HiLetgo1602 LCD Keypad Shield 1602 LCD Expansion Shield Board Blue Backlight 4.5-5.5V for Arduino Duemilanove Robot

I've used these modules from different vendors. They so far all work reliably, including this one, but they all have one major flaw. The back light led is switched by a transistor. The circuit was obviously designed for a MOSFET but all vendors put a bipolar transistor there. There is a pull up from the base to supply, but no series resistor from board pin to the base. This means that a high on this output goes directly to the base of an NPN transistor, with the emitter connected to ground. That is pretty much a short circuit for that pin.There are two workarounds. Either never output a high on that pin. Only pull it low (backlight off) or put it in input mode (backlight on) or add your own transistor with series resistor in from of it. That is a pain as you need to cut the trace to the pin and solder a resistor to the trace. It would be best to add a resistor in series with the base on the board or mount a MOSFET but that resistor needs to be behind the existing pull up resistor. The existing pull up and the transistor are both under the LCD module which is not easy to to desolder, ia lot of pins in tight metalized holes.The backlight is very bright and it is better to control it with PWM. That definitely requires the hardware modification or you may overload and blow up that Arduino pin as it is always in output mode.I use these modules also with a WEMOS ESP8266. Those output 3V but it works just fine. The board sees 3V as a valid high level. The additional mod needed there is a 8k2 resistor to ground from A0 to limit the input to 3 V. It does not leave a whole lot of I/O pins to use, but it works. Do adjust the switch analog values for this.

This LDC module really works great with the Arduino Uno. I like the fact that there is a dimming control to control lighting. I purchased this display module to make a Sky Quality Meter who's design is on the web that measures night time light pollution. To make measurements more accurate I used pin 10 to turn off the display light so the optical sensor doesn't see it. When the measurement is over code turns back on the display light.The only down side to this module is that the software required the use of D8 for frequency measurement so I needed to cut the trace that as connected to Rs and instead connected it to an open digital line. If your handy with a soldering iron and an Xacto blade this is a quick task to do. For sketches that don't need D8 this is not an issue.

Straight out of the box - with an adjustment to the contrast - this works just fine. Thank you.Note - you will need to adjust the contrast - these come with the contrast way, way down - so it looks like the screen is not working. But once adjusted, the screen looks great.

Right out of the box: Shield lite up but would not display data. I used another good shield from another company and it worked fine. I sent this one back to Amazon for a refund. I do not recommend this shield, mine did not work. Just a big waste of time and money.

This is a good shield, but finding support was difficult. Here's the information that would have been very helpful to know beforehand: * LCD RS pin to digital pin 8 * LCD Enable pin to digital pin 9 * LCD D4 pin to digital pin 4 * LCD D5 pin to digital pin 5 * LCD D6 pin to digital pin 6 * LCD D7 pin to digital pin 7If you don't change the above variables, the Liquid Crystal library examples will not work. The default pins in those are different.The buttons (except Reset) are all connected through resistors to AO. The APPROXIMATE analog readings are:Select: 720Left: 480Down: 305Up: 130Right: 0 (this one goes straight to ground when closed)Also, I found that using a pair of flush cutters on the underside of this board let it sit much nicer on the Arduino, otherwise some of the through hole component legs interfere with the power port and and case you might have the Arduino in.

This LCD + Keypad may work in projects without any W5100 Ethernet shield, but not with one.I bought this for local control of.my Ham radio antenna rotator. I want to have a local system as well as remote control over Ethernet. I wanted button control and a display to tell me where I am pointing in degrees.The W5100 shields use D10 through D15. So does this shield. The W5100 especially will not work with D10. This board uses the D10 line to enable the backlight. It has a pull up with a transistor and it keeps the line high.I ended up cutting D10 out. Then I removed the LCD, removing the pins fir the LCD. I changed it to a HD44780 with I2C converter and ran it from I2C (SDA, SCL). I then mounted it is the same space with standoffs.A0 also won't work for the Keypad as the W5100 uses A0 and A1. Originally the Arduino version of this used digital lines for the switches. I removed R2 through R6 and ran wire from the N.O. side of the switches to D2 through D5 for UP-DOWN-LEFT-RIGHT control.So, basically the shield was good for supporting parts, but that was it.

Worked straight from the box. If you didn't read other reviews for the pinout, do or check D1Robot. There is a sketch to just copy and run. Adjust the "pot" for contrast just realize this style pot takes ALOT of turn to get to the other end. There are holes to solder additional headers to so you can utilize the unused pins in the area. I installed downward and the display is used through a cutout and the uno is on standoffs.There was some solder problems, so if your worried check with a meter first.

The media could not be loaded. The contrast potentiometer required several turns (5-10?) to be even remotely readable on mine. Refresh rate seems a little sluggish for an LCD but fine.

i just get it, thanks....

It take a week before arriving. If I replace it, it will take another week before arriving.Really disapointed