SCSI Registers
4-77
Register: 0x47
General Purpose Pin Control (GPCNTL)
Read/Write
This register is used to determine if the pins controlled by the
register are inputs or outputs. Bits [4:0] in GPCNTL
correspond to bits [4:0] in the GPREG register. When the bits are
enabled as inputs, an internal pull-up is also enabled.
ME
Master Enable
7
When the ME bit is set, the bus master state of the
device is presented on GPIO1. GPIO1 goes low when the
part is a bus master. When set, the ME bit is independent
of the setting of bit 1 (GPIO1). If the GPIO1 is configured
as an input while the ME bit is set, the Master bit will still
toggle the GPIO1 pin.
FE
Fetch Enable
6
If the FE bit is set, GPIO0 reflects when an internal
opcode fetch is being performed. GPIO0 goes low when
an opcode fetch is performed. When set, the FE bit is
independent of the setting of bit 0 (GPIO0). If GPIO0 is
configured as an input, the Fetch bit still toggles GPIO0.
LEDC
LED_CNTL
5
If the LED_CNTL bit is set GPIO0 reflects the state of the
SCSI bus, connected (GIO0 is low) or not connected
(GPIO0 is high). This occurs if bit 6 (FE) is not set and
the chip is not currently performing an EEPROM
autodownload. This bit provides a hardware solution for
driving an external SCSI activity LED.
GPIO[4:2]
GPIO Enable
[4:2]
The general purpose control corresponds to bits [4:2] in
the
register and to the
GPIO4–GPIO2 pins. GPIO4 powers-up as a general
purpose output. GPIO[3:2] power-up as general purpose
inputs.
7
6
5
4
2
1
0
ME
FE
LEDC
GPIO[4:2]
GPIO[1:0]
0
0
x
0
1
1
1
1
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
Страница 314: ...6 40 Specifications This page intentionally left blank...
Страница 318: ...6 44 Specifications This page intentionally left blank...
Страница 344: ...6 70 Specifications This page intentionally left blank...
Страница 350: ...6 76 Specifications Figure 6 42 LSI53C1000 329 Ball Grid Array Bottom view...
Страница 352: ...6 78 Specifications...
Страница 360: ...A 8 Register Summary...
Страница 376: ...IX 12 Index...