MC68376BGMAB20 Freescale Semiconductor, MC68376BGMAB20 Datasheet - Page 134

• 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: -

5-56
MOTOROLA
Chip-select assertion can be synchronized with bus control signals to provide output
enable, read/write strobe, or interrupt acknowledge signals. Chip-select logic can also
generate DSACK and AVEC signals internally. A single DSACK generator is shared
by all chip-selects. Each signal can also be synchronized with the ECLK signal avail-
able on ADDR23.
When a memory access occurs, chip-select logic compares address space type, ad-
dress, type of access, transfer size, and interrupt priority (in the case of interrupt ac-
knowledge) to parameters stored in chip-select registers. If all parameters match, the
appropriate chip-select signal is asserted. Select signals are active low.
If a chip-select function is given the same address as a microcontroller module or an
internal memory array, an access to that address goes to the module or array, and the
chip-select signal is not asserted. The external address and data buses do not reflect
the internal access.
All chip-select circuits are configured for operation out of reset. However, all chip-se-
lect signals except CSBOOT are disabled, and cannot be asserted until the BYTE[1:0]
field in the corresponding option register is programmed to a non-zero value to select
a transfer size. The chip-select option register must not be written until a base address
has been written to a proper base address register. Alternate functions for chip-select
pins are enabled if appropriate data bus pins are held low at the release of RESET.
Refer to 5.7.3.1 Data Bus Mode Selection for more information. Figure 5-20 is a
functional diagram of a single chip-select circuit.
DSACK
BUS CONTROL
AVEC
ADDRESS
INTERNAL
SIGNALS
Figure 5-20 Chip-Select Circuit Block Diagram
GENERATOR
AVEC
BASE ADDRESS REGISTER
ADDRESS COMPARATOR
SYSTEM INTEGRATION MODULE
OPTION COMPARE
OPTION REGISTER
GENERATOR
DSACK
ASSIGNMENT
REGISTER
PIN
CONTROL
TIMING
AND
REGISTER
DATA
PIN
USER’S MANUAL
PIN
MC68336/376
CHIP SEL BLOCK