CC2531F128_12 Datasheet, PDF (20/35 Pages) Texas Instruments – A USB-Enabled System-On-Chip Solution for 2.4-GHz IEEE 802.15.4 and ZigBee

CC2531F128, CC2531F256
SWRS086A – SEPTEMBER 2009 – REVISED JUNE 2010
www.ti.com
Timer 1 is a 16-bit timer with timer/counter/PWM functionality. It has a programmable prescaler, a 16-bit period
value, and five individually programmable counter/capture channels, each with a 16-bit compare value. Each of
the counter/capture channels can be used as a PWM output or to capture the timing of edges on input signals. It
can also be configured in IR Generation Mode, where it counts Timer 3 periods and the output is ANDed with
the output of Timer 3 to generate modulated consumer IR signals with minimal CPU interaction.
Timer 2 (the MAC Timer) is specially designed for supporting an IEEE 802.15.4 MAC or other time-slotted
protocol in software. The timer has a configurable timer period and a 24-bit overflow counter that can be used to
keep track of the number of periods that have transpired. A 40-bit capture register is also used to record the
exact time at which a start-of-frame delimiter is received/transmitted or the exact time at which transmission
ends, as well as two 16-bit output compare registers and two 24-bit overflow compare registers that can send
various command strobes (start RX, start TX, etc.) at specific times to the radio modules.
Timer 3 and Timer 4 are 8-bit timers with timer/counter/PWM functionality. They have a programmable
prescaler, an 8-bit period value, and one programmable counter channel with an 8-bit compare value. Each of
the counter channels can be used as a PWM output.
The sleep timer is an ultralow-power timer that counts 32-kHz crystal oscillator or 32-kHz RC oscillator periods.
The sleep timer runs continuously in all operating modes except power mode 3 (PM3). Typical applications of
this timer are as a real-time counter or as a wake-up timer to come out of power mode 1 (PM1) or 2 (PM2).
The ADC supports 7 to 12 bits of resolution in a 30-kHz to 4-kHz bandwidth, respectively. DC and audio
conversions with up to eight input channels (Port 0) are possible. The inputs can be selected as single-ended or
differential. The reference voltage can be internal, AVDD, or a single-ended or differential external signal. The
ADC also has a temperature-sensor input channel. The ADC can automate the process of periodic sampling or
conversion over a sequence of channels.
The random-number generator uses a 16-bit LFSR to generate pseudorandom numbers, which can be read by
the CPU or used directly by the command strobe processor. It can be seeded with random data from noise in the
radio ADC.
The AES encryption/decryption core allows the user to encrypt and decrypt data using the AES algorithm with
128-bit keys. The core is able to support the AES operations required by IEEE 802.15.4 MAC security, the
ZigBee network layer, and the application layer.
A built-in watchdog timer allows the CC2531 to reset itself in case the firmware hangs. When enabled by
software, the watchdog timer must be cleared periodically; otherwise, it resets the device when it times out. It can
alternatively be configured for use as a general 32-kHz timer.
USART 0 and USART 1 are each configurable as either a SPI master/slave or a UART. They provide double
buffering on both RX and TX and hardware flow control, and are thus well suited to high-throughput full-duplex
applications. Each has its own high-precision baud-rate generator, thus leaving the ordinary timers free for other
uses.
The USB device operates at full-speed, 12-Mbps transfer rate. The controller has 5 bidirectional endpoints in
addition to control endpoint 0. The endpoints support bulk, interrupt, and isochronous operation for
implementation of a wide range of applications. The 1024 bytes of dedicated, flexible FIFO memory combined
with DMA access ensures that a minimum of CPU involvement is needed for USB communication.
Radio
The CC2531 features an IEEE 802.15.4-compliant radio transceiver. The RF core controls the analog radio
modules. In addition, it provides an interface between the MCU and the radio which makes it possible to issue
commands, read status, and automate and sequence radio events. The radio also includes a packet-filtering and
address-recognition module.
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