D6455A/B EASYTAD Chip for an all Digital Telephone Answering Device with Super Low Rate Coder and True FULL Duplex SpeakerPhone General Description The D6455A/B chip is a digital speech/signal processing subsystem that implements all functions of TRUESPEECH speech compression and voice prompts, telephone line signal processing, flash memory management and True FULL Duplex SpeakerPhone for an all digital answering machine. The D6455A/B is fully controlled by the system Host through a simple interface protocol. The Host controller provides activation and control of all system functions such as speech recording and playback, DTMF and call progress tone detection, DTMF and tone generation, and voice prompting. Phone Line Telephone Line Interface Speaker Phone Interface CODEC CODEC A Host Controller D6455A/B DSP Speech Processor Voice Prompt ROM ARAM Optional Figure 1. D6455A/B System Block Diagram Key Features n High-quality, new super low rate TRUESPEECH digital speech compression allowing 25-27 minutes of recording time per each 4 Mbit of memory n Flexible storage of incoming messages (ICM), outgoing messages (OGM). Supports multiple OGMs and multiple mailboxes n TRUESPEECH, natural-sound voice prompting, for Day/Time stamp and voice instructions n DTMF generation and detection with near-end echo cancellation for superior performance n Simple 8-bit Host Interface n Fully compatible with the D6305B. Host software compatible, pin-for-pin replaceable n Works with 256Kx4 (1 Mbit)*, 1Mx4 (4 Mbit) or 4Mx4 (16 Mbit)* ARAMs n True FULL Duplex SpeakerPhone with both acoustical and near-end echo cancellation n Programmable Thresholds for VOX, DTMF, and Call Progress n Digital Volume Control n Supports offset playback for jumps within a message n Low power consumption n Special commands for production line testing * Supported in D6455B only A D6455A/B Device Configuration and System Components STANDARD COMPONENTS n D6455A/B-11 Digital Telephone Answering Device (TAD) processor (80-pin PQFP)1 each ADDITIONAL SYSTEM COMPONENTS These are supplied by the customer according to DSP Groups specifications. n D0000-29 Analog I/O Interface (16-pin DIP)1 each, 2 for SpeakerPhone One of the following: n D0000-37C 1-Mbit ARAM Message Memory (SOJ)Up to four devices per system (D6455B only) n D0000-36C 16-Mbit ARAM Message Memory (SOJ)Up to two devices per system (D6455B only), or n D0000-35C 4-Mbit ARAM Message Memory (SOJ)Up to four devices per system OPTIONAL SYSTEM COMPONENTS EPROM/ROM - For Voice Prompt storage an external EPROM/ROM (access time, 300 ms or less) is required -each 32K x 8 block supports 65 seconds of Voice Prompt (up to 64K). C C C N 0 9 8 S N N 7 7 C NI C 8 7 IT 6 N 7 5 7 4 7 G V C 1 0 D D D 1 D A 2 7 8 7 6 D D D D R 0 7 R D A 8 6 R D A 9 7 R D A A 1 7 9 D R R D A 1 1 R D 3 7 2 D R C N 3 1 D 7 6 D A A 6 6 5 6 6 ADDR15 1 64 ADDR5 ADDR14 2 63 ADDR4 ACK 3 62 ADDR3 HI/LO 4 61 ADDR2 HSTRD 5 60 ADDR1 HSTWR 6 59 ADDR0 HSTDB7 7 58 MDB15 HSTDB6 8 57 MDB14 HSTDB5 9 56 NC HSTDB4 10 55 NC HSTDB3 11 54 GND HSTDB2 12 53 VCC HSTDB1 13 52 MDB13 HSTDB0 14 51 MDB12 GND 15 50 MDB11 NC 16 49 MDB10 XOUT 17 48 MDB9 XIN 18 47 MDB8 VCC 19 46 MDB7 SCLK 20 45 MDB6 RESET 21 44 MDB5 22 43 MDB4 FSYNC 23 42 MDB3 DX1 24 41 MDB2 PDN A Top View D6455A-11 5 6 2 2 D X 0 D R 1 7 9 8 2 0 2 2 S 0 R D 4 3 3 3 5 3 3 6 3 1 D C 2 3 R C C G V C C M S A S A N C 8 3 W D R 0 3 4 0 1 D D C R D N N A 9 3 C S A S 7 3 0 A R 2 1 3 R P E Figure 2. D6455A/B Pin Diagram B M B M A D6455A/B System Functions All of the speech processing tasks are done by the DSP Speech Subsystem. This allows the use of a very low cost microcontroller to be used for basic control of the system. The Host need only send high level commands to perform functions such as Record Message or Delete Message and the operation will be performed by the DSP subsystem which will report the status of the operation to the Host. All memory interface and management will be taken care of by the DSP requiring the Host to only handle high level system functions. A summary of the functions performed by the DSP Speech Subsystem and Host Controller are shown in Figure 3, below. DSP Speech Subsystem n n n n n n n n n n Host Controller n Control the System n Read Buttons n Control Displays / Switches Speech Recording Speech Playback Memory / Message Management DTMF and Tone Genertion DTMF Detection Call Process Detection Time / Date Stamping Voice Prompts Phone Number Storage SpeakerPhone Functions Figure 3. System Functions Simple Hardware Interface The hardware interface between the D6455A/B and the Host Controller is a simple one requiring only an 8 bit parallel port and 4 handshake lines. The Host writes high level Commands to the D6455A/B and the D6455A/B will respond with Status information. Once a Command is issued the D6455A/B will use the ACK pin to indicate that the Status is available to be read. The hardware interface between the D6455A/B and Host is shown in Figure 4 below. 8051 Port 0 RD WR HI/LO INT D6455A/B-11 8 HSTD0-7 HSTR HSTW HI/LO ACK Figure 4. D6455A/B / Host Interface Benefits of the D6455A/B n New Super Low Rate TRUESPEECH digital speech compression allowing 25-27 minutes of recording time in only 4 Mbits of memory. This reduces the memory requirement or makes more recording time available in your design n Allows flexibility in design for features such as multiple mailboxes and multiple OGMs allowing design of a product that is truly a Personal Voice Mail System n The Host selectable thresholds for VOX, DTMF, and Call Progress allows for flexibility in design for various countries and different applications n TRUESPEECH natural sounding voice prompts and time/date stamping allow design of a high quality and professional sounding product n The True Full-Duplex SpeakerPhone capability allow a very professional sounding SpeakerPhone to be added to your product with a very minimal additional cost n Flexibility of memory configuration, in the D6455A, allows the use of most readily available and cost effective memory TRUESPEECH is a registered trademark, and True FULL Duplex SpeakerPhone are trademarks of DSP Group, Inc. Other company and product names mentioned in this document may be the trademark or registered trademark of their respective manufacturers. PO-1/96 Printed in USA