Sundance-spas ST201 Uživatelský manuál stáhnout pdf (Strana 117)

117

Sundance Technology ST201 PRELIMINARY draft 2

MAXLAT

Class....................PCI Configuration Registers, Configuration

Base Address ......PCI device configuration header start

Address Offset.....0x3f

Access Mode.......Read Only

Width ...................8 bits

BIT BIT NAME BIT DESCRIPTION

7..0 MaxLat MaxLat specifies, in 250 ns increments, how often the ST201 requires

bus access while operating as a bus master. The value for MaxLat is

stored in the ConfigParm word in EEPROM. Assumes the PCI system

allows 64-byte maximum bursts with full duplex operation, the ST201-

based 100 Mbps systems return the value 10 in this field, implying a

latency tolerance of 2.5us, according to the calculation:

64 bytes/(12.5 MB/s x 2) = 2.56us

The result is rounded to 2.5 us, which is 250 ns * 10

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Sundance-spas ST201 Uživatelský manuál Strana 117