ADUC832 Analog Devices, ADUC832 Datasheet - Page 87

• Manufacturer Part Number: ADUC832
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 62kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC832

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 8
• Other: PWM

OTHER HARDWARE CONSIDERATIONS
To facilitate in-circuit programming, plus in-circuit debug and
emulation options, implement some simple connection points
in the hardware that allow easy access to download, debug, and
emulation modes.
IN-CIRCUIT SERIAL DOWNLOAD ACCESS
Nearly all ADuC832 designs can take advantage of the in-circuit
reprogrammability of the chip. This is accomplished by a
connection to the ADuC832 UART, which requires an external
RS-232 chip for level translation if downloading code from a
PC. Basic configuration of an RS-232 connection is illustrated
in Figure 94 with a simple ADM202-based circuit. To avoid
designing an RS-232 chip onto a board, refer to the uC006
Technical Note, A 4-Wire UART-to-PC Interface, available at
www.analog.com, for a simple (and zero-cost-per-board)
method of gaining in-circuit serial download access to the
ADuC832.
In addition to the basic UART connections, users also need a way
to trigger the chip into download mode. This is accomplished via a
1 kΩ pull-down resistor that can be jumpered onto the PSEN
pin, as shown in
mode, connect this jumper and power-cycle the device (or
manually reset the device, if a manual reset button is available)
so that it can receive a new program serially. With the jumper
removed, the device comes up in normal mode (and runs the
program) whenever power is cycled or RESET is toggled.
Note that PSEN is normally an output (as described in the
External Memory Interface
only on the falling edge of RESET (that is, at power-up or upon
an external manual reset). Note also that if any external circuitry
unintentionally pulls
may cause the chip to enter download mode and therefore fail
to begin user code execution as it should. To prevent this, ensure
that no external signals are capable of pulling the PSEN pin low,
except for the external PSEN jumper itself.
Figure 94
PSEN low during power-up or reset events, it
. To put the ADuC832 into download
section) and is sampled as an input
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EMBEDDED SERIAL PORT DEBUGGER
From a hardware perspective, entry into serial port debug mode
is identical to the serial download entry sequence described in
the In-Circuit Serial Download Access section. In fact, both
serial download and serial port debug modes can be thought of
as essentially one mode of operation used in two different ways.
Note that the serial port debugger is fully contained on the
ADuC832 device (unlike ROM monitor type debuggers) and
therefore no external memory is needed to enable in-system
debug sessions.
SINGLE-PIN EMULATION MODE
Also built into the ADuC832 is a dedicated controller for single-pin
in-circuit emulation (ICE) using standard production ADuC832
devices. In this mode, emulation access is gained by connection
to a single pin, the EA pin. Normally, this pin is hardwired
either high or low to select execution from internal or external
program memory space. To enable single-pin emulation mode,
however, users need to pull the EA pin high through a 1 kΩ
resistor, as shown in
the 2-pin header, also shown in
the standard connector that comes with the single-pin emulator,
use a 2-pin 0.1 inch pitch friction lock header from Molex such as
Part Number 22-27-2021. Be sure to observe the polarity of this
header. As represented in
located on the right, the ground pin should be the lower of the
two pins (when viewed from the top).
TYPICAL SYSTEM CONFIGURATION
A typical ADuC832 configuration is shown in Figure 94. It
summarizes some of the hardware considerations discussed in
the Single-Pin Emulation Mode section.
Figure 94
Figure 94
. The emulator then connects to
Figure 94
, when the friction lock tab is
. To be compatible with
ADuC832