EVB-B1+ WIZnet, EVB-B1+ Datasheet - Page 53

• Manufacturer Part Number: EVB-B1+
• Description: Development Boards & Kits - ARM W3150A+EVAL BOARD BASED ON AVR
• Manufacturer: WIZnet

Specifications of EVB-B1+

• Rohs: yes
• Product: Evaluation Boards
• Interface Type: RS-232, SPI
• Operating Supply Voltage: 3.3 V, 5 V
• Data Bus Width: 8 bit
• Dimensions: 50 mm x 40 mm
• Processor Series: ATmega128

Let’s take a brief look at Ping message before we proceed to Ping program.
Ping message has the value of ‘0’(Ping Reply) or ‘8’(Ping Request) at Type Field. The Code Field of ICMP
Message has 0. Type Dependant Data Field(4Bytes) of ICMP Message can be re-defined as ID
Field(2Bytes), Sequence Number Field(2Bytes) respectively. Data Field of ICMP Message is filled with the
Ping data to be looped back.
Finally, it calculates the checksum of ICMP header and Ping data of which the checksum fields are 0. After
the calculation, it replaces 0 checksum fields with the newly calculated values.
<Fig 3.10> is a diagramming representation of the relationship between the ICMP message format and the
Ping message.
<Fig 3.10: ICMP Message VS Ping Message>
Checking the Ping reply to the Ping request can be processed by checking if the values of ID, sequence
number and ping data field are same or not. In case the Ping reply does not come back in wait time, the ping
can be sent again. In such case, the Ping request is sent with the sequence number incremented by 1.
Transmitting Ping request message and checking the Ping reply message were done by ping(). The
elements of ping() are of destination IP address, Ping reply wait time, number of Ping requests. Ping data
size and received Ping Replies are analyzed and processed to fit the elements.
<Fig 3.11> is the process of ping() and Ping message is defined and used as the data type of <Table 3-21>.
Refer to “inet/ping.h”
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