©Quantum Research Group Ltd.
high, the key will still recover by means of the drift
compensation process, albeit more slowly.
5.4 Setup Commands
Setup functions are those that alter the behavior a key or a
group of keys. The setups are programmed into eeprom
locations in the part and ordinarily do not need to be
reprogrammed once set. However it is possible to change a
setup while the device is in normal operation without
interrupting the sensing function of the part.24
^C 0
X
03 - NEGATIVE
T
HRESHOLD
H
Bytes / Cmd Byte 2 Range
YSTERESIS
Scope
16
16
Returns
0x03
0x01..0x03
Put
Get
2
1
0x01..0x03
n/a
Section 2.3, p. 5
Setup functions alter the internal eeprom, and this requires a
much longer time to complete than other commands; see
Table 4-1.
Ctrl-C. In Put mode, the command followed by a setting is
programmed into eeprom for all keys only. The value should
be from 0 to 3, representing hysteresis as follows:
Setup 'put' commands become effective immediately after the
echo response of the command byte unless otherwise noted;
some setups require that the key(s) being altered be
recalibrated with the 'b' command (page 24) before they take
effect.
0: 50%
1: 25%
2: 12.5%
3: 0% (no hysteresis)
Values other than the above will be rounded down.
^A 0
X
01 - NEGATIVE
D
ETECT
T
Bytes / Cmd Byte 2 Range
HRESHOLD
The percentage is the distance from the threshold level to the
reference level. The hysteresis level is always closer to the
threshold point than to the reference point. 25% is a
reasonable value under most conditions.
Scope
1, 4, 16
1
Returns
0x01
0x04..0x40
Put
Get
2
1
0x04..0x40
n/a
Section 2.1, p. 5
As this parameter is common to all keys, Put and Get
operations send or return only one byte.
Ctrl-A. In Put mode, the command followed by a setting is
programmed into eeprom for the key(s) affected by scope.
^D 0
X
04 - POSITIVE
T
HRESHOLD
H
Bytes / Cmd Byte 2 Range
YSTERESIS
1, 4, or 16 keys may be affected. Valid decimal values are:
Scope
16
16
Returns
0x04
0x01..0x03
4
5
6
17 20 25 30 35 45 55 64
7
8
10 12 15
Put
Get
2
1
0x01..0x03
n/a
Values other than the above will be rounded down.
Section 2.3, p. 5
In Get mode, the command will return a single byte according
to the current scope rules (Section 5.2).
Ctrl-D. Identical in operation to ^C above except this applies
to positive 'detections' used to recalibrate the sensor (see ^B
above for details). Uses same hysteresis values as ^C above.
This controls key sensitivity by setting the counts of signal
delta needed to cause a detect. Higher = less sensitive.
Numbers should be 6 or greater under most conditions to
reduce the probability of noise detection. Numbers greater
than 20 indicate that the burst length is probably too high.
This setup interacts with Burst Length (^F).
^F 0
X
06 - BURST
Scope
1, 4, 16
1
L
ENGTH
Bytes / Cmd Byte 2 Range
Returns
0x06
0x00..0x40
Put
Get
2
1
0x00..0x40
n/a
^B 0
X
02 - POSITIVE
D
ETECT
T
Bytes / Cmd Byte 2 Range
HRESHOLD
Section 3.5, p. 8
Scope
1, 4, 16
1
Returns
0x02
0x04..0x40
Ctrl-F. In Put mode the command sets the burst length of one
or more keys, according to the current scope. Valid decimal
values are:
Put
Get
2
1
0x04..0x40
n/a
Section 2.2, p. 5
0
1
2
3
4
5
12 15 20 25 30 40 50 64
7
10
Ctrl-B. In Put mode, the command followed by a setting is
programmed into eeprom for the key(s) affected by scope. 1,
4, or 16 keys may be affected. Valid decimal values are:
Values other than the above will be rounded down.
In Get mode, the command will return a single byte according
to the current scope rules (Section 5.2).
4
5
6
7
17 20 25 30 35 45 55 64
8
10 12 15
^F sets the length of the acquisition burst on a key by key
basis. This setting is directly proportional to signal gain. This
setup interacts with Negative and Positive Threshold (^A and
^B). Increasing ^F can allow for higher threshold levels and
more robust signals, at the expense of increased radiated
emissions and reduced Cx load capacity.
Values other than the above will be rounded down.
In Get mode, the command will return a single byte according
to the current scope rules (Section 5.2).
This setup controls the ability of a key to recalibrate quickly
should the signal transition positive quickly, as when a touch
is prolonged enough to cause a recalibration, and when the
key is then 'untouched'. This condition can also be caused by
a foreign object being removed from a key. The value should
normally be set between 6 and 10 counts. If the value is very
Special condition: If the value for ^F for a key is set to zero
the burst disabled and the key will not function; the key will
report back with an error code. The timing for the 'phantom
burst' will be preserved so that overall key scan timing will
remain unchanged.
lQ
21
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