4-86
Registers
FE
Fetch Enable
6
The internal opcode fetch signal is presented on GPIO0
if this bit is set, regardless of the state of bit 0 (GPIO0).
LEDC
LED_CNTL
5
The internal connected signal (bit 3 of the
register) will be presented on GPIO0 if this
bit is set and bit 6 of GPCNTL is cleared and the chip is
not in progress of performing an EEPROM autodownload
regardless of the state of bit 0 (GPIO0). This provides a
hardware solution to driving a SCSI activity LED in many
implementations of LSI Logic SCSI chips.
GPIO
GPIO Enable
[4:2]
General purpose control, corresponding to bit 4 in the
register and the GPIO4 pin.
GPIO4 powers up as a general purpose output, and
GPIO[3:2] power-up as general purpose inputs.
GPIO
GPIO Enable
[1:0]
These bits power-up set, causing the GPIO1 and GPIO0
pins to become inputs. Clearing these bits causes
GPIO[1:0] to become outputs.
Register: 0x48
SCSI Timer Zero (STIME0)
Read/Write
HTH[3:0]
Handshake-to-Handshake Timer Period
[7:4]
These bits select the handshake-to-handshake time-out
period, the maximum time between SCSI handshakes
(SREQ/ to SREQ/ in target mode, or SACK/ to SACK/ in
the initiator mode). When this timing is exceeded, an
interrupt is generated and the HTH bit in the
register is set. The following
table contains time-out periods for the Handshake-to-
Handshake Timer, the Selection/Reselection Timer
(bits [3:0]), and the General Purpose Timer (
bits [3:0]). For a more detailed explanation
of interrupts, refer to
Chapter 2, “Functional Description.”
7
4
3
0
HTH[3:0]
SEL[3:0]
0
0
0
0
0
0
0
0
*
Содержание LSI53C896
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 88: ...2 62 Functional Description...
Страница 112: ...3 24 Signal Descriptions...
Страница 306: ...6 38 Specifications This page intentionally left blank...
Страница 310: ...6 42 Specifications This page intentionally left blank...
Страница 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Страница 340: ...6 72 Specifications...
Страница 346: ...A 6 Register Summary...
Страница 362: ...IX 12 Index...