MC68HC711E20CFN2 Freescale Semiconductor, MC68HC711E20CFN2 Datasheet - Page 122

• Manufacturer Part Number: MC68HC711E20CFN2
• Description: IC MCU 20K 2MHZ OTP 52-PLCC
• Manufacturer: Freescale Semiconductor
• Series: HC11r

Specifications of MC68HC711E20CFN2

• Core Processor: HC11
• Core Size: 8-Bit
• Speed: 2MHz
• Connectivity: SCI, SPI
• Peripherals: POR, WDT
• Number Of I /o: 38
• Program Memory Size: 20KB (20K x 8)
• Program Memory Type: OTP
• Eeprom Size: 512 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 52-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Resets and Interrupts
5.6.1 Interrupt Recognition and Register Stacking
Technical Data
122
For some interrupt sources, such as the SCI interrupts, the flags are
automatically cleared during the normal course of responding to the
interrupt requests. For example, the RDRF flag in the SCI system is
cleared by the automatic clearing mechanism consisting of a read of the
SCI status register while RDRF is set, followed by a read of the SCI data
register. The normal response to an RDRF interrupt request would be to
read the SCI status register to check for receive errors, then to read the
received data from the SCI data register. These steps satisfy the
automatic clearing mechanism without requiring special instructions.
An interrupt can be recognized at any time after it is enabled by its local
mask, if any, and by the global mask bit in the CCR. Once an interrupt
source is recognized, the CPU responds at the completion of the
instruction being executed. Interrupt latency varies according to the
number of cycles required to complete the current instruction. When the
CPU begins to service an interrupt, the contents of the CPU registers are
pushed onto the stack in the order shown in
value is stacked, the I bit and the X bit, if XIRQ is pending, are set to
inhibit further interrupts. The interrupt vector for the highest priority
pending source is fetched and execution continues at the address
specified by the vector. At the end of the interrupt service routine, the
return-from-interrupt instruction is executed and the saved registers are
pulled from the stack in reverse order so that normal program execution
can resume. Refer to
Table 5-5. Stacking Order on Entry to Interrupts
Memory Location
Resets and Interrupts
SP–1
SP–2
SP–3
SP–4
SP–5
SP–6
SP–7
SP–8
SP
Section 3. Central Processor Unit
CPU Registers
Table
M68HC11E Family — Rev. 3.2
ACCA
ACCB
CCR
PCH
PCL
IYH
IXH
IYL
IXL
5-5. After the CCR
(CPU).
MOTOROLA