7.3.3PACKET LAYER DEFINITION Data Packet Structure

Byte

Description

Byte Value range

1

Header

128 to 255

2

Packet Count

0 to 127

3

Serial No. Length S

1 to 127

4

Data block length D

1 to 127

5to(4 + S)

Serial No.

32 to 127

(5 + S)to(4 + S+D)

Data Block

0 to 127

(5 + S + D)

XOR Checksum

0 to 127

(6 + S + D)

Additive Checksum

0 to 127

Minimum packet size is 8 bytes.

Maximum packet size is 260 bytes.

The same packet structure is used for both transmissions from the master (Command Packets) and transmissions from the Controller (Reply Packets). A dialogue is always initiated by a Command Packet from the master.

Header

This byte, which must have bit 7 set (i.e. value between 128 and 255), identifies the purpose of the packet (a full description of all the different types of packet is given later).

Packet Count

This byte may take a value between 0 and 127, and should be incremented by 1for each Command Packet transmitted by the master, except when the packet is a retransmission due to the fact that no reply was received to the last Command Packet (in which case the Packet Count should remain at the value of the original Command Packet).

When the Packet Count reaches 127, the Packet Count of the next Command Packet should be 0. When the Controller replies, the Packet Count byte in the Reply Packet is set to the same value as in the corresponding Command Packet. This allows the master to positively associate Reply Packets with Command Packets.

The Controller doesperform validation of the Packet Count field in some circumstances. For example, when transferring a file from the master to a Controller, the file is split into packets and transmitted one packet at a time. As the Controller receives each packet it acknowledges this to the master. It is possible, however, that the acknowledgement is lost (e.g. due to noise), and the master has no way of knowing whether the Controller ever received that packet or not (as far as the Controller is concerned, the transaction was completed successfully). In this case, after the time-out period has elapsed (see below; Packet Timing) when the master re-transmits the Command Packet, the Packet Count will be the same as in the preceding Command Packet. The Controller, upon receiving this duplicate packet (which it can identify by the Packet Count) simply acknowledges the packet, but does not store the data.

Serial Number Length

In Command Packets this is set to the length (in characters) of the serial number of the Controller to which the packet is intended, hi Reply Packets, this is set to the length (in characters) of the serial number of the Controller which is transmitting the reply.

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Sanyo 550 instruction manual Header, Packet Count, Serial Number Length
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550 specifications

The Sanyo 550 is a remarkable piece of technology, encapsulating innovative features and advanced characteristics that cater to a variety of users. This device, designed with meticulous attention to detail, is particularly renowned for its versatility and user-friendly interface.

One of the standout features of the Sanyo 550 is its impressive display technology. The high-resolution screen offers vibrant colors and sharp images, making it ideal for both professional presentations and personal entertainment. Whether you're watching videos or reviewing documents, the clarity provided by the Sanyo 550's display enhances the overall user experience.

In terms of connectivity, the Sanyo 550 excels with multiple options available, including USB ports, Bluetooth, and Wi-Fi capabilities. These features allow users to seamlessly connect various devices, transfer files effortlessly, and access the internet without hassle. This level of connectivity ensures that the Sanyo 550 can function as a central hub for all your multimedia needs, whether for work or leisure.

The Sanyo 550 also incorporates advanced battery technology. With its long-lasting power supply, users can enjoy extended usage without frequent recharging. This is particularly beneficial for individuals who are constantly on the go, as it allows for uninterrupted productivity and entertainment.

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The device is also equipped with powerful processing capabilities, enabling smooth multitasking and efficient performance. Whether running demanding applications or performing routine tasks, the Sanyo 550 maintains high performance levels, ensuring a satisfying user experience.

Lastly, the Sanyo 550 places emphasis on user satisfaction through its intuitive operating system. The interface is designed to be straightforward and accessible, allowing users of all tech-savvy levels to navigate with ease. Overall, the Sanyo 550 represents a blend of cutting-edge technology, portability, and user-centered design, making it a compelling choice for anyone in the market for a reliable and feature-rich device.
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