
SMSC DS – LPC47M14X
Page 163
Rev. 03/19/2001
Table 67 – DMA Channel Select Configuration Register Description
NAME
REG INDEX
0x74 (R/W)
DEFINITION
STATE
C
DMA Channel
Select
Default=0x02 or
0x04
(Note 1)
on VCC POR,
VTR POR,
HARD RESET
and
SOFT RESET
Bits[2:0] select the DMA Channel.
0x00= Reserved
0x01= DMA1
0x02= DMA2
0x03= DMA3
0x04-0x07= No DMA active
Note:
A DMA channel is activated by setting the DMA Channel Select register to [0x01-0x03] AND :
For the FDC logical device by setting DMAEN, bit D3 of the Digital Output Register.
For the PP logical device in ECP mode by setting dmaEn, bit D3 of the ecr.
The DMA channel must be disabled if not used/selected by any Logical Device. Refer to Note A.
Note 1:
The default value of the DMA Channel Select register for logical device 0 (FDD) is 0x02 and for logical
device 3 and 5 is 0x04.
Note A. Logical Device IRQ and DMA Operation
1)
IRQ and DMA Enable and Disable: Any time the IRQ or DMA channel for a logical block is disabled by a
register bit in that logical block, the IRQ and/or DMA channel must be disabled. This is in addition to the IRQ
and DMA channel disabled by the Configuration Registers (active bit or address not valid).
a)
FDC: For the following cases, the IRQ and DMA channel used by the FDC are disabled. Will not
respond to the DMA request.
Digital Output Register (Base+2) bit D3 (DMAEN) set to "0".
The FDC is in power down (disabled).
b)
Serial Ports:
Modem Control Register (MCR) Bit D2 (OUT2) - When OUT2 is a logic "0", the serial port interrupt
is disabled.
c)
Parallel Port:
SPP and EPP modes: Control Port (Base+2) bit D4 (IRQE) set to "0", IRQ is disabled.
ECP Mode:
(1)
(DMA) dmaEn from ecr register. See table.
(2)
IRQ - See table.
MODE
(FROM ECR REGISTER)
CONTROLLED BY
000
PRINTER
001
SPP
010
FIFO
011
ECP
100
EPP
101
RES
110
TEST
111
CONFIG
d)
Keyboard Controller: Refer to the KBD section of this spec.
Note:
IRQ PIN
PDREQ PIN
CONTROLLED BY
IRQE
IRQE
(on)
(on)
IRQE
IRQE
(on)
IRQE
dmaEn
dmaEn
dmaEn
dmaEn
dmaEn
dmaEn
dmaEn
dmaEn