Make your own free website on Tripod.com

Operating Instructions

 

Simply plug the synthesizer in and turn the power switch on. After one second, the unit will say "READY" indicating that it is ready to accept commands.

Operating Sequence

Refer to the keypad configuration. The following is intended as definitions and examples for operating the synthesizer/filter.

 

SET Sets the square wave synthesizer and analog filter to a specified frequency.
Press "SET"
Press "6"
Press "8"
Press "0"
Press "0"
Press "EN(ter)"

Square waves of 6800 Hz now appear at the square wave output.

CAL Starts the adaptive calibration routine. The 68HC11 looks at the bandpass of the filter for each frequency stored in EEPROM and adjusts the coefficients in EEPROM for any drift, etc., in component values in the analog filter.
Press "CAL"
Press "EN(ter)"
LEVEL-2 Changes the definition of all keys on the keypad. Level 2 is for altering the stored startup configuration in EEPROM
Press "L2" (GO TO LEVEL 2)
Press "STORE FREQUENCY IN EEPROM"
Press "RECORD IN EEPROM AND ENTER"

The last frequency entered is stored in EEPROM. On power-up, the synthesizer and filter are set to this frequency.

CLEAR Clears the last entry. Used to cancel a mistaken keyboard entry. The clear button is used as an alternative to the enter button.
Press "SET"
Press "9"
Press "CL(ear)"

Clear cancels the previous 2 entries.

ENTER Enters a command.
Press "L2" (LEVEL 2)
Press "12 VOLT PULSES"
Press "EN(ter)"

The square wave amplitude is now 12 volts.

RECORD IN EEPROM AND ENTER Enters a command and stores value in EEPROM for power-up.
Press "L2" (LEVEL 2)
Press "12 VOLT PULSES"
Press "RECORD IN EEPROM AND ENTER"

The square wave amplitude is not 12 volts. On power-up, the square wave amplitude will default to12 volts.

12 VOLT PULSES Sets the square wave amplitude to 12 volts. See previous example.
5 VOLT PULSES Sets the square wave amplitude to 5 volts.
Press "L2" (LEVEL 2)
Press "5 VOLT PULSES"
Press "RECORD IN EEPROM AND ENTER"

Also stores this value in EEPROM for power-up default.

CONNECT BANDPASS FILTER TO SYNTHESIZER Filter is placed in high Q lowpass mode and connected internally to synthesizer output.
Press "L2" (LEVEL2)
Press "CONNECT BANDPASS FILTER TO SYNTHESIZER"
Press "RECORD IN EEPROM AND ENTER"

Filter is connected internally to synthesizer output. Sine wave appears at filter output. Filter defaults to this mode on power-up.

SELECT HIGH PASS FILTER, EXTERNAL INPUT Filter is placed in two pole Butterworth mode. Highpass cutoff frequency of the filter is the same as the synthesizer frequency. The input of the filter is connected to the BNC labeled "FILTER INPUT"
Press "L2" (LEVEL 2)
Press "SELECT HIGH PASS FILTER, EXTERNAL MODE"
Press "EN(ter)"

Filter is place in highpass mode. Filter will not default to this mode on power-up since "RECORD IN EEPROM AND ENTER" was not selected.

SELECT BANDPASS FILTER, EXTERNAL INPUT Filter is placed in high Q bandpass mode.
Press "L2" (LEVEL 2)
Press "SELECT BANDPASS FILTER, EXTERNAL INPUT"
Press "EN(ter)"
SELECT LOWPASS FILTER, EXTERNAL INPUT Filter is place in 2 pole Butterworth lowpass mode.
Press "L2" (LEVEL 2)
Press "SELECT LOWPASS FILTER, EXTERNAL INPUT"
Press "EN(ter)"
FILTER GAIN 0 dB Filter is set to unity gain. In connect mode, the filter output is approximately 10 volts peak-to-peak.
Press "L2" (LEVEL 2)
Press "FITLER GAIN 0 dB"
Press "RECORD IN EEPROM AND ENTER"

Filter is set to unity gain. This will be the default condition for power-up.

FILTER GAIN -20 dB Filter is set to a gain of 0.1. In connect mode, the filter output is approximately 1 volt peak-to-peak.
Press "L2" (LEVEL 2)
Press "FILTER GAIN -20 dB"
Press "EN(ter)"

"EN(ter)" does not cause the filter gain to be stored in EEPROM for power-up.

FILTER GAIN -40 dB Filter is set to a gain of 0.01. In connect mode, the filter output is approximately 0.1 volt peak-to-peak.
Press "L2" (LEVEL 2)
Press "FILTER GAIN -40 dB"
Press "EN(ter)"

Examples:

1. Turn the power on. After one second the unit will say "READY"
2. Push "SET", (unit will beep)
Push "5", (unit will beep)
Push "0", (unit will beep)
Push "1", (unit will beep)
Push "EN" (unit will say "FIVE HUNDRED ONE HERTZ")

The square wave synthesizer and the analog filter will be set to 501 Hz.

3. Push "L2" (Unit will say "LEVEL TWO")
Push "5 VOLT PULSES"
Push "RECORD AND ENTER"

Square wave output will be set for TTL level pulses. The TTL output level will now be the default condition at power-up.

4. Push "L2" (Unit will say "LEVEL TWO")
Push "HERTZ"
Push "RECORD AND ENTER"

On power-up, the default frequency for both the square wave synthesizer and the analog filter will be 501 Hz.

5. Push "L2" (Unit will say "LEVEL TWO")
Push "CONNECT"
Push "ENTER"

The filter input will be connected to the 501 Hz square wave. The filter will be placed in a high-Q bandpass mode. The filter output will be a 501 Hz sine wave. Since "RECORD AND ENTER" was not pushed, this filter configuration will not be recalled on power-up unless it had previously been stored.

6. Push "L2" (Unit will say "LEVEL TWO")
Push "0 dB"
Push "RECORD AND ENTER"

The filter output will be approximately 10 volts peak-to-peak at 501 Hz.

7. Push "CAL" (unit will say "CALIBRATE")
Push "EN" (unit will say "ENTER")

The filter is a voltage controlled filter. The lookup table for these voltages is stored in EEPROM. The "CAL" button causes the program to adapt the values stored in EEPROM for any changes or misalignments in the center frequency of the filter. This is done by placing the filter in its high-Q bandpass mode. The square wave synthesizer is used to provide the filter with an input. The output of the filter is rectified, filtered, and sampled by the A/D converter when the input compare enables it. The value of the voltage stored in EEPROM is changed such that the amplitude of the filter output is maximized. By watching the square wave and the sine wave outputs simultaneously on a dual trace oscilloscope, the adaptive calibration may be observed. Later we will change some of the components in the filter circuit so that we can watch the adaptive algoritym reprogram the lookup voltages in EEPROM to compensate for the component changes.

8. Push "FC" (unit will measure and announce the frequency of the signal into the counter input)
9. Push "L2" (unit will say "LEVEL TWO")
Push "IND" (unit will beep, measure, and announce the inductance of the inductor connected to the IND terminals.)
10. Push "L2" (unit will say "LEVEL TWO")
Push "CAP" (unit will beep, measure, and announce the capacitance of the capacitor connected to the CAP terminals.)
11. Push "L2" (unit will say "LEVEL TWO")
Push "PROG" (unit will ask for access code)
Push "123" (unit will ask for starting address in memory)
Push "B630" (unit will say what is in memory at that location)
Push "Next" (unit will say what is in memory at B631)
Push "EN"
Push "01" (unit will write 01 into memory location B631)
Push "Clear" (unit will return to the main level)

Return to 68HC11 Start Page