Rabbit OP7100 User Manual download pdf (Page 30)

24 eDisplay (OP7200)

3.4 Analog Features (OP7200 only)

The single A/D converter used in the OP7200 (the OP7210 does not have analog or touch-

screen capabilities) has a resolution of 11 bits (single-ended mode) or 12 bits (differential

mode). There are eight channels of A/D conversion, and the OP7200 also has provision

for up to four digital inputs. Three of the four digital inputs are available on screw terminal

header J2. The fourth digital input serves as a board status bit, and is controlled by a 0 Ω

surface-mount resistor R159. The factory default is for R159 to not be installed, which

leaves this fourth input pulled up to Vcc.

3.4.1 A/D Converter Inputs

Figure 11 shows a pair of A/D converter input circuits. Each A/D converter input consists

of resistors and a capacitor. The resistors form a10:1 attenuator, and the capacitor protects

the A/D converter input against electrostatic discharges.

Figure 11. A/D Converter Inputs

180 kW

AIN0

AGND

+ V

AIN1

ADC

Factory

Default

2.048 V

0 W

180 kW

1 nF

20 kW

1 nF

ADC

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Rabbit OP7100 User Manual Page 30