Redundant, priority-based, robust gear shifter

A pushbutton electronic circuit, comprising:

• first, second, third and fourth pushbuttons, prioritized from highest to lowest, each having a normally open pair of terminals that are closable and a normally closed pair of terminals that are openable;
• a first, resistor-based analog circuit connecting a first one of the normally open pair of terminals of each of the pushbuttons to a first output terminal to output distinct analog voltages for presses of each of the pushbuttons and to ignore a lower priority pushbutton press that is simultaneous with a higher priority pushbutton press;
• and
• a second, resistor-based analog circuit connecting a first one of the normally closed pair of terminals of each of the pushbuttons to second and third output terminals to output distinct combinations of analog voltages for presses of one, two, three or all four of the pushbuttons to identify each possibility.

A pushbutton electronic gear shifter circuit, comprising:

• first, second, third and fourth pushbuttons, each having a normally open pair of terminals that are momentarily closable and a normally closed pair of terminals that are momentarily openable;
• a first, resistor-based analog circuit connecting a first one of the normally open pair of terminals of each of the pushbuttons to a first output terminal to output:
• a first voltage responsive to each of the first pushbutton being pressed alone and the first pushbutton being pressed with one, two, and three others of the pushbuttons;
• a second voltage responsive to each of the second pushbutton being pressed alone and the second pushbutton being pressed with the third, the fourth, and the third and the fourth of the pushbuttons but not the first pushbutton;
• a third voltage responsive to each of the third pushbutton being pressed alone and the third pushbutton being pressed with the fourth pushbutton but not the first pushbutton and not the second pushbutton;
• and
• a fourth voltage responsive to the fourth pushbutton being pressed alone;
• and
• a second, resistor-based analog circuit connecting a first one of the normally closed pair of terminals of each of the pushbuttons to second and third output terminals to output distinct pairs of voltages responsive to conditions of button presses comprising the first pushbutton alone, the second pushbutton alone, the third pushbutton alone, the fourth pushbutton alone, the first and second pushbuttons, the first and third pushbuttons, the first and fourth pushbuttons, the second and third pushbuttons, the second and fourth pushbuttons, the third and fourth pushbuttons, the first, second and third pushbuttons, the first, second and fourth pushbuttons, the first, third and fourth pushbuttons, the second, third and fourth pushbuttons, the first, second, third and fourth pushbuttons, and no pushbuttons pressed.

A method of operating a resistor-based analog circuit having four pushbuttons, comprising:

• producing distinct analog voltages at a first output terminal to identify presses of each of the pushbuttons;
• producing a same distinct analog voltage at the first output terminal for presses of a combination of one or more lower priority pushbuttons and a higher priority pushbutton as for an individual press of the higher priority pushbutton;
• and
• producing distinct combinations of analog voltages at second and third output terminals to identify all possible presses of one, two, three or all four of the pushbuttons.