GR712RC-UM, Jun 2017, Version 2.9 120 www.cobham.com/gaisler
GR712RC
16.7 AMBA interface
The AMBA interface consists of an APB interface, an AHB master interface and DMA FIFOs. The
APB interface provides access to the user registers. The DMA engines have 32-bit wide FIFOs to the
AHB master interface which are used when reading and writing to the bus.
The transmitter DMA engine reads data from the bus in bursts which are half the FIFO size in length.
A burst is always started when the FIFO is half-empty or if it can hold the last data for the packet. The
burst containing the last data might have shorter length if the packet is not an even number of bursts in
size.
011011Write, incre-
menting
address, do
not verify
before writ-
ing, send
acknowledge
Executed normally. No restric-
tions. If AHB error occurs error
code is set to 1. Reply is sent.
011100Write, single
address, ver-
ify before
writing, no
acknowledge
Executed normally. Length must
be 4 or less. Otherwise nothing is
done. Same alignment restric-
tions apply as for rmw. No reply
is sent.
011101Write, incre-
menting
address, ver-
ify before
writing, no
acknowledge
Executed normally. Length must
be 4 or less. Otherwise nothing is
done. Same alignment restric-
tions apply as for rmw. If they
are violated nothing is done. No
reply is sent.
011110Write, single
address, ver-
ify before
writing, send
acknowledge
Executed normally. Length must
be 4 or less. Otherwise nothing is
done and error code is set to 9.
Same alignment restrictions
apply as for rmw. If they are vio-
lated nothing is done and error
code is set to 10. If an AHB error
occurs error code is set to 1.
Reply is sent.
011111Write, incre-
menting
address, ver-
ify before
writing, send
acknowledge
Executed normally. Length must
be 4 or less. Otherwise nothing is
done and error code is set to 9.
Same alignment restrictions
apply as for rmw. If they are vio-
lated nothing is done and error
code is set to 10. If an AHB error
occurs error code is set to 1.
Reply is sent.
1 0 - - - - Unused Stored to DMA-channel.
1 1 - - - - Unused Stored to DMA-channel.
Table 91. GRSPW hardware RMAP handling of different packet type and command fields.
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Command Action
Reserved
Command
/ Response
Write /
Read
Ver i fy
data
before
write
Acknow-
ledge
Increment
Address
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