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Topic: HD44780 Boards using SPI Interface (Read 202 times) previous topic - next topic

casemod

Something everyone working with arduino should have...

I recently got enough of having wire a lot of wires to get an LCD working and designed some boards to drive them from SPI. The connections can simply be taken from the ICSP connector, so You'll never forget how to wire it.

I realize there are I2C Versions as well, but in my opinion these are more of a hassle than a solution, so I designed my own board using a SPI interface.

One neat feature I added (As I didnt seem to be able to find something with it) was the inclusion of a DC-DC converter. The arduino can be powered with anything from 2.7 to 5.5V - The board will scale the LCD voltage to 5V. I designed this primarily to be able to operate my arduino from a single lithium cell.

Here is a schematic:



Full Size

Attached below is the library and eagle schematics with the PCB (25*50mm) This is a drop in replacement of the standard parallel library that comes with the arduino, with many unneeded features removed to increase speed and reduce memory usage.

This installs just like any other library. Extract the folder to the libraries folder, restart the IDE and on the examples folder, there is an example with details of how to wire everything up (Schematic above also shows this)












CrossRoads

Pretty nice job. Double sided for parts installation.

What'd you use for some of the values on the parts that don't have values shown?
R2 - 500mR ?
L2
C1
C29
R44
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

#2
Mar 06, 2016, 06:50 pm Last Edit: Mar 06, 2016, 06:52 pm by CrossRoads
If you were to re-do it, I'd go with all parts on one side to eliminate the need for 2 solder stencils.

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

casemod

This is the BOM:

U1- MC34063 - SOIC8
U2 - 74HC595N
R1 - Potentiometer, 10K
R2 - 1R, 2510
R3 - 4k7, 0805
R4 - 1.5K, 0805
R5 - 180R, 0805
R44 - 120R (Limits the backlight current)
C1 - 16V/220uF, electrolytic 3.5mm pitch, 8mm OD
C2 - 15pF, 0805
C3, C4 - 2.2uF, 1206, XR7
C29 - 100nF, 0805
L2 - 10uH 2020 package, Farnell

The DC-DC was intended to supply the display only, it can cope with up to 30mA output, so the back light is limited trough R44.

The diode is a fast schottky diode on the DO241 Package. I'm using a ES1J but something like a 1N5819 would be preferred.







casemod

#4
Mar 06, 2016, 07:22 pm Last Edit: Mar 06, 2016, 07:24 pm by casemod
If you were to re-do it, I'd go with all parts on one side to eliminate the need for 2 solder stencils.


Might do, there's only 3 components under. I was thinking in replacing the shift register with the D variant (Narrow SOIC) and increase the inductor size, but was wondering whenever this might be a problem for others trying to assemble it. An alternative would be to place the large current sense resistor under the DIP shift register, its less than 1mm tall.

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