PCI-104 and PC104p Compatible

BaseBoard shown mounted to rear mounting plate.

The BaseBoard is part of the PC/104 Module family of modular I/O components by Dynamic Engineering. The BaseBoard is used to integrate a PCI-104 or PC/104p stack with the power supply, 35 Optocoupled Inputs, 37 Optocoupled Outputs, 2 UART - RS-485 ports, 2 ARINC 429 - TX/RX, 4 ADC Ports, and 4 DAC Ports comprize the onboard feature set of the BaseBoard design. The Right hand PC104 slot is designed to be occupied by the Power Supply module which accepts 28V and supplies the standard PC104 voltages on the ISA connector. The left hand slot in the figure above is used to add a PCI-104 or PC/104p stack. The stack will include the system CPU. The BaseBoard occupies slot position 0.

BaseBoard Block Diagram

Optical Isolated input circuit

The input signal when high will turn on the LED of the optocoupler and drive the received bit to the Xilinx. The optocouplers are all in this basic arrangement but with some variations for the reference input voltage to match the type of input being measured. The receiver inverts the data as it operates as an open-drain device. The Xilinx inverts the input bits to compensate. When the LED is turned on the status bit for the unfiltered data will be "1".

Within the Xilinx the data is sampled at a programmable rate. The input bits are arranged in "words". Each word has a separate programmable clock. Each bit has a separate control register to program the filter to look for active high, active low, Change of state etc. The circuits are designed to operate in a noisy environment and use hysteresis to help. The filter has a programmable threshold for a low and high value. The values are compared with an up-down counter to determine if the bit should be declared to be a "1" or a "0". The counter acts as accumulator. The hysteresis comes from staying in the "0" state until the counter is into the "1" state and vice-versa.

Optical Isolated output circuit

The Optocoupled outputs are controlled with registers within the Xilinx. The outputs are organized as "words". When the bit is set the open drain IO is driven low to turn on the optocoupler. With the LED turned on the opto isolated FET is turned on and the output connected. Some of the switches are configured to be high side and some low side. Some have fuse protection and some have resistor coupling depending on the requirements of the external circuit.

The ARINC 429 interface is made up of two sets of ARINC 429 compatible interface chips. Each set has a controller with a pair of built in receivers and a separate transmitter buffer. One receiver and one transmitter are connected from each chip set to connectors. The Xilinx is tied to both receiver channels.

The PCI bus is 32 bits and the ARINC devices are 16. The PCI bus is much faster than the local bus to the ARINC chips. The Xilinx takes care of converting 32 bit TX data to 16 bit writes and the timing required to load the devices. The ready bit can be used to determine when the next data can be written. When data is available to read from the device the Xilinx retrieves it and stores it before telling the CPU that data is ready to allow the CPU to retrieve the data in one read without added delays accessing the ARINC devices.

There are 4 A/D and 4 D/A provided. Each of the devices is 16 bits and 200 Khz rated for operation. The devices are separately interfaced to allow individual or parallel operation depending on the requirements. Each A/D and D/A has power filtering in the form of a filter bead and added capacitors for improved performance. The Analog channels have a voltage divider capability [resistor positions] designed into the BaseBoard to allow for out of range voltage measurements.

The Xilinx provides two UART circuits. The UARTs operate in half-duplex mode and have programmable baud, parity, and stop bit capabilities. A pair of RS-485 transceivers convert between the single ended Xilinx signals and the differential external IO standard. The channels are programmed to come up as receivers and can become transmitters under software control. The two channels could be combined to make one full-duplex channel should that be required.

The PC/104p-BaseBoard is designed to be rugged. The board layout features high current 2 oz copper and heavy tracewidths for the opto-coupled IO. The MDM connectors are designed to operate under vibration loading. The Baseboard has a low power dissipation and can be conductively cooled or convection used. An internal isolated shield plane is exposed at the board edges for mounting to the chassis for cooling and electrical purposes. The parts are rated for industrial operation or better [-40 - +85C]. The PC/104p-BaseBoard comes humisealed and can be used in condensing environments.

PC/104p-Baseboard Features

  • Size
  • Custom board size. Standard PC/104p or PCI-104 sites. Outline drawing available upon request

  • IO Speeds
  • Dual Speed ARINC 429, up to 200 Khz [ADC and DAC], up to 1 MHz on the UART ports.

  • Clocks
  • Programmable clocks for OptoIsolated inputs, UART, ARINC ports

  • PCI
  • 32/33 operation is supported for the PC/104p or PCI-104 stack.

  • Software Interface
  • Read-write ports to control interfaces

  • Interrupts
  • Software programmable interrupts on all active circuits plus status to operate in polled mode.

  • Ports
  • 35 Optocoupled Inputs, 37 Optocoupled Outputs, 2 UART - RS-485 ports, 2 ARINC 429 - TX/RX, 4 ADC Ports, and 4 DAC Ports

  • Power
  • Slot provided to add PC/104 ISA routed power supply card. Local regulation for 3.3, 2.5, and 1.25V. Power routed to PCI-104 / PC104p connectors to support the stack. High current internal planes utilized.

    Engineering Kits
    Dynamic Engineering provides Engineering Kits to help our customers have a successful and quick integration. Engineering Kits will save time and money with decreased T&I. We recognize that different customers have different needs. The Engineering Kits are standardized in description to help with selection. The kits are segmented to allow for customers who only need hardware support, software support or a mixture. The Engineering Kit is highly recommended for first time buyers. The kit pricing is discounted to encourage their use.

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    PC104p-BaseBoard Hardware manual for PC/104p-BaseBoard. Rev A3 Nov 1, 2006

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