Table of Contents
Advertisement
GDMA CONTROLLER
9.4 GDMA MODE OPERATION
9.4.1 SOFTWARE MODE
It is the mode that GDMA operates without specific request signal with just setting the enable bit of control
register by software. When we want to enable the operation, the data transmission is started by setting [3:1] of
GDMA mode selection bit of DCON register to "000" and [0] bit of the same register to "1". This mode can
transmit data between the memories by sending the data, which is designated by the source address register to
the destination address register. The data transmission size can be byte, half-word, or word. It is determined by
setting [7:6] bit of DCON register.
9.4.2 EXTERNAL GDMA REQUEST MODE
GDMA of S3C2501X has four external GDMA request (xGDMA_Req) sources. xGDMA_Req signal and
xGDMA_Ack signal can be shared with port signals. So it is used by setting I/O Ports register (IOPCON1).
(Refer to Chapter 12, I/O Ports). External device sending xGDMA_Req transmits the data by GDMA during
receiving xGDMA_Ack signal. Also external GDMA request mode is used by setting GDMA mode selection bit
[3:1] of DCON register to "001". It is similar to the basic operation mode of software, but it is different that GDMA
transmits the data only after receiving xGDMA_Req signal. The first external GDMA request xGDMA_Req0 can
be serviced by GDMA channel 0 and 4. The second external GDMA request xGDMA_Req1 can be serviced by
GDMA channel 1 and 5. The third external GDMA request xGDMA_Req2 can be serviced by GDMA channel 2.
The fourth external GDMA request xGDMA_Req3 can be serviced by GDMA channel 3. If the slow external
devices need the GDMA service, the slow external devices can sample the external GDMA ACK signal by setting
DCON [16:13] bits. DCON [16:13] bits provide the range of 1 and 16 cycles of the external GDMA ACK signal.
The block mode can be used only with the external GDMA request mode.
9.4.3 HUART MODE
S3C2501X has one HUART. GDMA channel 3,4,5 can transmit the data of HUART. If GDMA mode selection bit
[3:1] to "010" or "011", GDMA gets ready to communicate with HUART. If GDMA mode is "010" (HUART TX
mode) and GDMA receives the request signal transmitted from HUART, GDMA transfers Tx data of HUART in
memory into Tx buffer/FIFO of HUART. If GDMA mode is "011" (HUART RX mode) and GDMA receives the
request signal transmitted from HUART, GDMA transfers Rx data of Rx buffer/FIFO of HUART into memory.
When GDMA transmits the data of HUART, GDMA operates in the unit of byte. If it is requested by HUART, only
one byte is transmitted and GDMA waits the following request. (At this time if GDMA transfer count register is
zero, the operation ends.)
In HUART mode, you should set byte ("00") on transfer size (TS) [7:6] of DCON register. In HUART TX
mode, you don't need to care the destination address direction (DD) [11:10] of DCON register either the
DDAR register. In HUART RX mode, you don't need to care the source address direction (SD) [9:8] of
DCON register either the DSAR register.
9-16
NOTE
NOTE
S3C2501X
Advertisement
Table of Contents
