
DMA Registers
5-84
ADSP-BF59x Blackfin Processor Hardware Reference
Handshake MDMA Initial Block Count Registers
(HMDMAx_BCINIT)
The
HMDMAx_BCINIT
register, shown in
Figure 5-19
, holds the number of
transfers to do per edge of the
DMARx
control signal.
Handshake MDMA Current Block Count Registers
(HMDMAx_BCOUNT)
The
HMDMAx_BCOUNT
register, shown in
Figure 5-20
, holds the number of
transfers remaining for the current edge. MDMA requests are generated if
this count is greater than 0.
Examples:
• 0000 = 0 transfers remaining
• FFFF = 65535 transfers remaining
The
BCOUNT
field is loaded with
BCINIT
when
ECOUNT
is greater than 0 and
BCOUNT
is expired (0). Also, if the
RBC
bit in the
HMDMAx_CONTROL
register is
written to 1,
BCOUNT
is loaded with
BCINIT
. The
BCOUNT
field is decre-
mented with each MDMA grant. It is cleared when
HMDMA
is disabled.
A
block done
interrupt is generated when
BCOUNT
decrements to 0. If the
MBDI
bit in the
HMDMAx_CONTROL
register is set, the interrupt is suppressed
until
ECOUNT
is 0. If
BCINIT
is 0, no
block done
interrupt is generated,
since no DMA requests were generated or grants received.
Figure 5-19. Handshake MDMA Initial Block Count Registers
0
0
0
0
0
0
15 14
13 12 11 10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
Handshake MDMA Initial Block Count Registers (HMDMAx_BCINIT)
BCINIT[15:0] (Initial Block
Count)
Reset = 0x0000
Содержание ADSP-BF59x Blackfin
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