Running a USB Simulation
In practice, running a USB simulation differs little from any other VSM simulation. The typical procedure is outlined below.
- Install the USB Drivers – these are supplied as standard with your Proteus installation and will only work with 32-bit Windows computers/virtual machines.
- Design the schematic in ISIS for the USB Peripheral device you want to make. Remember to place and wire the USB connector schematic part on the schematic.
- Take the firmware framework for the USB device class you are implementing and modify the top level to be application specific. Manufacturers typically supply free firmware that will handle the low level communications – for example, the Microchip Technologies PIC18 USB code can be downloaded here.
- Apply the COF/HEX file to the program property of the microcontroller schematic part in ISIS.
- Run the simulation via the PLAY button at the bottom of the ISIS application.
- Click on the USB Connector schematic part to connect the USB device – this is equivalent to plugging in the physical equivalent device to your PC.
- Use the USB Transaction Analyser to monitor and verify USB traffic as your simulation progresses.
- Debug and test your firmware and circuit as per any normal Proteus VSM simulation – bearing in mind that the USB Protocol has a 30 second timout limitation (your simulation needs to respond to requests within 30 seconds).
- Stop the simulation via the STOP button at the bottom of the ISIS application.
- Modify firmware or ‘hardware’ as required and re-run the simulation to test.
- When complete use the netlist command to transfer to ARES and commence PCB Layout.
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