The PIC12C will then emulate the keyboard , sending the appropriate sequence , last digit. Since this conversion. SpinWarrior is a family of rotary encoder controllers , products. Abstract: rotary encoder mouse Text: industrial input device and peripheral market since The keyboard controller fam ily "KeyW arrior", combined keyboard and mouse controller fam ily "KeyW arrior Com bo", and mouse controller family , which are switch selectable to work as a mouse or joystick allowing cursor control or data input via a , labs, control switches and displays in front panels or simulator cockpits, or work as the U SB interface in many kinds o f products.
SpinWarrior is a family o f rotary encoder controllers with U SB. Various models allow from 3 to 6. Abstract: circuit diagram of fm transmitter how to code rf transmitter RF encoder used in transmitter ds how keyboard encoder work DS rf code using PIC c how to code rf transmitter using PIC remote control encoder MHz Text: datasheet.
Supplied in rugged alminium IP65 rated enclosure, the encoder is complete and ready to operate. Operation of the Tx encoder buttons will cause either a momentary or a latching action. It produces a 2-bit rotational life of 1 million cycles , , must be provided. The square package is compact and well suited EM14 14 mm optical encoder is , ergonomic feel of a standard contacting The EM14 Series encoder converts rotary input encoder with the reliability and long life of a into electrical signals, which can be used by non-contacting encoder.
KeyWarrior and KeyWarriorM support a 8x8 key matrix. KeyWarrior is preprogrammed with general keyboard layouts. KeyWarriorS3 supports nine direct connected. A typical design includes either a circuit board or a flimsy material hereafter simply flimsy that lies underneath the buttons on the keyboard. Laid out on the flimsy is a maze of circuits. Directly beneath each keyboard button on the flimsy are two halves of a circuit.
The underside of the button has a conductive material of some kind. When the button is pressed, the conductive material comes into contact with the two halves of the circuit below, completing the circuit. Variations on this design exist, but almost all are similar. Take a look at Figure for an example. How the keyboard operates should sound very familiar. The only piece that the keyboard has that is missing in the arcade pushbutton circuit is the keyboard encoder.
Could we use the encoder from a real keyboard for our purposes? Take a look at the keyboard encoders shown in Figure Notice the connectors at the edge of the keyboard encoder boards. Those stripes are the contacts that the circuits on the flimsy come back to. Referring to FIG. A keypad is typically a small version of a keyboard, typically having 16 to 32 keys, and usually having fewer keys than the 84 to or more keys found on computer keyboards.
In a typical keypad application, the system 50 includes a keypad 52, a keypad encoder 54, a microcontroller 56 or other electronic circuit that receives digitized information from the keypad encoder 54, and a controlled system The keypad encoder 54 is a device that scans the keypad, determines which, if any, keys are depressed, and outputs a digital value that identifies the depressed key.
The controlled system 60 may be a transmitter, a machine on a factory floor, an automated teller machine, or any other electronic equipment utilizing a keypad for user control. In many such applications, the entire system is powered by a battery 62, and thus it is important to minimize energy usage by the entire system 50, and in particular it is important to minimize energy usage while the system is dormant i.
In the prior art, the keypad encoder 54 consumes power even while a system 50 is dormant because it continuously scans the keypad for depressed keys. Those keypad encoders continuously scan a keypad for depressed keys. The present invention is similar in many respects to the aforementioned keypad encoders.
However, in the present invention the keypad is'scanned only when a key is depressed. Power is saved by A disabling the oscillator that drives the keypad's scanning circuitry except when a key has been pressed, and B disabling the keypad scanning circuitry except for a very short period of time when a key has been pressed.
The disabling of the scanning circuitry is the primary manner in which power is saved. Another aspect of the present invention is that the scanning circuit is adapted to enable all the keypad columns simultaneously when the circuit is in the dormant mode so as to enable detection of any key press without having to scan the keypad.
