ACCESS-TOUCH-EVAL HEXWAX, ACCESS-TOUCH-EVAL Datasheet - Page 3

• Manufacturer Part Number: ACCESS-TOUCH-EVAL
• Description: Capacitive Touch KeyPad Demo Board
• Manufacturer: HEXWAX

Specifications of ACCESS-TOUCH-EVAL

• Silicon Manufacturer: Hexwax
• Application Sub Type: Touch Sensor
• Kit Application Type: Sensing - Touch / Proximity
• Silicon Core Number: PIC16F631
• Kit Contents: Board And Literature
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

sequences longer than the minimum code length cannot
be specified, e.g. 12341234.
Typically the set switch will only be accessible from
inside the secured-access area, or will be implemented
as a key switch.
The code set by default is 123.
Lock, Lock#
The lock outputs control the access lock. These pins
can drive up to 25mA, sufficient for a small relay.
Click1, Click2
Connect to a buzzer to provide audio feedback:
These pins can drive up to 25mA, so a current limiting
series resistor may be required. This is the function of
R12 in figure 1, which also serves as a volume control.
Touch Pad Design
The touch pads need to be designed for maximum
capacitance when a finger is present, and minimum
capacitance when not present. The design shown in
figure 1 has been shown to be effective, with a track
width of 1.1mm and gap of 0.33mm. The overall pad
size should be at least 13mm square, with a minimum
gap between pads of 5mm.
No physical contact is required and the touch pads may
be overlaid with, for example, a label or thin acrylic
panel. Alternatively, the pad may be placed in an inner
PCB layer immediately below the exposed PCB surface.
Button presses are detected as a rise in capacitance in
one or two sense lines. Too high a trigger sensitivity
can be just as troublesome as low a trigger sensitivity.
Therefore the sensitivity setting may require adjustment
to suit a particular physical setup.
settings section below.)
To avoid ambiguity, it is important that fingers do not
induce
unnecessary routing tracks on the exposed surface of
the PCB. Apart from the touch pads, the circuit should
avoid being placed where fingers might get close. Avoid
metal enclosures.
Non-Volatile Settings
Various settings can be specified in the code memory at
programming time (see the Programming AccessTouch
section). Alternatively, they may be set in EEPROM
memory at a later date using a PIC programmer. The
EEPROM locations are shown in table 4.
p3 of 4
Address
0x00
0x01
0x02
0x03
High note:
Medium note: Code set
Low note:
Table 4. Nonvolatile Settings In EEPROM
capacitance
OpBeep
OpTime
UseEE
Name
Sens
7-Sep-08
Default
Button press registered
Lock open
0x00
0x38
0x08
0x01
where
Zero to use code memory
settings, or non-zero for
EEPROM settings
Touch trigger sensitivity
Lock open time, 1/3s units
Zero for no beep on unlock
not
Description
wanted.
(See nonvolatile
Access-Touch
Avoid
Note that the access code is also stored in EEROM and
is visible to anybody with a PIC programmer.
Firmware Delivery on HexWax
If
AccessTouch
encrypted
www.hexwax.com. To download it you will need a
TEAclipper/PIC HV and a TEAclipper/USB adapter.
To load the firmware onto the TEAclipper, start the
HexWax Explorer firmware and log in.
download the AccessTouch firmware pack from
the
download completes, an AccessTouch folder will
appear in the Local Files section of HexWax
Explorer. In this folder is the AccessTouch.wax
file that contains the firmware.
You will need AccessTouch license credits in order
to decrypt the AccessTouch.wax file.
hexwax.com for details of payment options and
how to obtain free samples.
Once you have license credits, select the
AccessTouch.wax file and insert a TEAclipper/PIC
HV into the TEAclipper/USB adapter. Press the
Charge Now… button. Referring to figure 3, select
how many licenses you wish to load onto the
TEAclipper. Additionally, select the desired Non-
Volatile Settings written into code memory as
MinLen-WaitSlp-OpBeep-OpTime-Sens (refer to
table 4).
enter 0300010838. Finally press OK to obtain a
decryption key and to charge the TEAclipper with
the decrypted firmware.
Address
0x04
0x05
not
HW140-1
hexwax.com
Figure 3: Decrypting the AccessTouch.wax file
Table 4. Nonvolatile Settings In EEPROM
WaitSlp
bought
MinLen
Name
For example, for the default settings,
firmware
firmware
Default
0x00
0x03
as
products
a
Wait time before entering
sleep mode, or zero for no
sleep, 1/15s units
Minimum number of digits
permitted in a new code.
pre-programmed
is
www.firmwarefactory.com
download
available
section.
Description
Contact
as
When
Then
chip,
from
an