LAN91C111 Datasheet, PDF (45/125 Pages) SMSC Corporation – 10/100 Non-PCI Ethernet Single Chip MAC + PHY

LAN91C111
8.8 Bank 0 - Counter Register
OFFSET
6
NAME
COUNTER REGISTER
TYPE
READ ONLY
SYMBOL
ECR
Counts four parameters for MAC statistics. When any counter reaches 15 an interrupt is issued. All counters are cleared
when reading the register and do not wrap around beyond 15.
HIGH
BYTE
LOW
BYTE
NUMBER OF EXC. DEFFERED TX
0
0
0
0
MULTIPLE COLLISION COUNT
0
0
0
0
NUMBER OF DEFFERED TX
0
0
0
0
SINGLE COLLISION COUNT
0
0
0
0
Each four bit counter is incremented every time the corresponding event, as defined in the EPH STATUS REGISTER
bit description, occurs. Note that the counters can only increment once per enqueued transmit packet, never faster, lim-
iting the rate of interrupts that can be generated by the counters. For example if a packet is successfully transmitted
after one collision the SINGLE COLLISION COUNT field is incremented by one. If a packet experiences between 2 to
16 collisions, the MULTIPLE COLLISION COUNT field is incremented by one. If a packet experiences deferral the
NUMBER OF DEFERRED TX field is incremented by one, even if the packet experienced multiple deferrals during its
collision retries.
The COUNTER REGISTER facilitates maintaining statistics in the AUTO RELEASE mode where no transmit interrupts
are generated on successful transmissions.
Reading the register in the transmit service routine will be enough to maintain statistics.
8.9 Bank 0 - Memory Information Register
OFFSET
NAME
MEMORY INFORMATION
8
REGISTER
TYPE
READ ONLY
SYMBOL
MIR
HIGH
BYTE
FREE MEMORY AVAILABLE (IN BYTES * 2K * M)
0
0
0
0
0
1
0
0
LOW
BYTE
MEMORY SIZE (IN BYTES *2K * M)
0
0
0
0
0
1
0
0
FREE MEMORY AVAILABLE - This register can be read at any time to determine the amount of free memory. The reg-
ister defaults to the MEMORY SIZE upon POR (Power On Reset) or upon the RESET MMU command.
MEMORY SIZE - This register can be read to determine the total memory size.
All memory related information is represented in 2K * M byte units, where the multiplier M is 1 for LAN91C111.
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DS00002276A-page 45