Freescale Semiconductor MPC5200B - Manual (Page 393)

MPC5200B Users Guide, Rev. 1
11-28 Freescale Semiconductor
ATA Bus Background
11.7.3.1 ATA Register Addressing
The address used to reference an ATA drive register. This is the actual address (CS[1]FX, CS[3]FX, DA[2:0]) present on the physical ATA
interface.
Table 11-37 gives details.
11.7.3.2 Drive Interrupt
A pending drive interrupt is cleared by the following actions:
• Read of status (not the alternate status) register
• Write to command register
11.7.3.3 Sector Addressing
Sector addressing is the address used to reference data on the drive. It is the address used by the low-level drivers to access a particular piece
of data and to place it into one or more ATA registers as part of a command block. To understand the data addressing, it is necessary to
understand the physical organization of data in a drive, as presented in
Figure 11-1 . Each drive contains a number of disks, each with one or
two heads (one head per surface). Each disk is divided into concentric tracks that are then divided into a number of sectors. A sector is the
smallest unit of data that can be written or read by a drive. The collections of tracks that can be accessed by the heads at a single position is
called a cylinder. Therefore, a sector can be uniquely identified by a sector number, a head number and a cylinder number. From this
addressing scheme there are two ways to address an individual sector: physical addressing and logical block addressing, which are described
in the next two sections.
Table 11-37. ATA Register Address/Chip Select Decoding
Address Function
System
Address
CS[1]FX CS[3]FX DA[2] DA[1] DA[0]
READ (DIOR) WRITE (DIOW)
Control Block Registers
— 1 1 x x x Data bus high impedance Not used
03F0–03F3 1 0 0 x x Data bus high impedance Not used
03F4–03F5 1 0 1 0 x Data bus high impedance Not used
03F6 1 0 1 1 0 Alternate status Device control
03F7 1 0 1 1 1 Obsolete Not used
Command Block Registers
01F0 0 1 0 0 0 Data Data
01F1 0 1 0 0 1 Error register Features
01F2 0 1 0 1 0 Sector count Sector count
01F3 0 1 0 1 1 Sector number Sector number
01F3 0 1 0 1 1 LBA bits 0–7 1 LBA bits 0–7 1
01F4 0 1 1 0 0 Cylinder low Cylinder low
01F4 0 1 1 0 0 LBA bits 8–15 1 LBA bits 8–15 1
01F5 0 1 1 0 1 Cylinder high Cylinder high
01F5 0 1 1 0 1 LBA bits 16–23 1 LBA bits 16–23 1
01F6 0 1 1 1 0 Drive/head Drive/head
01F6 0 1 1 1 0 LBA bits 24–27 1 LBA bits 24–27 1
01F7 0 1 1 1 1 Status Command
— 0 0 x x x Invalid address Invalid address
Note:
1. LBA mode register mapping—system addresses are for a single channel, accommodating two drives only.