Since SATA is applied to ATAPI devices, transmission performance is not the most important consideration. Software and hardware compatibility is the most important issue, so it is not easy to master in design. This article will give a brief introduction to the IC design of SATA supporting ATAPI components. I hope that readers can have a clearer understanding of the design points that should be considered for the application of SATA to ATAPI components.
SATA supports ATAPI design points
On the SATA related hard disk and the SATA controller on the motherboard, the so-called SATA IC design mode can be divided into two types: NaTIve Design and Bridge Design:
? Native design: The so-called native design refers to the conversion of the SATA signal to other interfaces without the conversion of the bridge interface. For example: PCI to SATA control card, the so-called native design, refers to the direct conversion of the PCI signal to the SATA signal, without any interface transfer.
Bridge design: The so-called bridge design refers to the conversion of the existing interface on the market to the SATA interface through the conversion of the bridge interface. For example, there is a PCI to ATA interface on the market. By adding an ATA to SATA interface, it can be integrated into a PCI to SATA control interface. This design pattern is also the fastest way for vendors to introduce SATA products.
At present, most of the SATA hard disks on the market adopt the bridge design mode, that is, on the original hard disk control chip, and then an external PATA (Parallel ATA) to SATA Bridge Chip. You can become a hard drive that supports SATA. As for optical storage devices (such as DVD+RW, CD-RW, etc.), it is also the easiest to introduce SATA soluTIon in bridge design. However, ATAPI devices (such as DVD+RW, CD-RW, etc.) have many limitations in the design of SATA, especially compatibility issues. If you use PATA to SATA bridge chip plus optical storage existing control chip, you can provide SATA DVD+RW, CD-RW solution, but PATA to SATA bridge chip in the design of ATAPI support, but fully reflected in SATA Compatibility of optical storage devices. The following are the things to consider when using SATA for ATAPI Device design.
In general, the problems that SATA applies to ATAPI Device design can be divided into the following categories:
1. Protocol Issue
This type of problem usually occurs when there are partial differences between the existing PATA specifications and the latest SATA specifications. Several common situations include the following examples:
? PIO DR0 data block problem over 8K
This issue is not related to the original ATAPI specification (see Table 2). SATA Spec. defines DATA FIS not to exceed 8K size, but optical storage media according to ATAPI specifications, there are often many CD-R, CD-RW, DVD+RW PIO DR0 data block exceeds 8K size limit, at this time PATA To SATA bridge must consider this kind of SATA and ATAPI transmission protocol different places, properly handled, the system can operate normally.
Odd word problem
As far as the definition of SATA is concerned, SATA transmission is based on DW (double word) transmission, but some ATAPI OP code is based on odd word transmission (please refer to Table 3), so SATA bridge is necessary to understand transfer count. Related information to resolve these issues. If not handled properly, the system will transfer the excess word data to the memory or optical storage media on the host side, causing a system error.
In the past, the habit of optical storage media, some optical drive operations will send INTRQ to prepare to receive the command packet. However, in the SATA communication protocol, the SATA host does not send INTRQ, which will cause the system to crash, because the software must receive the INTRQ to start the operation of sending the command packet. Therefore, the design of the PATA to SATA bridge must compensate for the lack of specifications.
? Transfer count problem
Due to the wide variety of CD-R or DVD blank formats, it will be difficult for the SATA bridge to understand the full transfer count of the disc, and the SATA bridge will not know when the data will end. This often requires a very robust method to deal with the transfer count problem, SATA bridge must also be able to compensate for the problem of protocol imperfections.
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