123
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
10
SECTION 10 - KEYPAD
The keypad contains touch-sensitive keys that allow the
operator to interface with the OptiView Control Cen-
ter. The operator presses the keys to request the desired
screens of information and enter System Setpoints.
The top layer of the keypad contains embossed areas
identifying the keys. Under each embossed key area
are two conductors, one on top of the other, separated
by an air space. The conductors are arranged in a ma-
trix of rows and columns and connected to the keypad
connector as shown in
embossed area of each key is located directly over the
intersection point of the conductors. Pressing the em-
bossed key area causes contact and electrical continu-
ity between the two conductors. For example, press-
ing the “1” key creates continuity between the keypad
connector pin 5 (column 3) and pin 13 (row 4). Since
this connector is interfaced to the microboard (J18), the
microboard senses this continuity as described below
and concludes the “1” key is pressed.
The microboard Program continuously scans the key-
pad to determine if a key is pressed. Beginning with
row 1 and proceeding through all rows, the Program
places a “logic low” (less than 1 VDC) on a row, a
“logic high” (more than 4 VDC) on the remaining rows
and reads the columns. A logic low in any column in-
dicates a key in that column and row is pressed. For
example, if at the time row 4 is being driven low, if
column 3 is low, then the microprocessor concludes the
key at coordinate of row 4 and column 3 is pressed.
Since the coordinates of all keys are stored in the mi-
croboard’s Program, it can identify which key is at this
coordinate and responds accordingly. In this example
the “1” key is pressed.
In order for the microboard to reliably detect closed
and open keys, each key must meet a closed circuit
and open circuit resistance requirement. When a key
is pressed, the contact resistance must be less than 100
Ohms. When a key is not pressed, the contact resis-
tance must be more than 1Meg Ohm. If the microboard
is not responding to a pressed key, or if it’s detecting
a closed key when none are pressed, it could be be-
cause the contact resistance requirements are not being
met. The operation of each key can be checked with an
Ohmmeter. To check the open and closed contact resis-
tance of any key, see
of this manual.
The keypad is attached to the front of the OptiView
Control Center door with an adhesive backing. If ser-
vice replacement is required, start at one corner and
slowly peel the keypad from the door. The rear side
of the replacement Keypad is coated with an adhesive
covered with a paper backing. Remove the paper back-
ing, align the Display and rocker switch openings and
apply the keypad to the door.