An enable and reset circuit, coupled to encoder logic, detects new key presses, enables the oscillator and scanning circuits, and turns off the oscillator and scanning circuits after the depressed key has been identified and its identity has been latched in an output latch. Yet another aspect of the present invention is that the keypad encoder's "scan on demand" circuitry is adapted to allow scanning and encoding of "rolling" key presses, in which a second key is pressed before a previously pressed key is released.
While this is not a problem for a continuous scanning encoder, a feature of the present invention is that the scanning of the keypad will be automatically resumed if a second key is pressed before the previously pressed key is released. In summary, the present invention is a keypad encoder used with a keypad having an array of keys arranged in columns and rows. Depressing any key on the keypad closes a corresponding switch and couples one of the columns to one of the rows.
An oscillator generates a clock signal. An encoder circuit, coupled to the rows of the keypad, generates a first signal identifying which of the rows, if any, has a closed switch in any of the keypad columns on which the scanning circuit has asserted the scanning signal. After a depressed key is sensed, the control signal is put in the first state, causing the scanning circuit to scan the keypad until the row associated with the depressed key is identified by the encoder circuit.
The depressed key's column and row identification is stored in an output circuit, and the control signal is put in the second state after the depressed key is released. The scanning circuit stops scanning the keypad once the depressed key is identified by the encoder circuit and the scanning circuit's scanning operation is disabled when the control signal is in the second state.
Additional objects and features of the invention will be more readily apparent from the following detailed description and appended claims when taken in conjunction with the drawings, in which:. Since the present invention uses much of the same circuitry as the MM74C keypad encoder made by National Semiconductor, that circuit will be described first, and then the differences between that continuous scanning keypad encoder and the present invention will be described. For simplicity, we have selected a keypad encoder for a small key keypad as an example of prior art continuous scanning keypad encoders.
The prior art keypad encoder 54 includes an oscillator circuit 70 and a keypad scanning circuit The oscillator circuit 70 is a typical simple oscillator circuit whose frequency is controlled by a capacitor C OSC that is external to the integrated circuit in which the keypad encoder is implemented. The oscillator circuit 70 generates a periodic clock signal CLK that typically has a frequency of less than 10 KHz, and usually has a frequency of to Hz.
The keypad scanning circuit 72 includes a counter 74, and a decoder and column driver circuit The counter 74 in this example is a simple two stage counter that counts from 0 to 3 in increments of 1, and then repeats that sequence.
The counter 74 outputs a two bit signal representing the counter's current count value. The NAND gates 76AD preferably have open-drain outputs that can pull their respective output nodes to a logic low voltage level typically 0 volts, often designated as Vss but cannot pull up the voltage of their respective output nodes. Because each of the NAND gates 76AD is coupled to a unique combination of the counter output signals, only one of the driver circuit gates is activated at any one time, and thus only one column of the keypad switches is scanned for depressed keys at any one time.
In particular, with each cycle of the CLK signal from the oscillator 70, the counter 76 increments its output value by one. The purpose and generation of the keydown and debounced keydown signals are explained below. The four rows 82AD of switches in the keypad array are coupled to four current sources Y0-Y3 that cause the row connectors to be at a logic high voltage level e. Thus, whenever no keys are depressed, the counter 74 changes output values at a fixed rate, such as times per second assuming a clock rate of Hz , and thus a next one of the column driver NAND gates is activated and a new one of the keypad columns is activated times per second.
As a result, all the columns of the keypad are scanned times per second. Whenever a key is depressed, the switch under the depressed key is closed and the corresponding row line 82AD will transition to a low logic level voltage the next time that the column corresponding to the depressed key is activated by the counter Next, we consider the operation of the encoder circuit 90 and the debounce circuit The encoder circuit 90 includes four sensor circuits 93AD, each of which includes going from left to right in FIG.
Each of these four sensor circuits outputs a low signal on a respective one of nodes 98AD when the row input to the sensor is active i. In this document, "negative logic signals" which are signals that are at a low logic voltage level when active are indicated by a signal name with a backslash at the end.
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