mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 153

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

5.7.3.3 16-Bit Expanded Mode
MC68HC16Y3/916Y3
USER’S MANUAL
Data bus mode select current is specified in APPENDIX A ELECTRICAL CHARAC-
TERISTICS. Do not confuse pin function with pin electrical state. Refer to 5.7.5 Pin
State During Reset for more information.
16-bit data bus operation is selected when BERR = 1 and DATA1 = 0 during reset. In
this configuration, pins ADDR[18:3] and DATA[15:0] are configured as address and
data pins, respectively. The alternate functions for these pins as ports A, B, G, and H
are unavailable. ADDR[23:20] can be configured as chip selects or address bus pins.
ADDR[2:0] are configured as address bus pins.
DATA2 determines the functions of BR/CS0, FC0/CS3, and FC2/CS5. DATA[7:3]
determine the functions of ADDR[23:19]/CS[10:6]. A data bus pin pulled low selects
the associated chip select and all lower-numbered chip-selects down through CS6.
For example, if DATA5 is pulled low during reset, CS[8:6] are configured as address
bus signals ADDR[21:19], and CS[10:9] are configured as chip selects. On
MC68HC16Y3/916Y3 MCUs, ADDR[23:20] follow the state of ADDR19, and DA-
TA[7:4] have limited use. Refer to 5.9.4 Chip-Select Reset Operation for more infor-
mation.
DATA8 determines the function of the DSACK[1:0], DS, AS, and SIZ[1:0] pins. If
DATA8 is held low during reset, these pins are used for discrete I/O (port E).
DATA9 determines the function of interrupt request pins (IRQ[7:0]) and the clock mode
select pin (MODCLK). When DATA9 is held low during reset, these pins are used for
discrete I/O (port F).
DATA11 determines whether the SCIM2 operates in test mode out of reset. This
capability is used for factory testing of the MCU.
Figure 5-18 Alternate Circuit for Data Bus Mode Select Conditioning
DATA PIN
RESET
1N4148
Freescale Semiconductor, Inc.
1 k
For More Information On This Product,
Go to: www.freescale.com
DATA PIN
RESET
2 k
1 k
2N3906
ALTERNATE DATA BUS CONDITION CIRCUIT
MOTOROLA
5-45