DA82562EM Intel, DA82562EM Datasheet - Page 113

• Manufacturer Part Number: DA82562EM
• Manufacturer: Intel

Specifications of DA82562EM

• Lead Free Status / Rohs Status: Not Compliant

6.5.3.2
6.5.3.3
Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual
Table 51. CU Control Commands: Actions at Acceptance Time
Table 52. CU Activities Performed at the End of Execution
CU Resume Command
The CU Resume (CU_RESUME) command resumes CU operation. The 8255x completes the
following sequence:
CU Control Commands Response
The start and resume CU control (CUC) commands can be issued through the SCB CUC command
field. The command block offset pointer in the general pointer register of the SCB points to the first
executable action command. These action commands have a field for the end of list (EL) and
suspend (S) bits. The EL bit indicates that the current action command is the last on the command
list. The presence of the S bit indicates that the user wants the CU to enter the suspended state after
executing the current command.
The mechanism used to suspend the CU is the S bit in the action command block. Suspending the
CU through the action command block results in suspension after a specific command is executed.
The CU can be re-activated by issuing a resume command.
Idle
Suspended
Active
1. If the CU is in the suspended state it goes to the active state and requests the beginning of the
2. If the CU is in the active state, it verifies the validity of the S bits in the current and next action
3. If the CU is in the idle state, it ignores the CU_RESUME command.
Present State
EL Bit
next CB. Since the 8255x remembers the pointer to the next action command, it does not re-
read the link pointer in the previous CB. However, the 8255x re-reads the S bit in the previous
CB to determine if the driver has modified it while the device was suspended. If the S bit is
cleared, it proceeds to execute the new CB. If the S bit is still set in the previous CB, the CU
goes back to the suspended state.
commands. If the S bit is cleared in the current CB, it proceeds to the next CB in the list after
execution of the current CB is completed.
0
0
1
1
S Bit
0
1
0
1
Next State
Active
Active
Prohibited
Active
Suspended
Idle
Idle
Next State
Table 51
CU Start
Action
Start processing CB
pointed to by SCB
general pointer.
Start processing CB
pointed to by SCB
general pointer.
Not applicable.
Start processing CB
CNA interrupt
CNA/CI interrupt
CNA/CI interrupt
Action
and
Table 52
illustrate the various state transitions.
Next State
Idle
Active
Active
Host Software Interface
CU Resume
Action
None.
Start processing next CB
if S bit is clear on current
CB.
Re-check S bit on current
CB. If not set, process
next CB.
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