Glass TouchKeypad and IchigoJam part2

A Glass Touch Keypad and IchigoJam Trial 2

IchigoJam と　ガラス　タッチキーパッド　I2C接続

 



Key pads are formed with Aluminum fine pattern
Lower resistance than ITO

Continuous work after Dec10 2015 post

 

This time, the glass touch keypad worked.

Touch controller : Atmel AT42QT2120

 

Set up - put a printed sheet underneath the glass keypad.

 

 

 

 

 

 

 

 

 

 

1. Wiring(5)

I2C connection to the IchigoJam

 SDA--->IN3

 SCL---->EX1

 

 /Change---IN1        (Watch status change) normally "H"

I2C Address  0x1C   (Fixed)
 

VCC--3.3V

GND--GND

2. Initialize of AT42QT2120(Atmel sensor driver chip)

Reset  "/Change "   L to H      (Normally H but L at turn-on)

First thing to do;
Reset the chip!   This was a bit tricky.

 

Send reset command   0x07,0xFF(any nonzero value)

wait 500msec. (250msec Min?)

Dummy status read from the chip (I did this but not shown in the spec)

3. Read Keydata

Check  any key detection status change "/Change"

  Wait /Change  H->L

or

  Read sensor detection status (0x02)

 

Read data command   0x03

   data  D7,D6,----D0

Read data command  0x04

   data  x,x,x,x,D11,D10,D9,D8

 

Note;

I saw no key data even when "/Change" became L.

I just ignored null data.
 

4. Convert data to Key number

The order of  leadout from the glass keypad is not

the same as sensor chip input/output numbering.

I had to convert the sensor data by the following

order.

 

Glass keypad 1,2, 3, 4, 5,6, 7,8,9,10,11,12

sensor data    1,0,11,10,2,4,7,9,3, 5, 6, 8

Multi-touch can be read.
 

 5. Other settings

This Atmel chip can be set in various sensing mode.

For the pratical use it might be needed.

6. Trial kit

This kit is not  being sold, but free samples are available both in the US and Japan(Tech Support)
I'll provide some samples for the educational /leaarning purposes.



7. Atmel AT42QT2120



AT42QT2120 PCB for Glass touch keypad

Comm Mode : 1 to 12 keys, 1-9 wheel or slider

Standalone Mode:1 to 5 keys

 



Reference of pin numbers and Key number