This board is used for
production testing of a dental gas flowmeter. It is connected to the
flowmeter using a ribbon cable and adapter module that plugs into the
flowmeter in lieu of the flowmeter's keypad. The text fixture is a
programmable device which simulates any desired sequence of keypresses.
The LCD screen uses a menu-driven interface to permit the operator to
enter programs, test them, change the delay between keypresses, and the
number of times the program is run. While the program is running, the
LCD display shows the number of cycles, and a white LED by each button
lights whenever the test fixture is "pressing" that button. The fixture
can run 10 or 20 flowmeters simultaneously using a daisy-chained ribbon
cable.
Gory details: The heart of the test fixture is a PIC microcontroller. A separate serial EEPROM device stores the program and user settings. They keypad and the eight buttons to its right and left are scanned as a 4x5 matrix, much like a computer keyboard. The LCD is 20 characters wide by four rows. Power is brought in from a simple 9V DC adapter through the plug to the upper left and regulated onboard. The yellow potentiometer along the top edge allows adjustment of the LCD contrast.
This board is a "midrange" level project.
Gory details: The heart of the test fixture is a PIC microcontroller. A separate serial EEPROM device stores the program and user settings. They keypad and the eight buttons to its right and left are scanned as a 4x5 matrix, much like a computer keyboard. The LCD is 20 characters wide by four rows. Power is brought in from a simple 9V DC adapter through the plug to the upper left and regulated onboard. The yellow potentiometer along the top edge allows adjustment of the LCD contrast.
This board is a "midrange" level project.