AM79C978VCSLASHW datasheet(145/261 Pages) AMD

145 / 261 page

Am79C978

145

Bus Configuration Registers (BCRs)

The BCRs are used to program the configuration of the

bus interface and other special features of the

Am79C978 controller that are not related to the IEEE

802.3 MAC functions. The BCRs are accessed by first

setting the appropriate RAP value and then by perform-

ing a slave access to the BDP. See Table 35.

All BCR registers are 16 bits in width in Word I/O mode

(DWIO = 0, BCR18, bit 7) and 32 bits in width in DWord

I/O mode (DWIO = 1). The upper 16 bits of all BCR reg-

isters is undefined when in DWord I/O mode. These

bits should be written as zeros and should be treated

as undefined when read. The default value given for

any BCR is the value in the register after H_RESET.

Some of these values may be changed shortly after

H_RESET when the contents of the external EEPROM

is automatically read in. None of the BCR register val-

ues are affected by the assertion of the STOP bit or

S_RESET.

Note that several registers have no default value.

BCR0, BCR1, BCR3, BCR8, BCR10-17, and BCR21

are reserved and have undefined values. BCR2 and

BCR34 are not observable without first being pro-

grammed through the EEPROM read operation or a

user register write operation.

BCR0, BCR1, BCR16, BCR17, and BCR21 are regis-

ters that are used by other devices in the PCnet family.

Writing to these registers have no effect on the opera-

tion of the Am79C978 controller.

Writes to those registers marked as “Reserved” will

have no effect. Reads from these locations will produce

undefined values.

BCR0: Master Mode Read Active

Bit

Name

Description

31-16 RES

Reserved locations. Written as

zeros and read as undefined.

15-0

MSRDA

Reserved

locations.

After

H_RESET, the value in this regis-

ter will be 0005h. The setting of

this register has no effect on any

Am79C978 controller function. It

is only included for software com-

patibility with other PCnet family

devices.

Read always. MSRDA is read

only. Write operations have no ef-

fect.

BCR1: Master Mode Write Active

Bit

Name

Description

31-16 RES

Reserved locations. Written as

zeros and read as undefined.

15-0

MSWRA

Reserved

locations.

After

H_RESET, the value in this regis-

ter will be 0005h. The setting of

this register has no effect on any

Am79C978 controller function. It

is only included for software com-

patibility with other PCnet family

devices.

Read always. MSWRA is read

only. Write operations have no ef-

fect.

BCR2: Miscellaneous Configuration

Note: Bits 15-0 in this register are programmable

through the EEPROM.

Bit

Name

Description

31-16 RES

Reserved locations. Written as

zeros and read as undefined.

15-14 RES

Reserved locations. Written and

read as zeros.

PHYSELEN This

bit

enables

writes

BCR18[4:3] for software selec-

tion of various operation and test

modes. When PHYSELEN is set

to 0 (default), the two bits can

only be written from the EE-

PROM. When PHYSELEN is set

to 1, writes to BCR18[4:3] are en-

abled.

This bit is always read/write ac-

cessible. TSTSHDEN is cleared

to 0 by H_RESET and is unaffect-

ed by S_RESET or by setting the

STOP bit.

LEDPE

LED

Program

Enable.

When

LEDPE is set to 1, programming

the

LED0

(BCR4),

LED1

(BCR5), LED2 (BCR6), LED3

(BCR7), and LED4 (BCR48) reg-

isters is enabled. When LEDPE is

cleared to 0, programming of

LED0 (BCR4), LED1 (BCR5),

LED2 (BCR6), LED3 (BCR7),

and LED4 (BCR48) registers is

disabled. Writes to those regis-

ters will be ignored.

AM79C978VC/W 数据表(PDF) 145 Page - Advanced Micro Devices

AM79C978VC/W 数据表(HTML) 145 Page - Advanced Micro Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载

链接网址

AM79C978VC/W 数据表(PDF) 145 Page - Advanced Micro Devices

AM79C978VC/W 数据表(HTML) 145 Page - Advanced Micro Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表 下载

链接网址

数据表下载