I am embarassed to waste your time with probably obvious question, but I am having trouble finding keypads with gadgeteer compatibility.
So far I can only find normal keypads from other websites like this 4x4 (16 key) matrix keypad with 8 pinouts 16 Key 4x4 Alpha Numeric Keypad or other 4x4 common-point keypads which use a seperate pinout for each key and sometimes an extra 2 pinouts (so 16 to 18 pinouts).
For the 4x4 matrix keypad I assume it needs to be connected to 8 seperate GPIO pins on the Cobra II board.
Will this be easy to wire up and program for (I heard that sometimes matrix keypads are a pain to program for) or should I go for a common-point 4x4 keypad and use up extra GPIO pins?
Also the description says, current rating 20mA at 24V DC, but the GPIO pins are rated at 3.3V.
Will this still work if I run it off the Cobra II board?
The Cobra II has a total of 72 GPIO pins with 7 GPIO pins in each of the two Y sockets and 3 GPIO pins in each of the three X sockets (so far 23 GPIO) but where are the rest located? According to the Cobra II schematic I cannot see any expansion headers labelled as GPIO (but I see two labelled as I2C).
I want to use a 20x4 LCD Text Display like this one I2C 20x4(2004) LCD Display for Arduno - DFRobot
with the 4x4 Keypad. (I prefer 4 lines of text display instead of only 2 lines sold by ghielectronics because it can show more on screen at once).
But the 20x4 LCD has two I sockets which make a problem because Cobra II only has one I letter plug and one set of I2C pins on the expansion header (equivalent to one I letter plug).
Does anyone have advice on how to connect the two I sockets directly to the Cobra II board by using the breakout modules and some wiring?
What would be the best way to use both a 20x4 LCD and 4x4 keypad on the Cobra II?
I think most efficient would be to use something like HD44780 Module (now discontinued) to convert standard 20x4 LCD pinouts to a single Gadgeteer Y socket output (which would then be easy to connect and program for same as 16x2 Gadgeteer LCD).
For this can someone please give me instructions for how to make my own HD44780 Module (now discontinued) using breakout modules and resistors/transistors?
I tried to understand the schematic for it but the resistor DNP (do not place), resistor 0 ohms, ‘pick one’, and ‘which type of transistor to use’ are confusing for me.
Any help or suggestions welcome, and thank you