|Contents||The I2C-2-PC adaptor makes it easy to quickly design
new equipment or retrofit computer control to test
equipment and specialised control electronics.
Here are examples of real equipment.
If you would like us to design an interface for you, or just give you some suggestions, contact us
This is a custom made part of a Phase Noise test system. It contains relays, filters, amplifiers, and so on. It works with other of-the-shelf eqipment, and custom software to form a high volume production test system.
Its a typical example of the kind of box that has to be custom made to connect all the other "ready-to-use" equipment together into a real functioning manufacturing system.
Since its a one off we don't want to be writing firmware for micro's, or designing complex computer interface cards. The function is simple: We need to be able to turn things on and off, and read some diagnostic voltages back to the PC.
For ease of use it has front panel switches to manually control everything.
We use 2 PCF8574 8 bit I/O ports to control the relays and amplfiers. As they are bi-directional, open drain units, we can use front panel switches, and read them back from the PC.
To check the diagnostic voltages we use a Philips 8591 4 channel A-D convertor. We don't need much accuracy, we are looking for defective cables, dead amplifiers etc.
The generator we use has front panel knobs, but we can add an LCD and shaft encoder IC when we want.
PTS manufacture economical frequency synthesisers. Unfortunately the available interface is a BCD interface. The bcd interface posed a number of problems:
We wanted an RS232 interface for these generators.
The generator needs about 40 control lines. They need to be bi-directional to either remote control the instrument, or read back the front panel setting to a PC.
In addition the output level needs an A-D to monitor the actual value, and a D-A for setting it remotely.
We use 5x PCF8574 for the parallel I/O, and a single PCF8591 for both the A-D and D-A convertors.
Because the circuit is so simple it took less than 1 hour to design. As the track layout is so simple with the I2C bus, the whole board was autorouted on the first pass.
If we want to add a digital display to generators without the manual controls, we can just plug in an existing I2C-LCD adaptor.
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