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Interrupt Controller

– Interrupt control module

is responsible for the interrupt manage system

for the external and internal interrupt sources.

It contains interrupt related registers such as

Interrupt Enable (IE), Interrupt Priority (IP) and

(TCON) registers.

Timers

– System timers module. Contains two

16 bits configurable timers: Timer 0 (TH0,

TL0), Timer 1 (TH1, TL1) and Timers Mode

(TMOD) registers. In the timer mode, timer

registers are incremented every 12 CLK peri-

ods when appropriate timer is enabled. In the

counter mode the timer registers are incre-

mented every falling transition on their corre-

sponding input pins (T0, T1), if gates are

opened (GATE0, GATE1). T0, T1 input pins

are sampled every CLK period. It can be used

as clock source for UARTs.

UART0

– Universal Asynchronous Receiver &

Transmitter module is full duplex, meaning it

can transmit and receive concurrently. Includes

Serial Configuration register (SCON), serial

receiver and transmitter buffer (SBUF) regis-

ters. Its receiver is double-buffered, meaning it

can commence reception of a second byte

before a previously received byte has been

read from the receive register. Writing to

SBUF0 loads the transmit register, and reading

SBUF0 reads a physically separate receive

register. Works in 3 asynchronous and 1 syn-

chronous modes. UART0 can be synchronized

by Timer 1.

Ports

- Block contains 8051’s general purpose

I/O ports. Each of port’s pin can be read/write

as a single bit or as a 8-bit bus P0, P1, P2, P3.

Power Management Unit

– Block contains

advanced power saving mechanisms with

switchback feature, allowing external clock

control logic to stop clocking (Stop mode) or

run core in lower clock frequency (Power Man-

agement Mode) to significantly reduce power

consumption.

Switchback

feature

allows

UARTs, and interrupts to be processed in full

speed mode if enabled. It is very desired when

microcontroller is planned to use in portable

and power critical applications.

DoCD™ Debug Unit

– it’s a real-time hard-

ware debugger provides debugging capability

of a whole SoC system. In contrast to other on-

chip debuggers DoCD™ provides non-intrusive

debugging of running application. It can halt,

run, step into or skip an instruction, read/write

any contents of microcontroller including all

registers, internal, external, program memo-

ries, all SFRs including user defined peripher-

als. Hardware breakpoints can be set and con-

trolled on program memory, internal and exter-

nal data memories, as well as on SFRs. Hard-

ware breakpoint is executed if any write/read

occurred at particular address with certain data

pattern or without pattern. Two additional pins

CODERUN, DEBUGACS indicate the sate of

the debugger and CPU. CODERUN is active

when CPU is executing an instruction. DE-

BUGACS pin is active when any access is per-

formed by DoCD™ debugger. The DoCD™

system includes JTAG interface and complete

set of tools to communicate and work with core

in real time debugging. It is built as scalable

unit and some features can be turned off to

save silicon and reduce power consumption. A

special care on power consumption has been

taken, and when debugger is not used it is

automatically switched in power save mode.

Finally whole debugger is turned off when de-

bug option is no longer used.

PROGRAM CODE SPACE

IMPLEMENTATIO N

The figure below shows an example Pro-

gram Memory space implementation in sys-

tems with DP8051 Microcontroller core. The

On-chip Program Memory located in address

space between 0kB and 1kB is typically used

for BOOT code with system initialization func-

tions. This part of the code is typically imple-

mented as ROM. The On-chip Program Mem-

ory located in address space between 60kB

and 64kB is typically used for timing critical

part of the code e.g. interrupt subroutines,

arithmetic functions etc. This part of the code is

typically implemented as RAM and can be

loaded by the BOOT code during initialization

phase from Off-chip memory or through RS232

interface from external device. From the two

mentioned above spaces program code is

executed without wait-states and can achieve

a top performance up to 200 million instruc-

tions per second (many instructions executed

in one clock cycle). The Off-chip Program

Memory located in address space between

1kB and 60kB is typically used for main code

and constants. This part of the code is usually

implemented as ROM, SRAM or FLASH de-

vice. Because of relatively long access time

the program code executed from mentioned

above devices must be fetched with additional

Wait-States. Number of required Wait-States