ISD-T360 ETC [List of Unclassifed Manufacturers], ISD-T360 Datasheet - Page 48

• Manufacturer Part Number: ISD-T360
• Description: VoiceDSP Digital Speech Processor with Master/Slave, Full-Duplex Speakerphone, Multiple Flash and ARAM/DRAM Support
• Manufacturer: ETC [List of Unclassifed Manufacturers]

2.2.2
DEVICE NUMBER AND TYPE
The VoiceDSP processor supports various types
of Flash memory and ARAM/DRAM devices. Up
to four devices may be connected to the
VoiceDSP, where all the connected devices
must be of the same type. Each memory device
may be of 4Mbit, 8Mbit or 16Mbit; thus a total of
64Mbit non-volatile memory may be connected
for message storage (up to 4 hours of voice re-
cording).
See “MEMORY INTERFACE” on page 1-6, for de-
tailed description of the supported Flash and
ARAM/DRAM devices and the hardware con-
nectivity.
Use the CFG command to define the type and
number of installed memory devices (see “CFG
Configure VoiceDSP config_value” on page 2-
25).
MEMORY DEVICE SIZE
The memory manager handles the memory de-
vices in basic units of 4Kbyts blocks. This ap-
proach is defined due to the nature of Flash
devices where the basic unit that can be erased
is a 4Kbytes block. This constraint is not relevant
for ARAM/DRAM devices, but the concept is
maintained for simplicity and consistency.
Memory blocks cannot be shared by different
voice messages. Therefore, the maximum num-
ber of messages per memory device, equals to
the number of memory blocks minus one (one
block per device is used for memory manage-
ment).
The size of the connected memory devices, is
defined by the number of memory blocks in
each device. Refer to tunable parameter index
62, in Table 2-10, for detailed description of the
available number of blocks for Flash and ARAM/
DRAM devices.
2-8
MEMORY INTERFACE
PRODUCTION LINE TESTING
In many cases it is desired to test the ISD-T360SB
in the production line as part of the whole appli-
cation. Usually in these cases, the testing time is
an important factor and should be minimized as
possible. The initialization time of the memory de-
vices is significant and should be avoided during
production (Refer to Table 1-4). Therefore, a
dedicated parameter is defined in order to allow
a production line testing while using a small part
of the real connected memory size.
It should be noted that in case of power failure
during the production line testing, the connect-
ed memory devices should be replaced, and
the process should be repeated. Refer to pa-
rameter index 63, in Table 2-10, for further expla-
nation of the production line testing.
ARAM QUALITY
ARAM is an Audio Grade RAM device, which im-
plies that some percentage of the ARAM bits are
defected and their content is undefined. Unlike
Flash devices, where the defected bits can be
mapped out, in case of ARAM specific bits can-
not be mapped out; only memory blocks can be
mapped out.
Therefore, it should be noted that using ARAM as
a voice storage device, will result in audible dis-
tortions. It is the user responsibility to define the
maximum allowed bad nibbles (4 bits) in a mem-
ory block. If the number of bad nibbles exceeds
the defined limitation, the specific block is
mapped out and is not used for message re-
cording. Refer to tunable parameter index 64, in
Table 2-10, for further details of the ARAM quality
level definition.
Voice Solutions in Silicon
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