CR16MCT9 Datasheet, PDF (5/153 Pages) National Semiconductor (TI) – CR16MCT9/CR16MCT5/CR16HCT9/CR16HCT5 16-Bit Reprogrammable/ROM Microcontroller

3.0 Device Overview
The CR16MCT9/CR16MCT5/CR16HCT9/CR16HCT5 Com-
pactRISC microcontrollers are complete microcomputers
with all system timing, interrupt logic, program memory, data
memory, and I/O ports included on-chip, making it well-suited
to a wide range of embedded controller applications. The
block diagram on page 1 of the data sheet shows the major
on-chip components of the CR16MCT9/CR16MCT5/
CRHCT9/CR16HCT5.
3.1 CR16B CPU CORE
The CR16MCT9/CR16MCT5/CR16HCT9/CR16HCT5 use
the CR16B CPU core module. This is the same core used in
other CompactRISC family member designs, like DECT or
GSM chipsets.
The high performance of the CPU core results from the im-
plementation of a pipelined architecture with a two-bytes-per-
cycle pipelined system bus. As a result, the CPU can support
a peak execution rate of one instruction per clock cycle.
Compared with conventional RISC processors, the
CR16MCT9/CR16MCT5/CR16HCT9/CR16HCT5 differ in
the following ways:
— The CPU core can use on-chip rather than external
memory. This eliminates the need for large and com-
plex bus interface units.
— Most instructions are 16 bits, so all basic instructions
are just two bytes long. Additional bytes are sometimes
required for immediate values, so instructions can be
two or four bytes long.
— Non-aligned word access is allowed. Each instruction
can operate on 8-bit or 16-bit data.
— The device is designed to operate with a clock rate in
the 10 to 24 MHz range rather than 100 MHz or more.
Most embedded systems face EMI and noise con-
straints that limit clock speed to these lower ranges. A
lower clock speed means a simpler, less costly silicon
implementation.
— The instruction pipeline uses three stages. A smaller
pipeline eliminates the need for costly branch predic-
tion mechanisms and bypass registers, while maintain-
ing adequate performance for typical embedded
controller applications.
For more information, please refer to the CR16B Program-
mer’s Reference Manual, Literature #: 633150.
3.2 MEMORY
The CompactRISC architecture supports a uniform linear ad-
dress space of 2 megabytes. The device implementation of
this architecture uses only the lowest 128K bytes of address
space. Four types of on-chip memory occupy specific inter-
vals within this address space:
• 96K bytes of flash EEPROM program memory (100K cy-
cles)
• 4K bytes of static RAM
• 2K bytes of EEPROM data memory with low endurance
(25K cycles)
• 128 bytes EEPROM data memory with high endurance
(100K cycles)
• 1.5K bytes flash EEPROM memory for ISP code
The 4K bytes of static RAM are used for temporary storage
of data and for the program stack and interrupt stack. Read
and write operations can be byte-wide or word-wide, depend-
ing on the instruction executed by the CPU. Each memory
access requires one clock cycle; no wait cycles or hold cycles
are required.
There are two types of flash EEPROM data memory storage.
The 2K bytes of EEPROM data memory with low endurance
(25K cycles) and 128 bytes of flash EEPROM data memory
with high endurance (100K cycles) are used for non-volatile
storage of data, such as configuration settings entered by the
end-user.
The 96K bytes of flash EEPROM program memory are used
to store the application program. It has security features to
prevent unintentional programming and to prevent unautho-
rized access to the program code. This memory can be pro-
grammed with a device external programming unit or with the
device installed in the application system (in-system pro-
gramming).
There is a factory programmed boot memory used to store
In-System-Programming (ISP) code. (This code allows pro-
gramming of the program memory via one of the USART in-
terfaces in the final application.)
For flash EEPROM program and data memory, the device in-
ternally generates the necessary voltages for programming.
No additional power supply is required.
3.3 INPUT/OUTPUT PORTS
The device has 56 software-configurable I/O pins, organized
into seven 8-pin ports called Port B, Port C, Port F, Port G,
Port H, Port I, and Port L. Each pin can be configured to op-
erate as a general-purpose input or general-purpose output.
In addition, many I/O pins can be configured to operate as a
designated input or output for an on-chip peripheral module
such as the USART, timer, A/D converter, or MICROWIRE/
SPI interface.
The I/O pin characteristics are fully programmable. Each pin
can be configured to operate as a TRI-STATE output, push-
pull output, weak pull-up input, or high-impedance input.
3.4 BUS INTERFACE UNIT
The Bus Interface Unit (BIU) controls the interface between
the on-chip modules to the internal core bus. It determines
the configured parameters for bus access (such as the num-
ber of wait states for memory access) and issues the appro-
priate bus signals for each requested access.
The BIU uses a set of control registers to determine how
many wait states and hold states are to be used when ac-
cessing flash EEPROM program memory, ISP memory and
the I/O area (Port B and Port C). Upon start-up the configu-
ration registers are set for slowest possible memory access.
To achieve fastest possible program execution, appropriate
values should be programmed. These settings vary with the
clock frequency and the type of on-chip device being access-
ed.
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