RC82562EP Intel, RC82562EP Datasheet - Page 114

• Manufacturer Part Number: RC82562EP
• Description: IC ETH 10/100 PLC DEV CTRL 64BGA
• Manufacturer: Intel

Specifications of RC82562EP

• Rohs Status: RoHS non-compliant
• Controller Type: Ethernet Controller
• Interface: IEEE 802.3
• Voltage - Supply: 3.135 V ~ 3.465 V
• Mounting Type: Surface Mount
• Package / Case: 64-BGA
• Current - Supply: -
• Operating Temperature: -
• Other names: 832361

Host Software Interface
6.5.4
106
Table 53. RU Control Commands: Actions at Acceptance Time
Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual
Receive Unit Control
The receive unit (RU) is the logical unit that receives frames and stores them in memory. It uses
free buffers and descriptors prepared by the CPU. This section describes how the CPU controls
frame reception (starts, stops, suspends, and resumes the RU). Reception can also be halted due to
a no resource condition.
The RU is modeled as a logical machine that takes one of the following states at any given time.
Software can determine the current RU status by reading the SCB status word in the CSR (bits 5:2).
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•
•
•
Idle (0000). The RU has no memory resources and is discarding incoming frames. This is the
initial RU state after reset.
No Resources Due to No More RFDs (0010). The RU has no memory resources due to a
lack of RFDs and is discarding incoming frames. This state differs from the idle state in that
the RU accumulates statistics on the number of frames it has to discard. The 8255x enters this
state after it processes an RFD that its EL bit set.
Suspended (0001). The RU discards all incoming frames even though free memory resources
exist to store incoming frames. The 8255x enters this state after it processes an RFD with its S
bit set.
Ready (0100). The RU has free memory resources and is ready to store incoming frames.
Idle
No
Resources
due to no
RFDs
Suspended
Ready
Idle
No
Resources
due to No
RFDs
Suspended
Ready
Present
State
Ready
Ready
Ready
Prohibited
Idle
No
Resource
due to No
RFDs
Suspend
Prohibited
State
Next
RU Start
Set Up
RFD
Set Up
RFD
Set Up
RFD
N/A
Request
Start
Request
Start
Request
Start
N/A
Action
Idle
Prohibited
Ready
Prohibited
Idle
Prohibited
Suspend
Prohibited
State
Next
RU Resume
None
N/A
Set Up
RFD
N/A
None
N/A
Request
Resume
N/A
Action
Idle
Idle
Idle
Idle
Idle
Idle
Idle
Idle
State
Next
RU Abort
None
None
None
Start
Discard -
RNR
Interrupt
None
None
None
Abort
DMA -
Start
Discard -
RNR
Interrupt
Action