ADUC824 Analog Devices, ADUC824 Datasheet - Page 66

• Manufacturer Part Number: ADUC824
• Description: Precision Analog Microcontroller: 1MIPS 8052 MCU + 8kB Flash + 16/24-Bit ADC + 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC824

• Mcu Core: 8052
• Mcu Speed (mips): 1
• Sram (bytes): 256Bytes
• Gpio Pins: 34
• Adc # Channels: 4

ADuC824
comes with the single-pin emulator available from Accutron Limited
(www.accutron.com), use a 2-pin 0.1-inch pitch “Friction Lock”
header from Molex (www.molex.com) such as their part number
22-27-2021. Be sure to observe the polarity of this header. As
represented in Figure 53, when the Friction Lock tab is at the
right, the ground pin should be the lower of the two pins (when
viewed from the top).
Enhanced-Hooks Emulation Mode
ADuC824 also supports enhanced-hooks emulation mode. An
enhanced-hooks-based emulator is available from Metalink
Corporation (www.metaice.com). No special hardware support
for these emulators needs to be designed onto the board since
these are “pod-style” emulators where users must replace the chip
on their board with a header device that the emulator pod plugs
into. The only hardware concern is then one of determining if
adequate space is available for the emulator pod to fit into the
system enclosure.
Typical System Configuration
A typical ADuC824 configuration is shown in Figure 53. It sum-
marizes some of the hardware considerations discussed in the
previous paragraphs.
DV
RTD
5.6k
DD
510
R1
R2
V
CC
200 A/400 A
EXCITATION
CURRENT
ADM810
GND
V
V
A
A
REF
REF
IN
IN
AV
C1+
V+
C1–
C2+
C2–
V–
T2OUT
R2IN
+
–
RST
DD
+
–
ADM202
R1OUT
R2OUT
T1OUT
GND
R1IN
T1IN
T2IN
V
CC
P1.2I
AV
AGND
REFIN–
REFIN+
P1.4/AIN1
P1.5/AIN2
52
DD
DV
EXC
51 50
DD
1/DAC
49
DV
48
DD
DV
47
DD
Figure 53 also includes connections for a typical analog mea-
surement application of the ADuC824, namely an interface to
an RTD (Resistive Temperature Device). The arrangement
shown is commonly referred to as a 4-wire RTD configuration.
Here, the on-chip excitation current sources are enabled to excite
the sensor. An external differential reference voltage is generated
by the current sourced through resistor R1. This current also
flows directly through the RTD, which generates a differential
voltage directly proportional to temperature. This differential
voltage is routed directly to the positive and negative inputs of
the primary ADC (AIN1, AIN2 respectively). A second external
resistor, R2, is used to ensure that absolute analog input voltage
on the negative input to the primary ADC stays within that
specified for the ADuC824, i.e., AGND + 100 mV.
It should also be noted that variations in the excitation current
do not affect the measurement system as the input voltage from
the RTD and reference voltage across R1 vary ratiometrically with
the excitation current. Resistor R1 must, however, have a low
temperature coefficient to avoid errors in the reference voltage
over temperature.
9-PIN D-SUB
46
FEMALE
45
DOWNLOAD/DEBUG
(NORMALLY OPEN)
1
3
4
6
7
8
2
5
9
44 43
ENABLE JUMPER
1k
42
NOT CONNECTED IN THIS EXAMPLE
41
XTAL2
XTAL1
DGND
DV
1k
40
DD
DV
38
37
36
34
27
39
35
33
32
31
30
29
28
DD
DV
32.766kHz
DD
2-PIN HEADER FOR
EMULATION ACCESS
(NORMALLY OPEN)