4.2.2 Additional Interface Signals

 

 

Table 4.8 describes the Additional Interface Signals group.

Table 4.8

Additional Interface Signals

 

 

 

 

Name

Pin No.

Type

Description

 

 

 

 

TESTIN/

52

I

Test In. When this pin is driven LOW, the LSI53C810A connects all

 

 

 

inputs and outputs to an “AND tree.” The SCSI control signals and data

 

 

 

lines are not connected to the “AND tree.” The output of the “AND tree”

 

 

 

is connected to the Test Out pin. This allows manufacturers to verify

 

 

 

chip connectivity and determine exactly which pins are not properly

 

 

 

attached. When the TESTIN pin is driven LOW, internal pull-ups are

 

 

 

enabled on all input, output, and bidirectional pins, all outputs and

 

 

 

bidirectional signals will be 3-stated, and the MAC/_TESTOUT pin will

 

 

 

be enabled. Connectivity can be tested by driving one of the

 

 

 

LSI53C810A pins LOW. The MAC/_TESTOUT pin should respond by

 

 

 

also driving LOW.

 

 

 

 

GPIO0_

48

I/O

General Purpose I/O pin. Optionally, when driven LOW, this pin

FETCH/

 

 

indicates that the next bus request will be for an opcode fetch. This pin

 

 

 

powers up as a general purpose input.

 

 

 

This pin has two specific purposes in the LSI Logic SDMS software.

 

 

 

SDMS software uses it to toggle SCSI device LEDs, turning on the LED

 

 

 

whenever the LSI53C810A is on the SCSI bus. SDMS software drives

 

 

 

this pin LOW to turn on the LED, or drives it HIGH to turn off the LED.

 

 

 

This signal can also be used as data I/O for serial EEPROM access. In

 

 

 

this case it is used with the GPIO0 pin, which serves as a clock, and

 

 

 

the pin can be controlled from PCI configuration register 0x35 or

 

 

 

observed from the General Purpose (GPREG) operating register, at

 

 

 

address 0x07.

 

 

 

 

GPIO1_

49

I/O

General Purpose I/O pin. Optionally, when driven LOW, indicates that

MASTER/

 

 

the LSI53C810A is bus master. This pin powers up as a general

 

 

 

purpose input.

 

 

 

LSI Logic SDMS software supports use of this signal in serial EEPROM

 

 

 

applications, when enabled, in combination with the GPIO0 pin. When

 

 

 

this signal is used as a clock for serial EEPROM access, the GPIO1 pin

 

 

 

serves as data, and the pin is controlled from PCI configuration register

 

 

 

0x35.

 

 

 

 

4-10

Signal Descriptions

Page 72
Image 72
LSI 53C810A technical manual Additional Interface Signals