MPC5200B Users Guide, Rev. 1
11-18 Freescale Semiconductor
ATA Register Interface
Bits Name Description
0:7 Data Register contains the command code sent to the drive. When this register is written,
command execution begins immediately. Writing this register clears any pending interrupt
condition.
8—Reserved
9 HUT Host UDMA burst Terminate—Software can terminate UDMA burst prematurely by setting
this bit. Bits 15 through 10 are unaffected and retain previous values.
10 FR FIFO Reset—Hardware resets FIFO when the direction is switched from Tx to Rx. No
hardware reset is done for Rx to Tx switch. Software must verify FIFO is empty before filling
it for Tx. When bit 10 is set, FIFO is being reset and bits 15, 14, 13, 12, 11, 9 and 8 are
invalid.
11 FE Enable FIFO flush in Rx mode—For all commands except DEVICE RESET, this register is
written only when the ATA dr ive status register bits BSY and DRQ equal 0 and DMACK is not
asserted. If this register is written when BSY or DRQ bits are set to 1, the result is
indeterminate except for the DEVICE RESET command.
Register content is not valid when drive is in sleep mode.
12 IE Enables drive interrupt to pa ss to CPU in DMA/UDMA modes. Software writes to this register
as follows:
FE (bit 11) and IE ( bit 12)
Clear IE and set FE if SDMA task loop count is the same as the data transfer requested
from the drive.
The following is a typical sequence if the BestComm task loop is a larger count than data
request programmed for the drive:
1. Start transaction with IE set and FE cleared.
2. Repeat 1 until task loop count expires.
3. Start last transaction with IE clear and FE set.
Controller issues flush at end.
Task loop completes and interrupts CPU.
CPU responds to SDMA interrupt instead of drive interrupt.
UDMA (bit 13)—Set when UDMA protocol is selected for data transfer, cleared for DMA
protocol.
READ (bit 14)—Set when read command for DMA /UDMA protocols is written to drive
command register, cleared otherwise.
WRITE (bit 15)—Set when write command for DMA /UDMA protocols is written to drive
command register, cleared otherwise.
MANDATORY—Be Aware: Dr ive interrupt must be enabled by clearing bit 1 of drive control
register for DMA/UDMA mode transfers.
13 U DAMA Bit is set when UDMA protocol is selected, cleared when multiword DMA protocol is selected.
14 READ Bit is set when READ DMA command is issued.
15 WRITE Bit is set when WRITE DMA command is issued.
16:31 — Reserved