USB Keypad Demonstration

Report
Crystal Free USB with mTouch
Demonstration
www.microchip.com/USBkeypad
www.microchip.com/usb
Kit Contents
• USB Keypad w/ bumpers
• USB Keypad Block Diagram
• 3ft USB A to mini-B 5pin 28/28AWG Cable
• Lumvatech Company Profile Insert
Crystal Free USB Keypad with mTouch
Demonstration Highlights
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All features driven by single device –
PIC16F1459
Crystal free USB operation
18 touch buttons using Capacitive
Voltage Divider (CVD) technique
LED backlight with proximity sensing ON
and auto power OFF
USB HID interface
Plug and play
Low cost lightweight design
Audio feedback using the piezo buzzer
Development Made Easy
• Low-cost development experience
• Start with the FREE download
• Schematics & ‘C’ source code
• Easily modified to your specific application
needs
Download at www.microchip.com/USBkeypad
Crystal Free USB Keypad – Block Diagram
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PIC16F1459 device with USB, 9 Channel ADC, PWM, Active Clock Tuning, etc.
USB powered device
Current consumption < 100 mA
Matrix Key Design
COLOUMN 2
COLOUMN 0
COLOUMN 3
COLOUMN 1
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Key size
12mm*12mm
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ROW 0
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•
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S2
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S1
S3
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S4
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ROW 1
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•
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S6
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S5
S7
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S8
•
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ROW 2
•
•
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S10
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S9
S11
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S12
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ROW 3
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S13
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S14
S15
Guard
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ROW 4
S16
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S17
Guard ring 3mm away from
sensors. Thickness 1mm.
S18
Key size
12mm*31mm
Uses mTouch CVD
technique
9 ADC channels - 5
rows * 4 columns
Two columns are also
used as proximity
sensors
Guard ring to reduce
parasitic capacitance
on sensors
CVD application note
Lumvatech
Graphics, Panel, Keypad PCB
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Top panel with graphics
printed on it.
12 side firing LEDs (6
on each side) provide
backlighting.
Panels are provided by
Lumvatech.
(www.lumvatech.com)
High level Firmware
Architecture
Application
(keyboard.c)
(usb_function_hid.c)
mTouch
CVD
Stack
LED
and
Buzzer
Firmware Integrates
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HID
Function
Driver
USB
Device
Stack
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USB Device Stack
mTouch CVD stack
Both the stacks are part of
MLA
MLA is freely downloadable
at www.microchip.com/MLA
Simplified Application
Flow Chart
main()
Initialize USB,
mTouch()
A
ISR
Send 0x00 to
Host
No
No
Is USB Device in
Configured state?
Is any valid
mTouch key press
detected?
USBDeviceTasks();
Yes
Yes
mTouch_Scan();
No
No
Is proximity Sensor
press detected?
Is Last USB transfer
completed?
LEDService();
Yes
Yes
•Activate Keypad
•Turn ON LED backlight
Send corresponding
key to Host
End of
ISR
A
Buzzer Beep
Audio Feedback
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When Num Lock is ON, buzzer beep frequency is 1000hz
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When Num Lock is OFF, buzzer beep frequency is 2500hz
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Slightly longer beep for Num Lock ON and OFF
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Hold the Clear key for 2 Sec to turn ON/OFF the buzzer
feedback. Hold the key until a longer beep is heard from
the buzzer.
USB Keypad
Summary
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All features driven by single device – PIC16F1459
Active Clock Tuning for crystal Free USB
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Saves as much as $0.15 by eliminating external crystal
Guarantees 0.25% accuracy when connected to USB host
USB HID interface – plug and play
Capacitive touch sensing based on CVD technology
LED backlight with proximity sensing ON and auto power OFF
Sleek and low cost design
Easily modified to specific application needs
Download schematics & code at:
www.microchip.com/USBkeypad
Learn more…
Visit us on the web: www.microchip.com/USBkeypad
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Quick start guide
Application note and ‘C’ source code
Schematic and board files
Visit us on the web: www.microchip.com/USB
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USB Development Platforms
USB Reference Designs
USB Application Notes
USB Products & Peripherals
Partner Overview
A leading provider of microcontroller and analog semiconductors, providing lowrisk product development, lower total system cost and faster time to market. With
an increasing focus on lighting applications, Microchip offers outstanding
technical support along with dependable delivery and quality.
A leading U.S. based manufacturer of ultra-thin backlighting that provides
solutions from simple logo backlighting to complete user-interfaces. Lumvatech
serves the medical, white goods, brown goods, and automotive industries with
easy integration, fast speed to market, and high-quality lit products.

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