
immediately by another interrupt exception and context save. In system environments with high rates of
interrupt activity, this mechanism can noticeably improve overall performance. For additional details on
software IACKs, see
Freescale Semiconductor
LVLnIACK Reset
SWIACK Reset
Offset: CF1_INTC_BASE + 0x20 (INTC_SWIACK)
Table 10-9. Software and Level-n IACK Registers (INTC_SWIACK, INTC_LVLnIACK)
INTC Software and Level-n IACK Registers (n = 1,2,3,...,7)
W
R
CF1_INTC_BASE + 0x20 + (4×n) (INTC_LVLnIACK)
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
7
0
0
0
Section 10.6.3, “More on Software IACKs.”
0
0
6
0
0
5
0
1
4
VECN
0
1
3
2
0
0
Interrupt Controller (CF1_INTC)
0
0
1
Access: Read-only
0
0
0
10-13