DM5210 analog input module 3-3 RTD Embedded Technologies, Inc.
DC/DC
CONVERTER
±15 VOLTS
+5 VOLTS
5
PC
BUS
DATA
8
8
8
INTERRUPT
SELECT
12-BIT
A/D
CONVERTER
PORT B
PORT A
PORT C
8254
PIT
ADDRESS
ADDRESS
DECODE
CONTROL
TIMER/
COUNTER
I/O
SELECT
8 MHz
OSC
RANGE
SELECT
±5 V
0 TO +10 V
±10 V
RESISTOR
CONFIG.
GAIN
MUX
PULL-UP/DOWN
RESISTORS
16 ANALOG
INPUTS
±5V
0 - +10V
±10V
+5 VOLTS
CONTROL
±12 VOLTS
S/H
EOC
I/
O
CO
NNECT
O
R
8255
PPI
16
ON-BOARD
HEADER
4
The 210/5210 has three major circuits, the A/D, the timer/counters, and the 8255 programmable peripheral
interface (PPI) which provides the digital I/O lines. Figure 3-1 shows the block diagram of the module. This chapter
describes hardware which makes up the major circuits. It also discusses interrupts.
A/D Conversion Circuitry
The 210/5210 performs analog-to-digital conversions on up to 16 analog input channels. The following para-
graphs describe the A/D circuitry.
Analog Inputs
Sixteen single-ended analog input channels are available on the 210/5210. The analog input range is jumper-
selectable for -5 to +5 volts, -10 to +10 volts, or 0 to +10 volts, with ±35 Vdc overvoltage protection. The channels
are connected to a sample-and-hold amplifier through a multiplexing circuit. The active channel is selected through
software, as described in Chapter 4.
The S/H amplifier captures and holds the input signal at a constant level while the conversion is performed,
ensuring that dynamic analog signals are accurately digitized. This capacitive circuit quickly charges to a level
corresponding to the input voltage being sampled and holds the charge for the duration of the conversion.
A/D Converter
The 12-bit A/D converter , when combined with the typical acquisition time of the sample-and-hold circuitry,
provides a throughput rate of up to 40,000 samples per second. The A/D output is a 12-bit data word. Note that 8-bit
conversions can be performed when speed is more critical than resolution. Eight-bit conversions can increase the
throughput rate to about 45 kHz.
Fig. 3-1 — DM210/DM5210 Block Diagram
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