IA186EM_04 Datasheet, PDF (13/133 Pages) InnovASIC, Inc – 8/16-Bit Microcontrollers

IA186EM/IA188EM
8/16-BIT Microcontrollers
Data Sheet
As of Production Version -03
SDEC (bit 11) – Source Decrement, when set to 1, automatically decrements the destination address
after each transfer. The address is decremented by 1 or 2, depending on the byte/word bit (Bn/W, bit
0). The address does not change if the increment and decrement bits are set to the same value (00b or
11b).
SINC (bit 10) – Source Increment, when set to 1, automatically increments the destination address
after each transfer. The address is incremented by 1 or 2, depending on the byte/word bit (Bn/W, bit
0). The address does not change if the increment and decrement bits are set to the same value (00b or
11b).
TC (bit 9) – Terminal Count. The DMA decrements the transfer count for each DMA transfer. When
TC is set to 1, the source or destination synchronized DMA transfers terminate when the count reaches
0, but when TC is set to 0, source or destination synchronized DMA transfers do not terminate when
the count reaches 0. Unsynchronized DMA transfers always end when the count reaches 0,
irrespective of the setting of this bit.
INT (bit 8) – Interrupt. The DMA channel generates an interrupt request on completion of the transfer
count when this bit is set to 1. However, for an interrupt to be generated, the TC bit must also be set
to 1.
SYN1-SYN0 (bits 7-6) – Synchronization Type bits select channel synchronization as shown in the
following table. The value of these bits is ignored if TDRQ (bit 4) is set to 1. A processor reset
causes these bits to be set to 11b.
SYN1
0
0
1
1
SYN0
0
1
0
1
Sync Type
Unsynchronized
Source Synchronized
Destination Synchronized
Reserved
P (bit 5) – Relative Priority. Selects high priority for this channel relative to the other channel during
simultaneous transfers when set to 1.
TDRQ (bit 4) - Timer 2 Synchronization. Enables DMA requests from timer 2, when set to 1, but
disables DMA requests from timer 2 when set to 0.
EXT (bit 3) – Reserved.
CHG (bit 2) – Change Start Bit. This bit must be set to 1, to allow modification of the ST bit during a
write. During a write, when CHG is set to 0, ST is not changed when writing the control word. The
result of reading this bit is always 0.
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