Stan: FT232-based USB LCD backpack
|Stan: FT232-based USB LCD backpack|
I have been experimenting with the FT232R as a USB to SPI interface. Some of it is on the web at www.chinwah-engineering.com.
After looking at the BP LCD interface I got to thinking that driving the LCD directly with FT232R is a bad idea and that using the '595 simplifies the software immensely. And so it follows that it would be possible to build a backpack for a LCD to run off of the USB bus. Sort of like the Olimex PIC-MT-USB but without the PIC. Should be a lot cheaper.
- Backpack (80x36)
- Simple/Low cost
- Dumb requires host for programming
- Support for the most common 1x8, 1x16, 2x8, 2x16 ... up to 4x40 character dispalys and some graphic displays
- Support for 3v3 and 5v
- FT232R breakout (all pins)
- Limit the total USB current to 500mA.
- jumpers to swap Vcc and Gnd at the JP3 and JP4
The standard board size for a basic 16x2 character LCD display is 80x36 mm and has the 1x16 connector in the top left front. There are four mounting holes. There are a lot of variation in the sizes and connectors. Some even have the 1x16 connector at the bottom left but the pinout is 14-1,16,15 left to right. Some displays have the 2x8 connector but pins 1 and 2 have reversed voltage polarity. I think we should stay with what we have discussed and with a board size of 80x36.
595 timing table
2x8 HD44780 pinout
Here we will list the LCDs we have tested with the LCD backpacks successfully and explain how to connect them if they can't be plugged into the backpack directly. We encourage users to add LCDs they have tested successfully with the USB LCD backpacks to this list.
A. LCD character displays (HD44780 compatible)
|8*2||LMB0820DFC||TOPWAY||8*2 character, white/blue||KS0066||connects to 2x8 header JP3|| Seeed Studio
|16*2||DEM16217 SYH-PY||Display Elektonik GmbH||16*2 character, STN yellow/green||ST7066U-0A-B|| connects to 1x16/24 header JP4,
pin 1-14 LCD --> pin 1-14 backpack, pin L+, L- LCD --> pin 15 (+BL), 16 (GND) backpack
|16*2||WH1602B-TMI-JT#040||WINSTAR||16*2 characters, white/blue||S6A0069||connects to 1x16/24 header JP4||Sure Electronics (DE-LM201)|
|20*4||LMB204BCF||TOPWAY||20*4, white/blue, white LED backlight||KS0073||connects to 1x16/24 header JP4|| Seeed Studio
|20*4||JHD204A 040319 REV 1.0||JHD (?)||20*4, yellow/green, yellow LED backlight, cheap generic LCD||unknown||connects to 1x16/24 header JP4||eBay|
B. LCD graphic displays
Manufacturing test plan
- Connect a HD44780 LCD to the backpack as shown
- Place a jumper on JP1 to select the backlight ground (usually GND to GND), the inner two pins
- Place a jumper on JP2 to select the LCD power supply, usually 5.0V
- Plug in the USB cable
- Start the LCD application
- Choose the display size from the Display drop-down menu
- Select backlight->on to turn on the backlight
- Type some text in the box and click Enter Line 1 to display it on the LCD
If the backlight is enabled, and the text displays, then the board should be fully functional.