NSAM266SA Datasheet, PDF (9/52 Pages) National Semiconductor (TI) – NSAM266SA CompactSPEECHTM Digital Speech Processor with Serial Flash Interface

1 0 Hardware (Continued)
Consider the following extensive usage of all the
NM29A040’s blocks
1 Record 15 minutes of messages (until the memory is full)
2 Playback 15 minutes (all the recorded messages)
3 Delete all messages
Assuming a NM29A040 device is used in this manner 24
times a day its expected lifetime is
Flash Lifetime e 100 000 (24 365) e 11 4 years
Thus the NM29A040 device will last for over ten years even
when used for six hours of recording per day
Note that if an NM29A080 device is used then under the
same conditions it will last for more than 20 years
ROM Interface
IVS vocabularies can be stored in either serial flash and or
ROM The CompactSPEECH supports IVS ROM devices
through Expansion Memory Up to 64 kbytes (64k x 8) of
Expansion Memory are supported directly Nevertheless
the CompactSPEECH uses bits of the on-chip port (PB) to
further extend the 64 kbytes address space up to
0 5 Mbytes address space
ROM is connected to the CompactSPEECH using the data
bus D(0 7) the address bus A(0 15) the extended address
signals EA(16 18) and Expansion Memory Chip Select
EMCS controls The number of extended address pins to
use may vary depending on the size and configuration of
the ROM
Reading from Expansion Memory
An Expansion Memory read bus-cycle starts at T1 when the
data bus is in TRI-STATE and the address is driven on the
address bus EMCS is asserted (cleared to 0) on a T2W1
cycle This cycle is followed by three T2W cycles and one
T2 cycle The CompactSPEECH samples data at the end of
the T2 cycle
The transaction is terminated at T3 when EMCS becomes
inactive (set to 1) The address remains valid until T3 is
complete A T3H cycle is added after the T3 cycle The
address remains valid until the end of T3H
1 3 6 Codec Interface
The CompactSPEECH provides an on-chip interface to a
serial codec This interface supports codec operation in
long- or short-frame formats The format is selected with the
CFG command
The codec interface uses four signals CDIN CDOUT
CCLK and CFS0
Data is transferred to the codec through the CDOUT pin
Data is read from the codec through the CDIN pin
Data transfer between the CompactSPEECH and the serial
codec starts by the CompactSPEECH asserting (setting to
1) the CFS0 frame synchronization signal After one clock
cycle the CompactSPEECH de-asserts (clears to 0) CFS0
data from the CompactSPEECH is sent to the codec
through CDOUT and simultaneously data from the codec is
sent to the CompactSPEECH through CDIN
Short Frame Protocol
When short frame protocol is configured eight data bits are
exchanged with each codec in each frame i e CFS0 cycle
Data transfer starts when CFS0 is set to 1 for one CCLK
cycle The data is then transmitted bit-by-bit via the
CDOUT output pin Concurrently the received data is shift-
ed in via the CDIN input pin Data is shifted one bit in each
CCLK cycle
Figure 1-6 shows how the codec interface signals behave
when short frame protocol is configured
Long Frame Protocol
When long frame protocol is configured eight data bits are
exhanged with each codec as with the short frame proto-
col However for the long frame protocol data transfer
starts by setting CFS0 to 1 for eight CCLK cycles Simulta-
neously the data for the first codec is shifted out bit-by-bit
via the CDOUT output pin as in short frame protocol Con-
currently the received data is shifted in through the CDIN
input The data is shifted one bit in each CCLK cycle
Figure 1-7 shows how the codec interface signals behave
when long frame protocol is configured
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