Ata Register Addressing; Drive Interrupt; Sector Addressing - Freescale Semiconductor MPC5200B User Manual

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.
System
CS[1]FX
Address
— 1
03F0–03F3 1
03F4–03F5 1
03F6 1
03F7 1
01F0 0
01F1 0
01F2 0
01F3 0
01F3 0
01F4 0
01F4 0
01F5 0
01F5 0
01F6 0
01F6 0
01F7 0
— 0
Note:
1. LBA mode register mapping—system addresses are for a single channel, accommodating two drives only.
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
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.
11-28
Table 11-37. ATA Register Address/Chip Select Decoding
Address
CS[3]FX DA[2] DA[1]
1 x
0 0
0 1
0 1
0 1
1 0
1 0
1 0
1 0
1 0
1 1
1 1
1 1
1 1
1 1
1 1
1 1
0 x
MPC5200B Users Guide, Rev. 1
READ (DIOR)
DA[0]
Control Block Registers
x x Data bus high impedance
x x Data bus high impedance
0 x Data bus high impedance
1 0 Alternate status
1 1 Obsolete
Command Block Registers
0 0 Data
0 1 Error register
1 0 Sector count
1 1 Sector number
1 1 LBA bits
0 0 Cylinder low
0 0 LBA bits
0 1 Cylinder high
0 1 LBA bits
1 0 Drive/head
1 0 LBA bits
1 1 Status
x x Invalid address
Figure 11-1. Each drive contains a number of disks, each with one or
Function
WRITE (DIOW)
Not used
Not used
Not used
Device control
Not used
Data
Features
Sector count
Sector number
0–71 LBA bits 0–71
Cylinder low
8–151 LBA bits 8–151
Cylinder high
16–231 LBA bits 16–231
Drive/head
24–271 LBA bits 24–271
Command
Invalid address
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