MC68376BGMAB20 Freescale Semiconductor, MC68376BGMAB20 Datasheet - Page 139

• Manufacturer Part Number: MC68376BGMAB20
• Description: IC MCU 32BIT 8K ROM 160-QFP
• Manufacturer: Freescale Semiconductor
• Series: M683xxr

Specifications of MC68376BGMAB20

• Core Processor: CPU32
• Core Size: 32-Bit
• Speed: 20MHz
• Connectivity: CAN, EBI/EMI, SCI, SPI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Type: ROMless
• Ram Size: 7.5K x 8
• Voltage - Supply (vcc/vdd): 4.75 V ~ 5.25 V
• Data Converters: A/D 16x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 160-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

5.9.3 Using Chip-Select Signals for Interrupt Acknowledge
MC68336/376
USER’S MANUAL
When a match occurs, the chip-select signal is asserted. Assertion occurs at the same
time as AS or DS assertion in asynchronous mode. Assertion is synchronized with
ECLK in synchronous mode. In asynchronous mode, the value of the DSACK field de-
termines whether DSACK is generated internally. DSACK[3:0] also determines the
number of wait states inserted before internal DSACK assertion.
The speed of an external device determines whether internal wait states are needed.
Normally, wait states are inserted into the bus cycle during S3 until a peripheral as-
serts DSACK. If a peripheral does not generate DSACK, internal DSACK generation
must be selected and a predetermined number of wait states can be programmed into
the chip-select option register. Refer to the SIM Reference Manual (SIMRM/AD) for
further information.
Ordinary bus cycles use supervisor or user space access, but interrupt acknowledge
bus cycles use CPU space access. Refer to 5.6.4 CPU Space Cycles and 5.8 Inter-
rupts for more information. There are no differences in flow for chip-selects in each
type of space, but base and option registers must be properly programmed for each
type of external bus cycle.
During a CPU space cycle, bits [15:3] of the appropriate base register must be config-
ured to match ADDR[23:11], as the address is compared to an address generated by
the CPU.
Figure 5-21 shows CPU space encoding for an interrupt acknowledge cycle. FC[2:0]
are set to %111, designating CPU space access. ADDR[3:1] indicate interrupt priority,
and the space type field (ADDR[19:16]) is set to %1111, the interrupt acknowledge
code. The rest of the address lines are set to one.
Figure 5-21 CPU Space Encoding for Interrupt Acknowledge
ACKNOWLEDGE
INTERRUPT
FUNCTION
1 1 1
2
CODE
0
SYSTEM INTEGRATION MODULE
23
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
CPU SPACE
TYPE FIELD
19
16
ADDRESS BUS
LEVEL
0
1
MOTOROLA
CPU SPACE IACK TIM
5-61