SI3482-A01-GM Silicon Laboratories Inc, SI3482-A01-GM Datasheet - Page 10

• Manufacturer Part Number: SI3482-A01-GM
• Description: IC CTLR POE 24-48PORT PSE 24-QFN
• Manufacturer: Silicon Laboratories Inc

Specifications of SI3482-A01-GM

• Applications: Power Over Ethernet Controller
• Current - Supply: 12.1mA
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-WFQFN Exposed Pad
• Product: Power Distribution
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Si3482
3.1. Packet Format
A packet is a sequence of fields sent together as a unit. Figure 7 shows the SPP packet format.
Each field is a single byte except for the Data field. The Data field may be from zero to 255 bytes.
3.1.1. Start Field
The Start field marks the beginning of a packet and always contains the Start-of-Packet (SOP) character (0xAC). If
data is lost on the host interface, the Serial Packet Server and the Serial Packet Client use the Start field to
resynchronize. A “receive packet” routine starts by receiving and discarding bytes until the SOP character is found.
3.1.2. Checksum Field
The Checksum field is used to verify that the packet was not corrupted during transmission. The sender of a packet
calculates the checksum and writes it into the Checksum field. The receiver of a packet verifies that the checksum
is correct. The Checksum field should contain the value such that all the bytes in the packet, except for the Start
field, add up to zero.
To calculate the checksum, the sender uses an 8-bit variable to sum up the bytes of the Routine field through the
end of the Data field. The sender adds one to the one's complement of this sum and stores the result in the
Checksum field.
To verify the checksum, the receiver uses an 8-bit variable to sum up the bytes of the Routine field through the
Checksum field. The sum should be zero.
3.1.3. Routine Field
The Routine field identifies a routine in the Power Manager API.
The client uses the Routine field to specify which routine to call. The client should verify that the Routine field in a
received packet matches the Routine field in the sent packet.
10
GetTotalPowerConsumed()
GetTotalPowerProvided()
GetTotalPowerGranted()
GetSystemStatus()
GetSystemInfo()
GetPortStatus()
GetPortCount()
GetPortInfo()
Routine
Start Routine Data Length Data Checksum
Start Routine Data Length Data Checksum
Figure 8. Packet Checksum
Figure 7. Packet Format
Table 6. Routine Field
Checksum
Sum of Bytes is Zero
RTN_GETTOTALPOWERCONSUMED
RTN_GETTOTALPOWERPROVIDED
Rev. 0.1
RTN_GETTOTALPOWERGRANTED
=
RTN_GETSYSTEMSTATUS
RTN_GETSYSTEMINFO
RTN_GETPORTSTATUS

RTN_GETPORTCOUNT
RTN_GETPORTINFO
~Sum

Symbol
+
1
Value
1
2
3
4
5
6
7
8