Appendix D. Sample Circuits

This appendix details several basic sample circuits that can be used with the RabbitCore RCM2200 modules.

• RS-232/RS-485 Serial Communication

• Keypad and LCD Connections

• Keypad and LCD Connections

• D/A Converter

D.1 RS-232/RS-485 Serial Communication

Figure D-1: Sample RS-232 and RS-485 Circuits

Sample Program: PUTS.C in SAMPLES/RCM2200.

D.2 Keypad and LCD Connections

Figure D-2: Sample Keypad Connections

Sample Program: KEYLCD.C in SAMPLES/RCM2200.

Figure D-3: Sample LCD Connections

Sample Program: KEYLCD.C in SAMPLES/RCM2200.

D.3 External Memory

The sample circuit can be used with an external 64K memory device. Larger SRAMs can be written to using this scheme by using other available Rabbit 2000 ports (parallel ports A to E) as address lines.

Figure D-4: Sample External Memory Connections

Sample Program: EXTSRAM.C in SAMPLES/RCM2200.

D.4 D/A Converter

The output will initially be 0 V to -10.05 V after the first inverting op-amp, and 0 V to +10.05 V after the second inverting op-amp. All lows produce 0 V out, FF produces 10 V out. The output can be scaled by changing the feedback resistors on the op-amps. For example, changing 5.11 kW to 2.5 kW will produce an output from 0 V to -5 V. Op-amps with a very low input offset voltage are recommended.

Figure D-5: Sample D/A Converter Connections