Hey there hopefully someone can point me in the right direction. I have a ‘SparkFun 16x2 SerLCD - RGB on Black’ and am not able to find clear documentation on the pins. The sparkfun site directs me to some general SerLCD hookup information, but the pin names do not match the ones I have and the documentation of this seems generally poor.
Can anyone help me fill in the blanks from what I have gleaned? Or correct me where I am wrong.
These are the pin locations as they appear on the back and labeled by what seems to be the groupings:
GRN FTDI BLK: Notes indicate these are used in Serial connections.
1: "-" Not referenced or used?
2: "-" Not referenced or used?
3: "+" Not referenced or used?
4: "RX" - This seems to be the only data PIN that Sparkfun references to use for UART connections, is this really the only pin needed? I assume this connects to a digital I/O pin? The only example is if you are using their controller to a specific pin. I can assume it is digital I/O, but documentation could be more clear.
5: "TX" Not referenced or used?
6: "R" Not referenced or used?
SPI - I recognize that this block of pins is just used for SPI so I can ignore them.
7: "SCK"
8: "SDO"
9: "SDI"
10: "/CS"
COM - Serial connections
11: "RX1" This is also an RX pin, but based on context I assume the other RX pin is the one referenced for connections.
12: "TX0"
I2C - I assume this is for a different type of connection and I can ignore them.
13: "CL"
14: "DA"
PWR - Power
15: "RAW" - These are the only other two pins referenced in the UART connection. (5v power)
16: "GND" - These are the only other two pins referenced in the UART connection. (Ground)
Also of note, in the tutorial (which is more general) the sample code references pin connections by other names, not how they are labeled on the LCD board. (Such as VIN for the 5v connection) :?
Let me know if I am missing something obvious. I am new to LCDs so maybe all of this makes sense to someone else and it is just me that is being obtuse. Is it really only three pins of the 16 that I will be using. I would like to know what the others are for if possible…
Edit: To complicate things further some images I see show the ‘RX’ pin referenced being the 2nd “RX1” (11) pin not the 1st one “RX” (4).
Check the [hardware overview section of the hookup guide for details on what the pins are for.
On the FTDI header, those pins match the functions on a FTDI cable and are only really needed if you are making changes to the firmware. If you’re not using a [FTDI, you really don’t need to worry about those pins at all.
Also, all the RX pins are the same, they are just duplicated to give flexibility in how you connect to the board. If you’re planning on only using serial, the 3 pin header labeled RX, GND, 3.3-9V is what I’d recommend using and leaving everything else alone.](https://www.sparkfun.com/products/9873)](https://learn.sparkfun.com/tutorials/avr-based-serial-enabled-lcds-hookup-guide/all#hardware-overview)
Much appreciated for your quick response, it confirms my understanding of only needing 3 pins, but the referenced hardware overview is the one I am referencing as being incomplete (or at least not thorough).
Feedback on that link:
Specific documentation regarding each pin is what I was hoping for. Many of your products have this, the 1’6X2 SERLCD - RGB ON BLACK’ does not. Some pins are never referenced in the guide and pins generally are not explained. The guide typically just says connect pin X to pin Y on your Arduino. Sometimes pins are referenced by different names with no context. (5v pin is also referred to as the VIN?) The guide lacks context and doesn’t tell me what the purpose of the pins are or what kind of pin it should be connected to. Sort of a teach a man to fish situation. Maybe I’m just hard headed, but I think the hardware guide for the SerLCD is lacking. I guess it is trying to be a basic tutorial for multiple products and glosses over the educational parts that I was hoping to obtain.
Not to knock you guys for this, but a nice technical hardware specific pdf on the product page would be welcome. 
In the hookup guide, the pictures show groupings of the pins based on protocols or functions. If you’re looking for more education, we reference different tutorials under suggested reading in the Introduction. These tutorials expand on how different protocols or topics work.
It would be near impossible to repeat this information unique for each product. So we link it in this way so you can read it before getting started. Please feel free to read these topics and other materials under our [Tutorials section.](https://learn.sparkfun.com/tutorials)
I am not asking for it to be in the space of the tutorial. Many of your products include datasheets, extended datasheets, and schematics in pdf form. The SerLCD does not. That is what I am looking for. There is precedent for this information as it is provided on many other products (including other LCD screens).
If you’re looking for information on the pins on the FTDI header, page 11 on this document shows the pin functions.
If you’re looking for information on serial (UART) we have a guide you might want to look at.
https://learn.sparkfun.com/tutorials/se … munication
We have a guide for I2C as well.
https://learn.sparkfun.com/tutorials/i2c
For the technical nitty gritty on I2C, see this link:
https://www.nxp.com/docs/en/user-guide/UM10204.pdf
We also have a guide for SPI.
https://learn.sparkfun.com/tutorials/se … erface-spi
For the technical data on SPI see:
https://en.wikipedia.org/wiki/Serial_Pe … _Interface
to complicate things further some images I see show the ‘RX’ pin referenced being the 2nd “RX1” (11) pin not the 1st one “RX” (4).
That’s RXi and TXo. (i = in, o = out) All the RX pins connect together and all the TX pins connect together. The i and o are just there to help you understand what direction data is flowing.
RST or R is ‘RESET’ and it’s not used by the end user.
Sadly we do not have a schematic for the SERLCD.