mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 400

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

STRB — Address Strobe/Data Strobe
DSACK[3:0] — Data Strobe Acknowledge
SPACE[1:0] — Address Space Select
D-22
MOTOROLA
This bit controls the timing for assertion of a chip-select in asynchronous mode only.
Selecting address strobe causes the chip-select to be asserted synchronized with
address strobe. Selecting data strobe causes the chip-select to be asserted
synchronized with data strobe. Data strobe timing is used to create a write strobe when
needed.
This field specifies the source of DSACK in asynchronous mode as internally
generated or externally supplied. It also allows the user to adjust bus timing with
internal DSACK generation by controlling the number of wait states that are inserted
to optimize bus speed in a particular application. Table D-15 shows the DSACK[3:0]
field encoding.The fast termination encoding (%1110) effectively corresponds to –1
wait states.
Use this option field to select an address space for chip-select assertion or to configure
a chip-select as an interrupt acknowledge strobe for an external device. The CPU16
normally operates in supervisor mode only, but interrupt acknowledge cycles take
place in CPU space.Table D-16 shows address space bit encodings.
0 = Address strobe
1 = Data strobe
DSACK[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Freescale Semiconductor, Inc.
For More Information On This Product,
Table D-15 DSACK Field Encoding
Clock Cycles Required
Go to: www.freescale.com
REGISTER SUMMARY
Per Access
10
11
12
13
14
15
16
—
3
4
5
6
7
8
9
2
Wait States Inserted
–1 (Fast termination)
External DSACK
Per Access
10
11
12
13
0
1
2
3
4
5
6
7
8
9
MC68HC16Y3/916Y3
USER’S MANUAL