Uc1701

UC1701

Copyright(c) 2018 BitBank Software, Inc.<br> <br>

UC1701 is a simple C library for working with the 128x64 mononchrome LCD display when connected to the SPI bus. The idea is to provide a simple interface for C programmers to make use of those low-cost LCD displays without having to read the data sheet or figure out SPI programming. Unfortunately the display controller needs a couple of control lines (GPIO pins) for Reset, backlight and Data/Command; this requires extra work. In this case, I use my ArmbianIO library (https://github.com/bitbank2/ArmbianIO) <br> To build the library, simply type 'make' in the terminal. To build the sample app, type 'make -f make_sample'. This will build the demo executable to show that the library is working. Press ENTER to exit the demo. <br> Troubleshooting tips:<br> <b4>

1. Make sure to enable the SPI interface and check the bus number (e.g. /dev/spidev0.0)<br>
2. Connect the "CS" pin of the UC1701 to the CE0 pin on the header.<br>
3. You can use any GPIO pins to control the D/C,RST/LED lines; initialize the library with the pin numbers used (not GPIO numbers)<br>

The connection names can be confusing, here's the 'translation':<br>

Arduino/RPI           JLX12864
-----------           --------
<any GPIO pin>        LEDA (controls backlight, can be driving from a GPIO pin)
GND                   VSS
Vcc (3V)              VDD
MOSI                  SDA
SCLK                  SCK
<any GPIO>            RST (reset)
<any GPIO>            RS (labeled D/C in my code)
<any GPIO>            CS

<br> Power Consumption:<br> ------------------<br> This LCD controller is advertised as being extremely low power. It is, but the PCB I received had several power issues that I had to manually solve. There is a 3.3V and 5V version of the PCB (usually JLX12864G). The 5V version includes a 3.3v linear regulator. The regulator doesn't stop it from working when given 3.3V, but it does waste a little energy. My board started out at 2.25mA (@3.3v) when active and 2.0mA when sleeping. This is quite a bit different from the current draw claimed in the UC1701 datasheet. I removed the linear regulator, but that only reduced the current a small amount. I then discovered that my PCB included a Chinese character font EPROM (U1). This chip when idle was drawing nearly 2mA! I removed it and now the LCD draws nearly 0 when idle and 276uA when active. The backlight (with included 120 ohm resistor) draws about 4.8mA. A good improvement over the Nokia 5110 (400uA active current).<br>

Written by Larry Bank<br> Project started 2/22/2018<br> bitbank@pobox.com<br> <br> If you find this code useful, please consider buying me a cup of coffee<br>