wts701 Winbond Electronics Corp America, wts701 Datasheet - Page 23

• Manufacturer Part Number: wts701
• Description: Winbond Single-chip Text-to-speech Processor
• Manufacturer: Winbond Electronics Corp America

The byte count register (BCNT) is a tool for the host to keep track of where in a conversion the
WTS701 is. When a new conversion is started, the byte count register is reset to zero. As each word
(as defined by white-space separated characters) is spoken, the byte count register is updated to
point to the first character of the next word to be spoken. In this way, the host can position a new
conversion if the user wishes to repeat or skip text. The BCNT register is sent with BCNT1 (MSB) first
and BCNT0 (LSB) second.
The WTS701 processes commands and data as they are sent to the device. Under certain conditions
the device will not be ready to accept a new command or data. If the device has not finished
processing the previous command, the ICMD bit of the status register will be set. If this bit is set, it
implies that device is not in a position to accept the command being sent and that it will be ignored.
The host should monitor this bit when a command is sent and, if it is detected, the SPI transaction
should be terminated at the end of the command word. The host can then resend the command until
the command is accepted.
The WTS701 has an eight byte FIFO to buffer data from the SPI port to the internal processor. During
a conversion, data is read from this FIFO into an internal RAM data buffer. If SPI transmission is too
fast for the WTS701 to keep up with, the R/ B line will be asserted (LOW) to pause data transfer.
Alternatively, the STATUS register can be monitored for the state of the R/ B signal.
Control of the WTS701 is implemented through a 16-bit command word. The command word is
always the first word to follow the falling edge on the SS signal. The command word consists of the
command byte followed by the command data byte. Many commands do not require a command data
byte, although one must be sent. For commands that have no data, the command data byte is a ‘don’t
care’.
Commands fall into five categories. Commands that control an operational synthesis function of the
text-to-speech processing, commands that modify internal configuration registers, commands that
change system state, commands that read internal status registers, and customization commands.
7.4 C
7.3.4 BCNT -- Byte Count Register
7.3.5 Command Acceptance
7.3.6 Data Acceptance
OMMANDS
O
VERVIEW
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Publication Release Date: May 2003
WTS701
Revision 3.09