isd-t360sb ETC-unknow, isd-t360sb Datasheet - Page 41

• Manufacturer Part Number: isd-t360sb
• Manufacturer: ETC-unknow

2—SOFTWARE
2.1.7
The PDM (Go To Power-Down Mode) command
switches the ISD-T360SB to power-down mode.
The purpose of the PDM command is to save
power during battery operation, or for any other
power saving cause. During power-down mode
only basic functions, such as time and date up-
date, are active (for more details refer to POWER-
DOWN MODE description on page 1-4).
This PDM command may only be issued when the
processor is in IDLE mode (for an explanation of
the ISD-T360SB states, see “The State Machine” on
page 2-1). If it is necessary to switch to power-
down mode from any other state, the controller
must first issue a S (Stop) command to switch the
processor to the IDLE state, and then issue the
PDM command. Sending any command while in
power-down mode resets the VoiceDSP processor
detectors, and returns it to normal operation
mode.
NOTE
2.2
This section provides details of the peripherals in-
terface support functions and their principle oper-
ation. It is divided into the following subjects:
•
•
•
2.2.1
MICROWIRE/PLUS™ is a synchronous serial com-
munication protocol minimizes the number of
ISD
Microcontroller Interface (Slave MICROWIRE)
Memory Interface
Codec Interface
Entering or exiting power-down mode can
distort the real-time clock by up to 500 µs.
Thus, to maintain the accuracy of the real-
time clock, enter or exit the power-down
mode as infrequently as possible.
POWER-DOWN MODE
PERIPHERALS
MICROCONTROLLER INTERFACE
connections, and thus the cost, of communicat-
ing with peripherals.
The VoiceDSP MICROWIRE interface implements
the MICROWIRE/PLUS interface in slave mode, with
an additional ready signal. It enables a microcon-
troller to interface efficiently with the VoiceDSP pro-
cessor application.
The microcontroller is the protocol master and
provides the clock for the protocol. The VoiceDSP
processor supports clock rates of up to 400 KHz.
This transfer rate refers to the bit transfer; the actual
throughput is slower due to byte processing by the
VoiceDSP processor and the microcontroller.
Communication is handled in bursts of eight bits
(one byte). In each burst the VoiceDSP processor
is able to receive and transmit eight bits of data.
After eight bits have been transferred, an internal
interrupt is issued for the VoiceDSP processor to
process the byte, or to prepare another byte for
sending. In parallel, the VoiceDSP processor sets
MWRDY to 1, to signal the microcontroller that it is
busy with the byte processing. Another byte can
be transferred only when the MWRDY signal is
cleared to 0 by the VoiceDSP processor. When the
VoiceDSP processor transmits data, it expects to
receive the value 0xAA before each transmitted
byte. The VoiceDSP processor reports any status
change by clearing the MWRQST signal to 0.
If processor command’s parameter is larger than
one byte, the microcontroller transmits the Most
Significant Byte (MSB) first. If a return value is larger
than one byte, the VoiceDSP processor transmits
the MSB first.
The following signals are used for the interface
protocol. Input and output are relative to the
VoiceDSP processor.
INPUT SIGNALS
MWDIN
MICROWIRE Data In. Used for input only, for trans-
ferring data from the microcontroller to the
VoiceDSP processor.
ISD-T360SB
2-5