It is not referenced to | Digi RCM4000 specification

If a device such as a battery is

connected across two channels

R5

for a differential measurement,

AIN0

LN0 ADC

and it is not referenced to

2.2 nF

R13

analog ground, then the current

Device

+

I

from the device will flow

-

+

through both sets of attenuator

2.2 nF

R14

resistors as shown in Figure 11.

AIN1

R6

–

LN1

This will generate a negative

voltage at one of the inputs,

Figure 11. Current Flow from Ungrounded

LN1, which will almost cer-

tainly lead to inaccurate A/D

or Floating Source

conversions. To make such dif-

ferential measurements, connect the R1 resistors to the A/D converter’s internal reference voltage, which is software-configurable for 1.15 V, 2.048 V, or 2.5 V. This internal reference voltage is available on pin 49 of header J3 as VREF, and allows you to convert analog input voltages that are negative with respect to analog ground.

NOTE: The amplifier inside the A/D converter’s internal voltage reference circuit has a very limited output-current capability. The internal buffer can source up to 20 mA and sink only up to 20 µA. Use a separate buffer amplifier if you need to supply any load current.

The A/D converter’s CONVERT pin is available on pin 48 of header J3 and can be used as a hardware means of forcing the A/D converter to start a conversion cycle. The CONVERT signal is an edge-triggered event and has a hold time of two CCLK periods for debounce.

A conversion is started by an active (rising) edge on the CONVERT pin. The CONVERT pin must stay low for at least two CCLK periods before going high for at least two CCLK periods. Figure 12 shows the timing of a conversion start. The double falling arrow on CCLK indicates the actual start of the conversion cycle.

Conversion starts

CCLK

BUSY

CONV

Figure 12. Timing Diagram for Conversion Start Using CONVERT Pin

Appendix B explains the implementation examples of these features on the Prototyping Board.

36	RabbitCore RCM4000

Image 42

Digi RCM4000 user manual It is not referenced to

Contents

RabbitCore RCM4000 Trademarks Rabbit Semiconductor Table of Contents Software Reference Appendix C. Power Supply 109 RabbitCore RCM4100 Introduction RCM4000 Features RCM4000 FeaturesFeature RCM4000 RCM4010 Advantages of the RCM4000 Development and Evaluation Tools 1 RCM4000 Development Kit Software Online Documentation RabbitCore RCM4000 Install Dynamic C Getting Started Hardware Connections Prepare the Prototyping Board for Development Attach Module to Prototyping Board Prototyping Board AC Adapter Connect Programming Cable Connect Power Troubleshooting Run a Sample ProgramRun a Sample Program Where Do I Go From Here? Technical Support RabbitCore RCM4000 Running Sample Programs Introduction Sample Programs User’s Manual Use of Nand Flash RCM4000 only Click OK or Close to exit the various dialog boxes Serial Communication User’s Manual 3 A/D Converter Inputs RCM4000 only Real-Time Clock Hardware Reference RabbitCore Module RCM4000 Digital Inputs and Outputs Shows the RCM4000 pinouts for header J3 4000 RCM4000 Pinout Configurations Pin Pin Name Default Use Alternate Use TXD PC0 PE1 Memory I/O Interface Other Inputs and Outputs Rabbit 4000 Serial Port and Clock Pins Serial CommunicationSerial Ports Ethernet Port RJ-45 Ethernet Port Pinout Programming Port Changing Between Program Mode and Run Mode Programming Cable Standalone Operation of the RCM4000 A/D Converter RCM4000 only Resistor Divider Network for Analog Inputs It is not referenced to 1 A/D Converter Power Supply Analog Supply Circuit Other Hardware Clock DoublerSpectrum Spreader Flash Eprom MemorySram Nand Flash RabbitCore RCM4000 Software Reference More About Dynamic C RabbitCore RCM4000 Serial Communication Drivers Dynamic C Function CallsDigital I/O Sram Use RabbitCore RCM4000 Prototyping Board Functions Board Initialization Void timedAlertunsigned long timeout Alerts ADS7870 Signal ADS7870 State RCM3400 Function/State Analog Inputs RCM4000 only On write operations Data value on read operations Unsigned int anaInDriverunsigned int cmd, unsigned int len Gain Code Multiplier AnaInConfig, anaIn, brdInit Single Diff Gain Code Multiplier Voltage Range ×10 ×16 ×20 126 Applies to Prototyping Board If successful If not able to make calibration constants Float anaInVoltsunsigned int channel, unsigned int gaincode Channel Code Single-Ended Voltage Range † Input Lines Float anaInDiffunsigned int channel, unsigned int gaincode Float anaInmAmpsunsigned int channel Channel Code 20 mA Input Lines Allchan Gain Code Voltage Range +AIN7 AIN6 Gain Code Voltage Range Upgrading Dynamic C Add-On Modules RabbitCore RCM4000 Using the TCP/IP Features TCP/IP Connections RabbitCore RCM4000 TCP/IP Primer on IP Addresses Typical Corporate Network IP Addresses Explained How IP Addresses are Used Dynamically Assigned Internet Addresses Placing Your Device on the Network Direct Connection Using a Hub Running TCP/IP Sample ProgramsDirect Connection How to Set IP Addresses in the Sample Programs How to Set Up your Computer for Direct Connect Direct Connection PC to RCM4000 Module Run the PINGME.C Sample Program Running Additional Sample Programs With Direct Connect Where Do I Go From Here? RabbitCore RCM4000 Appendix A. RCM4000 Specifications Electrical and Mechanical Characteristics Dia × Exclusion Zone Table A-1. RCM4000 Specifications Parameter RCM4000 RCM4010 Ten 8-bit timers 6 cascadable from the first Table A-2 Converter Specifications 1 A/D ConverterParameter Test Conditions Headers Figure A-3. User Board Footprint for RCM4000 Symbol Parameter Maximum Rating Rabbit 4000 DC CharacteristicsTable A-4 .3 Volt DC Characteristics Symbol Parameter Min Typ Max Table A-5. Capacitance of Rabbit 4000 I/O Ports I/O Buffer Sourcing and Sinking LimitBus Loading Table A-6. External Capacitive Bus Loading -40C to +85C Iord 30 pF 60 pF 90 pF Ns setting No dbl / dbl Table A-8. Preliminary Data and Clock DelaysOutput Delay Clock to Address Worst-Case Conformal Coating Conformally coated Area Jumper Configurations Table A-9. RCM4000 Jumper ConfigurationsHeader Description Pins Connected Factory Default RabbitCore RCM4000 Appendix B. Prototyping Board Current Measurement Headers RCM4000 Prototyping Board Features RabbitCore RCM4000 Mechanical Dimensions and Layout 935 Power Supply Table B-1. Prototyping Board SpecificationsParameter Specification Using the Prototyping Board Signals Pin Pin Name Prototyping Board Use Adding Other Components Measuring Current Draw Analog Features RCM4000 only Table B-3. Positive A/D Converter Input Voltage Ranges3.1 A/D Converter Inputs Table B-4. Differential Voltage Ranges Mode Read Calibrate Thermistor Input3.3 A/D Converter Calibration Table B-5. Prototyping Board Serial Port Configurations Serial Port Header Default Use Alternate Use 4.1 RS-232 Prototyping Board Jumper Configurations Table B-6. RCM3400 Prototyping Board Jumper Configurations JP5 LN4IN-LN6IN 108 Appendix C. Power Supply Power SuppliesBattery-Backup Circuits Reset Generator 165 mA·h = 2.5 years User’s Manual 111 112 Index SMODE0 SMODE1 ADCALALL.C User’s Manual 115 116 Schematics