Dma State Machine; Software Requirements - Freescale Semiconductor MPC5200B User Manual

ATA Host Controller Operation
Counter
t93
tA
tB N/A (Timing controlled by drive controller)
tC N/A (Timing controlled by drive controller)
Note:
1. Since t1 and t1
to count both, by loading in an initial value that depends on the PIO mode being used. This is the responsibility of
software.
2. Since t3 (WDATA setup time) is a minimum, and t3 <= t2 for all PIO modes, t2 is used to determine when to drive
Write_Data on DD.
3. Since t4 and t9 are both minimum specs, and t4 >= t9 for all PIO modes, t4 is used to count from DIOR/DIOW negate
to CS[1]FX/CS[3]FX/ADDR negate.
If ATA drive address space is accessed by CPU, the ATA IPBI module generates:
• a signal to enable the PIO mode state machine
• a wait state to the IPBI module to hold off any further IPBI module access
The PIO state machine indicates transfer is in progress to the IPBI module. This extends the transfer wait to the IPBI module until the PIO
transaction is complete.
11.4.2

DMA State Machine

The interface between the ATA Controller DMA channel and the rest of the system is through a standard Type 1 BestComm FIFO interface.
Table 11-32 shows the timing requirements specified in the ATA-4 spec for multiword DMA data transfers.
Counter
TM START (Negate CS0, CS1,
set DMA_In_Progress flag)
TE N/A (Timing controlled
by drive controller)
TD
TK
TH
T0
TJ
TN
11.4.2.1

Software Requirements

Software calculates the appropriate values of TD and TK based on information reported for the cycle time (T0) in the drive's IDENTIFY
DEVICE data and the operating clock frequency. Cycle time (T0) must be greater than the sum of TD and TK.
11-22
Table 11-31. PIO Timing Requirements (continued)
Start from
N/A (Use t4 instead)
t1
are both minimum specs, and t1 <= t1 for PIO modes 0–2, and t1 >= t1 for PIO modes 3–4, t1 is used
Table 11-32. Multiword DMA Timing Requirements
Start from
TM
Latch Read Data/Drive Write Data
TD
TD
TD
T0
T0
MPC5200B Users Guide, Rev. 1
Activity at end
—
Check IORDY
—
—
Activity at end
Assert DMACK,
Assert DIOR/DIOW,
Write Data ready
—
Negate DIOR/DIOW,
Assert DIOR/DIOW
Ready for new write data
Begin next cycle
Start TJ, Start TN
Negate DMACK,
Go to Idle
Clear DMA_In_Progress flag.
Allow CS0, CS1 to be driven
Dependencies
—
IORDY=1
—
—
Dependencies
DMARQ asserted by drive
—
DMARQ=1
DMARQ=1
DMARQ=1
DMARQ=1
DMARQ=0
DMARQ Negated,
DMACK asserted, T0=0
DMARQ Negated,
DMACK asserted, T0=0
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