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. It works in 3 asynchronous and 1 syn-
chronous modes. UART0 can be synchronized
by Timer 1 or Timer 2.
UART1
– Universal Asynchronous Receiver &
Transmitter module is full duplex, meaning it
can transmit and receive concurrently. Includes
Serial Configuration register (SCON1), serial
receiver and transmitter buffer (SBUF1) 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
SBUF1 loads the transmit register, and reading
SBUF1 reads a physically separate receive
register. It works in 3 asynchronous and 1 syn-
chronous modes. UART1 is synchronized by
Timer 1.
Master I2C Unit
– I2C bus controller is a Mas-
ter module. The core incorporates all features
required by I2C specification. It supports both
7-bit and 10-bit addressing modes on the I2C
bus. It works as a master transmitter and re-
ceiver. It can be programmed to operate with
arbitration and clock synchronization to allow it
operates in multi-master systems. Built-in timer
allows operation from a wide range of the input
frequencies. The timer allows achieving any
non-standard clock frequency. The I2C control-
ler supports all transmission modes: Standard,
Fast and High Speed up to 3400 kbps.
Slave I2C Unit
– I2C bus controller is a Slave
module. The core incorporates all features
required by I2C specification. It works as a
slave transmitter/receiver depending on work-
ing mode determined by a master device. The
I2C controller supports all transmission modes:
Standard, Fast and High Speed up to 3400
kbs.
SPI Unit
– it’s a fully configurable master/slave
Serial Peripheral Interface, which allows user
to configure polarity and phase of serial clock
signal SCK. It allows the microcontroller to
communicate with serial peripheral devices. It
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is also capable of interprocessor communica-
tions in a multi-master system. A serial clock
line (SCK) synchronizes shifting and sampling
of the information on the two independent se-
rial data lines. SPI data are simultaneously
transmitted and received. SPI system is flexi-
ble enough to interface directly with numerous
standard product peripherals from several
manufacturers. Data rates as high as CLK/4.
Clock control logic allows a selection of clock
polarity and a choice of two fundamentally dif-
ferent clocking protocols to accommodate most
available synchronous serial peripheral de-
vices. When the SPI is configured as a master,
software selects one of four different bit rates
for the serial clock. SPI automatically drives
slave select outputs SSO[7:0], and address
SPI slave device to exchange serially shifted
data. Error-detection logic is included to sup-
port interprocessor communications. A write-
collision detector indicates when an attempt is
made to write data to the serial shift register
while a transfer is in progress. A multiple-
master mode-fault detector automatically dis-
ables SPI output drivers if more than one SPI
devices simultaneously attempts to become
bus master.
PROGRAM CODE SPACE
IMPLEMENTATION
The figure below shows an example Pro-
gram Memory space implementation in sys-
tems with DP8051XP 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-
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