Timer Module - Motorola DSP56309 User Manual

DSP56309 Overview
DSP56309 Architecture Overview
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 the 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 DSP56309 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 so that the baud-rate generator can 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 Module

The triple timer module is composed of a common 21-bit prescaler and three
independent and identical general-purpose 24-bit timer/event counters, each with its
own memory-mapped register set.
Each timer has a single signal that can function as a GPIO signal or as a timer signal.
Each timer can use internal or external clocking and 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 measures external pulse width/signal period. When the signal is used
as an output, the timer can function as either a timer, a watchdog, or a Pulse Width
Modulator (PWM).
MOTOROLA DSP56309UM/D 1-17