Datasheet

Internal Registers

SGLS139B − October 2003 − Revised April 2004 TSB12LV32-EP

2.2.7 Maint_Control Register at 1Ch

0 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 29 30 3128

PING VALUE

E_HCRC

E_DCRC

NO_PKT

F_ACK

NO_ACK

ACK

This register is used to generate test conditions. The control bits in this register allow errors to be inserted into

various places in the packets generated by this node. After the completion of error insertion, enabled

error-insertion controls are disabled. The power-up reset value of this register equals 0000 0000h.

BIT

NUMBER

BIT NAME FUNCTION DIR DESCRIPTION

0 E_HCRC Header CRC

error

R/W If E_HCRC is set, the packet header CRC component of the next primary packet generated

by this node is in error or is invalid; otherwise, this bit has no effect. After the next packet for

this node is generated, this bit is cleared.

1 E_DCRC Data CRC

error

R/W If E_DCRC is set, the packet data CRC component of the next primary packet generated by

this node is in error or is be invalid; otherwise, this bit has no effect. After the next packet for

this node is generated, this bit is cleared to zero immediately upon transmission of the erro-

neous CRC.

2 NO_PKT No packet R/W If NO_PKT is set, the next primary packet to be generated by this node is discarded. This bit

is cleared to zero immediately after the next packet for this node is discarded.

3 F_ACK Ack field R/W If F_ACK is set, the ack field is used within the next acknowledge packet generated by this

node. This bit is cleared to zero immediately after the next acknowledge packet for this node

is generated.

4 NO_ACK No ack R/W If NO_ACK is set, the next acknowledge packet (that would normally have been generated

by this node) is not sent. This bit is cleared to zero immediately when the next acknowledge

packet for this node is discarded.

5−7 RESERVED Reserved

8−15 ACK Ack packet

field

R/W The 8-bit ACK field contains the 8-bit acknowledge packet (ack_code and ack_parity) to be

supplied when the F_ACK bit indicates a modified acknowledge packet is to be generated.

16−23 RESERVED Reserved

24−31 PING VALUE Ping timer

value

R/W Ping timer value. This value reflects the time it takes a node to respond to a ping packet.

The granularity of this timer is 40 ns.