National Instruments AT-DIO-32F, User Manual

Page: 59 / 155

Programming Chapter 4
AT-DIO-32F User Manual 4-12 © National Instruments Corporation
Bit Name Description (continued)
12 TRANS32 32-Bit Transfer Enable.
When TRANS32 is set, the AT-DIO-32F is in 32-bit transfer
mode. This mode uses the Group 1 handshaking lines (REQ1 and
ACK1). When REQ1 is received, DRDY1 and DRDY2 are both
set. When data is read or written for both Group 1 and Group 2,
the ACK1 line is asserted. Two read or write operations are
required for each 32-bit transfer. If TRANS32 is cleared, the AT-
DIO-32F is in regular 16-bit mode.
11 WRITEC Port C Write/Read Bit.
When WRITEC is set, Port C is configured for a write operation.
When WRITEC is cleared, Port C is configured for a read
operation. If Port C is configured for a write operation, after every
LRESET2 this bit must first be cleared and then set again for
reinitializing handshaking purposes (or clear and set DIOCEN of
the CFG2 Register).
10 WRITEA Port A Write/Read Bit.
When WRITEA is set, Port A is configured for a write operation.
When WRITEA is cleared, Port A is configured for a read
operation. If Port A is configured for a write operation, after every
LRESET1 this bit must first be cleared and then set again for
reinitializing handshaking purposes (or clear and set DIOAEN of
the CFG1 Register).
9 CNT2SRC Counter 2 Source Select Bit.
The CNT2SRC bit selects the counting source for Counter 2. If
CNT2SRC is set, the output of Counter 3 is used as the counting
source for Counter 2. If CNT2SRC is cleared, a 10-MHz clock is
used as the counting source for Counter 2.
8 CNT1SRC Counter 1 Source Select Bit.
The CNT1SRC bit selects the counting source for Counter 1. If
CNT1SRC is set, the output of Counter 3 is used as the counting
source for Counter 1. If CNT1SRC is cleared, a 10-MHz clock is
used as the counting source for Counter 1.
7 DBLDMA Double DMA Mode Enable Bit.
When DBLDMA is set, the AT-DIO-32F is in double DMA
channel mode. In double DMA mode, only the Group 1
handshaking lines are used. DMA transfers use the DMA channel
selected for Group 1 until a DMA terminal count is received; then
the DMA channel selected for Group 2 is used for the Group 1
DMA transfers until a DMA terminal count for that channel is
received. DMA transfers switch between the two channels. This
configuration transfers data on one DMA channel and services data
on another channel at the same time.