Note: This version has been replaced with the newer version 3.2.

RS-232 / I²C & Parallel I/O Adapter Module

RS-232: This module is used to control external components via the I²C bus using simple command sequences sent and received via an RS-232 port from an application running on a PC (sample Visual Basic application with source code is included), PDA, or other platform. The on-board MAX-232 level shifter insures there will be no signal level problems and allows for maximum cable length.

I²C Bus Master: The RS-232 / I²C-Adapter acts as an I²C master, and can perform the most frequently used read/write operations via the bus without the need for the application software to handle the I²C protocol. When the application sends one of the "macro command sequences", the adapter takes care of generating the start condition, transmitting the address plus the R/W bit, transmitting/receiving data bytes plus setting/reading the acknowledge bit, and finally generating the stop condition. All of this is transparent to the application software.

I²C low-level: To ensure compatibility, the adapter also allows the application software to directly "talk" to the I²C bus in order to allow communications with I²C devices that require non-standard sequences, using "low-level commands".

I²C Monitor: In its Monitor mode, the module acts as an I²C "spy", i.e. it passively monitors an I²C bus, and sends the byte data transferred via the bus together with the information, if there was an acknowledge, or not via RS-232. An internal 32-byte FIFO buffer, together with an 115.2 kBaud RS-232 rate allows for I²C bus rates of up to 100 kBit/s to be monitored.

Relay Output: In addition, the RS-232 / I²C-Adapter comes with a reed relay which can be controlled by dedicated commands. This allows the application software to initialize various devices via the I²C bus before finally turning on the power supply for other components, for example. Besides this, the relay may also be used as a general-purpose isolated output.

General Purpose I/O: There are also four non-isolated outputs, and eight non-isolated inputs that can be set/read by specific adapter commands. The inputs also clock eight individual 16-bit counters that may be read/reset by designated adapter commands.

Reliable WDT: As an additional option, a timer may be activated that resets the I²C-Adapter when new commands are not received within the specified time-out period.

Status Indicators: Thee LEDs are used to indicate the status of the RS-232/I²C-Adapter, the activities on the I²C bus, and the RS-232 lines.

The RS-232/I²C-Adapter is based upon a Ubicom/Parallax SX-28 microcontroller, clocked at 50 MHz. Single, pre-programmed chips are available for customers who want to integrate the RS-232/I²C-Adapter's functionality into their own hardware design (see below).

Specifications:

• Power Supply requirement: 5V DC, stabilized and filtered
• Relay Output: 1A, 250v DC (maximum ratings)
• Parallel Outputs: 4, TTL (0/5V), 30 mA sink/source
• Parallel Inputs: 8 TTL (0/5V), Schmitt-Trigger characteristics.
• RS-232 I/O: 115.2 kBaud, 8N1 (handshake is handled by the command protocol)
• I²C: 100kbit/s transfer rate (can be set to 20, 50, or 100 kbit/s)
• Dimensions: 2" x 2" (50mm * 50mm)
• Connectors: Two male 14-pin headers, 0.1" (2.54mm) spacing

Available Modules:

• Replaced by new versoin 3.2 $15 RS-232/I²C-Adapter Chip: Includes the pre-programmed SX controller.
• Replaced by new versoin 3.2 $23 RS-232/I²C-Adapter Main Parts Kit: Includes PCB, SX controller, and a 50 MHz resonator.
• Replaced by new versoin 3.2 $40 RS-232/I²C-Adapter All Parts Kit: Includes PCB, and all components.
• Replaced by new versoin 3.2 $50 RS-232/I²C-Adapter A&T: Assembled and tested.

All modules are shipped with a CD-ROM containing the documentation, schematics, assembly instructions, and the sample VB application project.

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OPTIONAL EXTENSION

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Relay/Iso/Analog I/O Module w/ Power Conversion

This is a companion board for the RS-232/I²C-Adapter which can piggy-back via two 14-pin header sockets.

DB-9 Connector: An on-board standard SUB-D 9 connector is provided to directly connect the RS-232/I²C-Adapter's serial port to a COM port.

Isolated Inputs: It also contains eight PC849 opto-isolators to convert the RS-232/I²C-Adapter's input lines into isolated inputs.

Relay Outputs: Four reed relays are included to isolated the 4 TTL outputs from the RS-232/I²C-Adapter. The RS-232/I²C-Adapter relay output is fed-through to two separate connectors.

Analog I/O: In addition, the board comes with a Philips PCF8591 chip which extends the I/O capabilities of the RS-232/I²C-Adapter to four 8-bit analog inputs, and one 8-bit analog output.

Power : An on-board DC/DC converter enables this module to accept any DC supply voltage from 8V to 38 V, un-regulated. The DC/DC converter output is available to supply other components that are connected to the Parallel/Analog I/O Board.

Specifications:

• Acceptable Power Supply Range: 8…38 V DC, unregulated.
• Power out: 5V regulated @ 500mA, fused with over-voltage protection.
• Relay Outputs: 4 more (5 w/RS-232/I2C Adapter), 1A, 250vDC (maximum ratings)
• Digital Inputs: 8, Opto-isolated, 5…30v, common minus.
• A/D inputs: 4, 0…5v, 8bit resolution, single-ended or differential inputs.
• D/A output: 0…5v, 8bit resolution (no resistive load)
• Dimensions: 4" x 3.2" (100mm * 80mm)
• Connectors: Clamp plugs, 0.15" (3.81mm) spacing

Available Modules:

• Replaced by new versoin 3.2 $110 Relay/Iso/Analog Parallel I/O & PS A&T: Assembled and tested, including matching clamp plugs.
• Replaced by new versoin 3.2   $20 Relay/Iso/Analog Parallel I/O & PS Bare Board: PCB only; populate just what you need.

All modules are shipped with a CD-ROM containing the documentation, schematics, and assembly instructions.

Available Module sets: save money!

• Replaced by new versoin 3.2 $150 RS-232/I²C-Adapter Assembled and tested
  with Relay/Iso/Analog Parallel I/O & PS option Assembled and tested
• Replaced by new versoin 3.2   $65 RS-232/I²C-Adapter Assembled and tested
  with Relay/Iso/Analog Parallel I/O & PS option PCB only

Comments:

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