Analog Devices ADSP-BF535 Blackfin, Hardware Reference Manual

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ADSP-BF535 Blackfin Processor Hardware Reference 1-17
Introduction
Timers
There are three general-purpose programmable timer units in the
ADSP-BF535 processor. Each timer has one external pin that can be con-
figured either as a Pulse Width Modulator (PWM) or timer output, as an
input to clock the timer, or for measuring pulse widths of external events.
Each of the three timer units can be independently programmed as a
PWM, internally or externally clocked timer, or pulse width counter.
The timer units can be used in conjunction with either of the UARTs to
measure the width of the pulses in the data stream to provide an autobaud
detect function for a serial channel.
The timers can generate interrupts to the processor core to provide peri-
odic events for synchronization, either to the processor clock or to a count
of external signals.
In addition to the three general-purpose programmable timers, a fourth
timer is also provided. This extra timer is clocked by the internal processor
clock and is typically used as a system tick clock for generation of operat-
ing system periodic interrupts.
The ADSP-BF535 processor uses a programmable interval timer to gener-
ate periodic interrupts. An 8-bit prescale register sets the number of clock
cycles for decrementing a 32-bit count register. The number of clock
cycles per timer decrement can be from 1 to 256. An interrupt is gener-
ated when this count register reaches 0. The count register can be
automatically reloaded from a 16-bit period register and the count
resumed.
Serial Ports (SPORTs)
The ADSP-BF535 processor incorporates two complete synchronous
serial ports (SPORT0 and SPORT1) for serial and multiprocessor com-
munications. The SPORTs support these features: