Оценок - 2, средний балл: 4
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Фрагмент инструкции
5-68 C141-E050-02EN 5.3 Host Commands Table 5.13 Command code and parameters (2 of 2) Command name Error register (X’1F1’) Status register (X’1F7’) BBK UNC INDF ABRT TK0NF DRDY DWF ERR WRITE VERIFY V V V V V V V READ VERIFY SECTOR(S) V V V V V V V RECALIBRATE V V V V V SEEK V V V V V INITIALIZE DEVICE PARAMETERS V V V V IDENTIFY DEVICE V V V V IDENTIFY DEVICE DMA V V V V SET FEATURES V V V V SET MULTIPLE MODE V V V V EXECUTE DEVICE DIAGNOSTIC * * * * * V READ LONG V V V V V V WRITE LONG V V V V V V READ BUFFER V V V V WRITE BUFFER V V V V IDLE V V V V IDLE IMMEDIATE V V V V STANDBY V V V V STANDBY IMMEDIATE V V V V SLEEP V V V V CHECK POWER MODE V V V V SMART V V V V V SECURITY DISABLE PASSWORD V V V V SECURITY ERASE PREPARE V V V V SECURITY ERASE UNIT V V V V SECURITY FREEZE LOCK V V V V SECURITY SET PASSWORD V V V V FLUSH CACHE V V V V V Invalid command V V V V V: Valid on this command *: See the command descriptioms. C141-E050-02EN 5-69 Interface 5.4 Command Protocol The host should confirm that the BSY bit of the Status register of the device is 0 prior to issue a command. If BSY bit is 1, the host should wait for issuing a command until BSY bit is cleared to 0. Commands can be executed only when the DRDY bit of the Status register is 1. However, the following commands can be executed even if DRDY bit is 0. • EXECUTE DEVICE DIAGNOSTIC • INITIALIZE DEVICE PARAMETERS 5.4.1 Data transferring commands from device to host The execution of the following commands involves data transfer from the device to the host. • IDENTIFY DEVICE. • IDENTIFY DEVICE DMA • READ SECTOR(S) • READ LONG • READ BUFFER • SMART The execution of these commands includes the transfer one or more sectors of data from the device to the host. In the READ LONG command, 516 bytes are transferred. Following shows the protocol outline. a) The host writes any required parameters to the Features, Sector Count, Sector Number, Cylinder, and Device/Head registers. b) The host writes a command code to the Command register. c) The device sets the BSY bit of the Status register and prepares for data transfer. d) When one sector of data is available for transfer to the host, the device sets DRQ bit and clears BSY bit. The drive then asserts INTRQ signal. e) After detecting the INTRQ signal assertion, the host reads the Status register. The host reads one sector of data via the Data register. In response to the Status register being read, the device negates the INTRQ signal. f) The drive clears DRQ bit to 0. If transfer of another sector is requested, the device sets the BSY bit and steps d) and after are repeated. Even if an error is encountered, the device prepares for data transfer by setting the DRQ bit. Whether or not to transfer the data is determined for each host. In other 5-70 C141-E050-02EN 5.4 Command Protocol C141-E050-02EN 5-71 words, the host should receive the relevant sector of data (512 bytes of uninsured dummy data) or release the DRQ status by resetting. Figure 5.3 shows an example of READ SECTOR(S) command protocol, and Figure 5.4 shows an example protocol for command abort. Figure 5.3 Read Sector(s) command protocol Note: For transfer of a sector of data, the host needs to read Status register (X’1F7’) in order to clear INTRQ (interrupt) signal. The Status register should be read within a period from the DRQ setting by the device to 50 ms after the completion of the sector data transfer. Note that the host does not need to read the Status register for the reading of a single sector or the last Interface sector in multiple-sector reading. If the timing to read the Status register does not meet above condition, normal data transfer operation is not guaranteed. When the host new command even if the device requests the data transfer (setting in DRQ bit), the correct device operation is not guaranteed. Figure 5.4 Protocol for command abort 5.4.2 Data transferring commands from host to device The execution of the following commands involves Data transfer from the host to the drive. • WRITE SECTOR(S) • WRITE LONG • WRITE BUFFER • WRITE VERIFY • SECURITY DISABLE PASSWORD • SECURITY ERASE UNIT • SECURITY SET PASSWORD • SECURITY UNCLOK The execution of these commands includes the transfer one or more sectors of data from the host to the device. In the WRITE LONG command, 516 bytes are transferred. Following shows the protocol outline. a) The host writes any required parameters to the Features, Sector Count, Sector Number, Cylinder, and Device/Head registers. 5-72 C141-E050-02EN 5.4 Command Protocol b) The host writes a command code in the Command register. The drive sets the BSY bit of the Status register. c) When the device is ready to receive the data of the first sector, the device sets DRQ bit and clears BSY bit. d) The host writes one sector of data through the Data register. e) The device clears the DRQ bit and sets the BSY bit. f) When the drive completes transferring the data of the sector, the device clears BSY bit and asserts INTRQ ...
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