National CP3BT26 - Manual (Page 6)

www.national.com 6
CP3BT26
3.14 RANDOM NUMBER GENERATOR
RNG peripheral for use in Trusted Computer Peripheral Ap-
plications (TCPA) to improve the authenticity, integrity, and
privacy of Internet-based communication and commerce.
3.15 MICROWIRE/SPI
The Microwire/SPI (MWSPI) interface module supports syn-
chronous serial communications with other devices that
conform to Microwire or Serial Peripheral Interface (SPI)
specifications. It supports 8-bit and 16-bit data transfers.
The Microwire interface allows several devices to communi-
cate over a single system consisting of four wires: serial in,
serial out, shift clock, and slave enable. At any given time,
the Microwire interface operates as the master or a slave.
The Microwire interface supports the full set of slave select
for multi-slave implementation.
In master mode, the shift clock is generated on-chip under
software control. In slave mode, a wake-up out of a low-
power mode may be triggered using the Multi-Input Wake-
Up module.
3.16 ACCESS.BUS INTERFACE
The ACCESS.bus interface module (ACB) is a two-wire se-
rial interface compatible with the ACCESS.bus physical lay-
er. It is also compatible with Intel’s System Management
Bus (SMBus) and Philips’ I
2 C bus. The ACB module can be
configured as a bus master or slave, and it can maintain bi-
directional communications with both multiple master and
slave devices.
The ACCESS.bus receiver can trigger a wake-up condition
out of the low-power modes through the Multi-Input Wake-
Up module.
3.17 MULTI-FUNCTION TIMER
The Multi-Function Timer (MFT) module contains a pair of
16-bit timer/counter registers. Each timer/counter unit can
be configured to operate in any of the following modes:
— Processor-Independent Pulse Width Modulation
(PWM) mode: Generates pulses of a specified width
and duty cycle and provides a general-purpose timer/
counter.
— Dual Input Capture mode: Measures the elapsed time
between occurrences of external event and provides
a general-purpose timer/counter.
— Dual Independent Timer mode: Generates system
timing signals or counts occurrences of external
events.
— Single Input Capture and Single Timer mode: Pro-
vides one external event counter and one system tim-
er.
3.18 TIMING AND WATCHDOG MODULE
The Timing and Watchdog Module (TWM) contains a Real-
Time timer and a Watchdog unit. The Real-Time Clock Tim-
ing function can be used to generate periodic real-time
based system interrupts. The timer output is one of 16 in-
puts to the Multi-Input Wake-Up module which can be used
to exit from a power-saving mode. The Watchdog unit is de-
signed to detect the application program getting stuck in an
infinite loop resulting in loss of program control or “runaway”
programs. When the watchdog triggers, it resets the device.
The TWM is clocked by the low-speed System Clock.
3.19 VERSATILE TIMER UNIT
The Versatile Timer Unit (VTU) module contains four inde-
pendent timer subsystems, each operating in either dual 8-
bit PWM configuration, as a single 16-bit PWM timer, or a
16-bit counter with two input capture channels. Each of the
four timer subsystems offer an 8-bit clock prescaler to ac-
commodate a wide range of frequencies.
3.20 TRIPLE CLOCK AND RESET
The Triple Clock and Reset module generates a high-speed
main System Clock from an external crystal network. It also
provides the main system reset signal and a power-on reset
function.
This module generates a slow System Clock (32.768 kHz)
from an optional external crystal network. The Slow Clock is
used for operating the device in a low-power mode. The
32.768 kHz external crystal network is optional, because
the low speed System Clock can be derived from the high-
speed clock by a prescaler. Also, two independent clocks di-
vided down from the high speed clock are available on out-
put pins.
The Triple Clock and Reset module provides the clock sig-
nals required for the operation of the various CP3BT26 on-
chip modules. From external crystal networks, it generates
the Main Clock, which can be scaled up to 24 MHz from an
external 12 MHz input clock, and a 32.768 kHz secondary
System Clock. The 12 MHz external clock is primarily used
as the reference frequency for the on-chip PLL. The clock
for modules which require a fixed clock rate (e.g. the Blue-
tooth LLC and the CVSD/PCM transcoder) is also generat-
ed through prescalers from the 12 MHz clock. The PLL may
be used to drive the high-speed System Clock through a
prescaler. Alternatively, the high speed System Clock can
be derived directly from the 12 MHz Main Clock.
In addition, this module generates the device reset by using
reset input signals coming from an external reset and vari-
ous on-chip modules.