Method and apparatus for detecting key actuations

A method of detecting key actuations in an electronic device, the electronic device including a first plurality of keys, a second plurality of keys, and a processor, the processor having a plurality of inputs including a plurality of row inputs and a plurality of column inputs, the method comprising the steps of:

• (a) biasing the plurality of inputs at a first predetermined voltage during a first predetermined time period and at a second predetermined voltage during a second predetermined time period;
• (b) detecting, during the first predetermined time period and in response to a coupling of a unique combination of one row input of the plurality of row inputs and one column input of the plurality of column inputs to the second predetermined voltage, an actuation of one key of the first plurality of keys;
• and
• (c) detecting, during the second predetermined time period and in response to a coupling of a unique combination of one row input of the plurality of row inputs and one column input of the plurality of column inputs to the first predetermined voltage, an actuation of one key of the second plurality of keys.

A method of detecting key actuations in an electronic device, said electronic device having a processor including at least one input, said method comprising the steps of:

• (a) biasing the at least one input at a first predetermined voltage during a first predetermined time period and at a second predetermined voltage during a second predetermined time period;
• (b) generating, during the first predetermined time period and in response to a coupling of the at least one input to the second predetermined voltage through at least a first resistor, a third predetermined voltage having a value different from the first predetermined voltage;
• (c) generating, during the second predetermined time period and in response to a coupling of the at least one input to the first predetermined voltage through at least a second resistor, a fourth predetermined voltage at the at least one input, a fourth predetermined voltage having a value different from the second predetermined voltage;
• (d) detecting the third predetermined voltage at the at least one input during the first predetermined time period;
• and
• (e) detecting the fourth predetermined voltage at the at least one input during the second predetermined time period.

A method of detecting key actuations in an electronic device, the electronic device including a processor and a plurality of keys, the processor having a plurality of inputs and an output, the output coupled to and biasing the plurality of inputs, the plurality of keys including a first plurality of keys and a second plurality of keys, the method comprising the steps of:

• (a) setting the output to a first predetermined voltage during a first predetermined time period, thereby biasing the plurality of inputs at the first predetermined voltage during the first predetermined time period;
• (b) toggling, in response to an actuation of each key of the first plurality of keys, a unique combination of the plurality of inputs to a second predetermined voltage during the first predetermined time period;
• (c) reading the plurality of inputs during the first predetermined time period;
• (d) comparing the plurality of inputs and a set of predetermined key patterns during the first predetermined time period;
• (e) detecting, in response to a match between the plurality of inputs and one key pattern of the set of predetermined key patterns, an actuation of one key of the first plurality of keys during the first predetermined time period;
• (f) setting the output at the second predetermined voltage during a second predetermined time period, thereby biasing the plurality of inputs at the second predetermined voltage during the second predetermined time period;
• (g) toggling, in response to an actuation of each key of the second plurality of keys, a unique combination of the plurality of inputs to the first predetermined voltage during the second predetermined time period;
• (h) reading the plurality of inputs during the second predetermined time period;
• (i) comparing the plurality of inputs and the set of predetermined key patterns during the second predetermined time period;
• and
• (j) detecting, in response to a match between the plurality of inputs and one key pattern of the set of predetermined key patterns, an actuation of one key of the second plurality of keys during the second predetermined time period.

An apparatus for detecting key actuations, the apparatus comprising:

• a printed circuit board (PCB), said PCB including a first plurality of contact regions and a second plurality of contact regions, each contact region of said first plurality of contact regions including a first conductive pad, a second conductive pad, and a third conductive pad, each contact region of said second plurality of contact regions including a fourth conductive pad, a fifth conductive pad, and a sixth conductive pad, each said first conductive pad coupled to a first predetermined voltage through a first resistor, each said third conductive pad coupled to a second predetermined voltage through a second resistor;
• a keypad, said keypad including a first plurality of keys and a second plurality of keys, each key of said first plurality of keys corresponding to one contact region of said first plurality of contact regions, each key of said second plurality of keys corresponding to one contact region of said second plurality of contact regions;
• and
• a processor, said processor including a plurality of inputs and an output, each said second conductive pad and each said third conductive pad coupled to a unique combination of two inputs of said plurality of inputs, each fifth conductive pad and each sixth conductive pad coupled to a unique combination of two inputs of said plurality of inputs, said output coupled to each input of said plurality of inputs through a plurality of resistors, said processor biasing said output at the first predetermined voltage for detecting actuations of said second plurality of keys and at the second predetermined voltage for detecting actuations of said first plurality of keys.

An electronic device comprising:

• a printed circuit board (PCB), said PCB including:
• a first plurality of contact regions, each contact region of said first plurality of contact regions including a first conductive pad, a second conductive pad, and a third conductive pad, each said first conductive pad coupled to a first predetermined voltage;
• a second plurality of contact regions, each contact region of said second plurality of contact regions including a fourth conductive pad, a fifth conductive pad, and a sixth conductive pad, each said fourth conductive pad coupled to a second predetermined voltage;
• a keypad disposed adjacent to said PCB, said keypad including:
• a first plurality of keys, each key of said first plurality of keys corresponding to one contact region of said first plurality of contact regions and electrically coupling corresponding said first, second, and third conductive pads when actuated;
• a second plurality of keys, each key of said second plurality of keys corresponding to one contact region of said second plurality of contact regions and electrically coupling corresponding said fourth, fifth, and sixth conductive pads when actuated;
• and
• a processor, said processor including a plurality of inputs and an output, each said second conductive pad and each said third conductive pad being coupled to a unique combination of two inputs of said plurality of inputs, each said fifth conductive pad and each said sixth conductive pad being coupled to the unique combination of two inputs of said plurality of inputs, said plurality of inputs being coupled to and voltage biased by said output, said processor setting said output to the first predetermined voltage for reading and detecting actuations of said second plurality of keys, said processor setting said output to the second predetermined voltage for reading and detecting actuations of said first plurality of keys.