Keypads typically require a lot of pins from the microcontroller to operate, but this board interfaces to keypads with the two pin I²C interface. This project consists of a board that sits on the back of the keypad, and provides two Grove type I²C connectors for easy connection to a microcontroller. This board also has the I²C pullup resistors (enabled with solder jumpers) and jumpers to select the I²C address. The board will operate on either 3.3 or 5 volts.
The keypads need to be a “matrix” style keypad, where there is one pin for each row and one pin for each column of keys. For example, a keypad with 4 rows of keys and three columns of keys will have 7 pins on it. When a key is pressed, it produces a shorted connection between the row and column pins. This backpack board will work with keypads that have a maximum of 8 pins (and 16 keys is the maximum supported size, 4×4).
A0, A1, and A2 control the I²C address of the board. all open = 27h,all closed = 20h.
Contact resistance of 500 ()
Insulation resistance 100M ()
Key Operating Force 150-200N
Rebound time 1 (ms)
Life of 100 million (times)
Operating Temperature 60 ()
1, the electronic characteristics
Circuit Rating: 35V (DC), 100mA, 1W
Contact resistance: 10 ~ 500
(Varies according to the lead lengths and different from those of the material used)
Insulation resistance: 100M 100V
Dielectric Strength: 250VRms (50 ~ 60Hz 1min)
Electric shock jitter: <5ms
Life span: tactile type: one million times
2, the mechanical properties
Operating pressure: Touch feeling: 170 ~ 397g (6 ~ 14oz)
Switch travel: touch-type: 0.6 ~ 1.5mm
3, the environment parameters
Operating temperature: -40 to +80
Storage temperature: -40 to +80
Temperature: from 40,90% to 95%, 240 hours
Vibration: 20G, max. (10 ~~ 200Hz, the Mil-SLD-202 M204.Condition B)
Package:
1 x (4 x 4) Matrix Array 16 Key Membrane Switch Keypad Keyboard
2 x Cables
1 x I2C Keypad Backpack Board