HANDLING PC/104 PERIPHERALS – ENTERING THE EMBEDDED AND INDUSTRIAL COMPUTERS WORLD
1. Traditional handling of PC/104 peripherals
One traditional PC/104 computer system consists of one CPU (microprocessor) module , and one or more peripheral cards.
Hardware of a PC/104 computer system Architecture of a PC/104 system
In the architecture of a PC/104 system, on hardware level there are number of PC/104 cards , including one microprocessor card , and one or more peripheral cards . On the software level there is normally an embedded operating system, and service software - device drivers and/or applications.
One PC/104 system may be stand-alone system, or it may be connected in a network of other PC/104 and/or desktop / notebook computer systems.
2. New way of handling PC/104 peripherals
The PC/104 bus is identical as signals to the ISA bus, with the difference in the mechanical implementation - fixed size of the circuit board and use of a particular connector.
We have designed a PC/104 to ISA adapter capable of connecting both - PC/104 cards with ISA cards. General information and images of the adapter are available at - ISA-PC104.
Some of the features of the ISA-PC104 - PC/104 to ISA adapter include -
- The ISA side of the adapter is capable of connecting with USB2ISA-SLOT- USB to ISA slot version card, as well as one or more 8 bit or 16 bit ISA cards;
- The PC/104 side of the adapter is capable of connecting with one or more 8 bit or 16bit PC/104 peripheral cards.
- Able to provide +5V power supply to the PC/104 peripherals; capable of taking the isa-pwr POWER SUPPLY MODULE for having additional voltages of -5V , +12V and -12V.
A minimum hardware configuration for servicing of a PC/104 peripheral include - one PC/104 peripheral card, one ISA-PC104- PC/104 to ISA adapter , and one USB2ISA-SLOT - USB to ISA slot version card .
The configuration is powered on through the USB cable, connected to USB host computer system. If the PC/104 peripheral needs the additional voltages of -5V , +12V and -12V the isa-pwr - POWER SUPPLY MODULEcan be mounted on the isa-pc104 - PC/104 to ISA adapter .
Warning1: Please do not connect PC/104 CPU/microprocessor card together with isa-pc104 adapter and usbisa-sl card.
Warning2: If using multiple isa-pc104 adapters, please mount only one isa-pwr - POWER SUPPLY MODULE.
The above configuration replaces the direct control of a PC/104 CPU card under an Embedded OS, with control from a host computer under general OS , through USB .
On the software side, the service software of the PC/104 peripheral card - a driver and/or an application has to be converted to work through USB, and transferred to the Host computer. We are offering a software kit - SDKBUS, with samples to help the conversion.
Note1: PC/104 cards are generally based on the low power CMOS technology, and can be powered on through the USB cable. Please measure the currents consumed from the PC/104 peripheral and make sure they do not exceed the 500mA/+5V available by the USB specification.
Note2: Some of the PC/104 peripherals perform time critical functions. Please evaluate the performance of the new configuration through USB, to make sure all the tasks are performed well.
3. Configurations
3.1. Stacking PC104 cards, adding ISA cards
The ISA-PC104 adapter allows stacking - mounting PC/104 cards on the top and on the bottom of ISA-PC104 adapter -
If the PC/104 stack has a CPU card then 1 ISA card may be mounted in the isa connector of ISA-PC104 adapter. Or, the stack of PC/104 cards with ISA-PC104 adapter can be plugged in a passive ISA backplane -
3.2.Handling PC104 cards and ISA cards with USB2ISA
The ISA-PC104 adapter allows stacking of PC/104 peripheral cards on the top and on the bottom of ISA-PC104 adapter - The PC/104 stack in this case does not include a CPU card.
But ISA-PC104 adapter can be used together with one of the USB2ISA family of cards.
The USB2ISA-SL card can be plugged in the ISA connector of ISA-PC104 adapter
Or, ISA-PC104 adapter can be plugged in - USB2ISA-R, USB2ISA-X3, or USB2ISA-X7 cards -
In additions to the configurations described there are many other possible configurations.
One example of a configuration contains - 2 PC/104 peripheral card, two ISA-PC104 - PC/104 to ISA adapters, one usb2isa-sl - USB to ISA slot version card and one ISA card . Each additional ISA card needs an isa-pc104 adapter. The appendix of this article includes pictures - please refer to it for the way of stacking multiple PC/104 and ISA cards.
The USB Host computer can serve currently up to 8 cards of the USBISA family. The number of served cards may be increased in the future.
The figure bellow offers a way of converting of 2 PC/104 computer systems into a configuration which services the PC/104 peripherals, through USB , from an USB Host computer system .
If the peripherals in the figure need additional voltages, the new configurations may include isa-pwr - POWER SUPPLY MODULE.
The above configuration will need conversion of the software related to the 3 PC/104 peripherals, to work through USB, on the Host computer. The functioning of each of the PC/104 peripherals needs to be evaluated, to make sure they perform within the assigned parameters.
Appendix : Pictures of the PC/104 to ISA adapter and configurations based on it - - Top view of the PC/104 to ISA adapter
- Side view of PC/104 to ISA adapter
- Unassembled minimum configuration
- Assembled minimum configuration
- Mounting a standard ISA card
- Mixed configuration with a PC/104 peripheral, and an ISA
- Stacking PC/104 and ISA cards