Serial Communications Interface (Sci); Timer/Event Counter (Tec) - Motorola DSP56305 User Manual

1.10.4

Serial Communications Interface (SCI)

The DSP56305's Serial Communications Interface (SCI) provides a full-duplex port for
serial communication to other DSPs, microprocessors, or peripherals such as modems.
The SCI interfaces without additional logic to peripherals that use TTL-level signals.
With a small amount of additional logic, the SCI can connect to peripheral interfaces that
have non-TTL level signals, such as RS-232C, RS-422, etc.
This interface uses three dedicated signals: Transmit Data (TXD), Receive Data (RXD),
and SCI Serial Clock (SCLK). It supports industry-standard asynchronous bit rates and
protocols, as well as high-speed synchronous data transmission (up to 8.25 Mbps for a 66
MHz clock). The asynchronous protocols supported by the SCI include a Multidrop
mode for master/slave operation with Wakeup On Idle Line and Wakeup On Address
Bit capability. This mode allows the DSP56305 to share a single serial line efficiently with
other peripherals.
The SCI consists of separate transmit and receive sections that can operate
asynchronously with respect to each other. A programmable baud-rate generator
provides the transmit and receive clocks. An enable vector and an interrupt vector have
been included, allowing the baud-rate generator to function as a general purpose timer
when it is not being used by the SCI, or when the interrupt timing is the same as that
used by the SCI.
1.10.5

Timer/Event Counter (TEC)

The Timer/Event Counter is composed of a common 21-bit prescaler and three
identical independent general purpose 24-bit timer/event counters. Each counters has
its own memory-mapped register set.
Each timer has a single signal that can be used as a GPIO signal or as a timer signal. Each
timer can use internal or external clocking; each timer can interrupt the DSP after a
specified number of events (clocks) or can signal an external device after counting
internal events. Each timer connects to the external world through one bidirectional
signal. When this signal is configured as an input, the timer can function as an external
event counter or measure external pulse width/signal period. When the signal is used as
an output, the timer can function as a timer, a watchdog, or a Pulse Width Modulator
(PWM).
MOTOROLA DSP56305 User's Manual
DSP56305 Overview
DSP56305 Architecture Overview
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