ACCESS-TOUCH HEXWAX, ACCESS-TOUCH Datasheet - Page 2

• Manufacturer Part Number: ACCESS-TOUCH
• Description: IC, TOUCH KEY CONTROLLER, SSOP-20
• Manufacturer: HEXWAX

Specifications of ACCESS-TOUCH

• Ic Interface Type: Serial
• Supply Voltage Range: 2V To 5.5V
• Sensor Case Style: SSOP
• No. Of Pins: 20
• Operating Temperature Range: -40°C To +85°C
• Interface Type: Serial
• Package / Case: 20-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device Pinout
Bill of Materials
The Table 2 shows the recommended components for
the bill of materials.
components for providing power or driving the lock
release, which will be application specific.
sizes apply to the gerber files in the product blueprint.
How It Works
The touch pads measure the capacitance of the
interleaved touch contacts using a relaxation oscillation
p2 of 4
ClosedLED ‘Closed’ LED output
Rst# / Vpp Reset input, active low / Vpp programming input
OpenLED
Click 1, 2
TouchC
TouchD
SetLED
TouchA
TouchB
Touch0
Touch1
Touch2
Touch3
LED1-3
R8-R10
SetSw
Name
Lock#
R4-R7
Label
Lock
PGD
Vdd
Vss
R11
R12
C1
C2
C3
R1
R2
R3
U1
X1
J1
Table 3. Suggested component values
Description
Buzzer driver
Lock release, active high
Lock release, active low
‘Open’ LED output
PGD programming input
‘Set Code’ LED output
Set Code input control, active high
Touch sensor input 0 (Keys 1, 2, 4, 5)
PGC programming input
Touch sensor input 1 (Keys 0, 2, 3, 6)
Touch sensor input 2 (Keys 0, 4, 7, 8)
Touch sensor input 3 (Keys 5, 6, 8, 9)
Relaxation Oscillator Drive Output
Relaxation Oscillator Reference Voltage Drive
Relaxation Oscillator Reference Voltage Input
Relaxation Oscillator Counter Input
2.0V – 5.5V supply
Power supply ground
470R resistor 0402, adjust for LED brightness
PIC16F631-SS with AccessTouch preloaded
10k resistor 0402, adjust for buzzer volume
Light emitting diodes, e.g. HSMx-C265
Jumper or switch for ‘set code’ control
Table 2. Pinout Table
7-Sep-08
Piezo buzzer, e.g. CMT-1603
100nF capacitor 0402
The table does not include
1uF capacitor 0402
1nF capacitor 0402
120k resistor 0402
22k resistor 0402
3k3 resistor 0402
10k resistor 0402
1k resistor 0402
Component
Access-Touch
Package
oscillator which scans the contacts in turn.
finger is placed close to the contacts, the capacitance
will increase, reducing the frequency of the oscillator. A
sudden drop in capacitance is interpreted as a button
press.
The touch pads measure changes in capacitance
relative to a recent moving average.
some resilience to changes in humidity and water
splashes. In order to achieve reliable operation, keys do
not need to be pressed hard, but they must be held for
approximately 250ms.
When power is applied, all three LEDs light for
approximately
capacitance is initially measured.
After a period of inactivity, an optional sleep state
reduces the key scan rate to once every 500ms. If this
mode of operation is used, the first key must be held for
this time in order to wake the device.
Vss, Vdd
Vss is the power supply ground reference. Vdd should
be connected to a DC supply of 2.0V – 5.5V.
TouchA – Touch D
The TouchA to TouchD pins configure the relaxation
oscillator and should be connected as shown in figure 1.
Touch1 – Touch4
The Touch1 to Touch4 pins are capacitance sense
inputs. They should be connected to the touch pads as
shown in figure 1.
Vpp, PGC, PCD
TEAclipper programming pins.
and Programming section for details. Note that the Vpp
pin may be subject to voltages as high as 12V during
programming.
RST#
The pin is an active low reset input. It is important that
this is connected to a 22k pull-up to Vdd, the TEAclipper
connector, and nothing else.
Open LED
Outputs high when the lock release is triggered. This
pin can drive up to 25mA.
Closed LED
Outputs high when the lock release is not triggered and
the device is not in a sleep state. This pin can drive up
to 25mA.
Set Code LED
Outputs high when the SetSw input is high. This pin can
drive up to 25mA.
SetSw
Set Code input control. Set to Vdd to enter a new code.
The code must be entered twice and is acknowledged
with a beep. This minimizes the chance of entering in
an incorrect code while keeping user operation simple.
It does mean, however, that codes made up of repetitive
HW140-1
15
seconds
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