Nov 15, 2011

2.4GHz (WiFi) Arduino Spectrum Analyzer - Part 2, Display

As a practical approach to this project, I could have started with getting the CYWM6935 module working or testing out the graphical LCD. If I could not get either one working, I would have just stopped. There was code for both of these, but the Nokia LCDs had more examples and a simpler datasheet(!). I figured if I could get the LCD working and fail on the wireless module, I was still ahead. Graphical LCDs can be used in lots of projects.

My first step was to get a Nokia 3310 to play with. These are readily available on ebay and elsewhere for around $10. What you get is a faceplate, LCD on glass, and fine-pitched connections. The pads on the LCD normally are connected with Elastomeric (Zebra brand) connectors.

Click on picture to enlarge
Although I've soldered a fair number of kits and boards, I found it very difficult to wire connections to the 1.15mm pitch of the pads, but others have found workable solutions. I tried Starlino's approach of salvaging ribbon cable from an old DVD drive, but couldn't find cable that matched the pitch, it was off just a bit. Others have made breakout boards by etching purpose-built PCB's that change the pitch from 1.15mm to 2.54mm (0.1").

So it was off to ebay to see if I could find any clones of the Nokia 3310 LCD. The first one I found was this nice one from MDFly which came with a 10 pin 2mm pitch IDC connector for around $10.
The IDC ribbon connector was female on both ends, making it easier to use the 2mm pitch of the header: push one female end onto the keyed box header on the LCD's base, push thin male jumpers into the other end. After that, I could use the male jumpers to attach to a standard 0.1"/2.54mm spaced breadboard. OK! Progress.

However, this wasn't going to work well for me in my desired case. I wanted the smallest possible enclosure for the WiFi Analyzer, and the 10 pin IDC cable, folded over or turned into origami, would take up too much space. So it was back to ebay to see what else was available.
Found this Nokia 5110 clone from MIB Instruments, also available for about $10, free shipping from Hong Kong. The MIB Instruments N5110LCD has the same specs as the original Nokia 3310 and the MDFly versions: 84x48 pixels; uses Philips PCD8544 LCD controller; operates on 2.7V to 3.3V. What's nice for me is that the N5110LCD has 8 solder holes at the base of the unit, with standard 0.1"/2.54mm pitch. I could solder header pins onto the LCD. Those headers would fit into matching female headers soldered directly onto a PCB. That would save a lot of space from not having to route wires around.

Note: I used female headers to connect the LCD on my final hand-soldered board. I could have soldered the LCD headers straight onto the board and saved some vertical space. But I usually build my projects with reuse in mind. If the LCD is attached via female headers, I can easily remove it and use it somewhere else.

Another good source of Nokia 5110 LCD clones is Included for the current $10 price is a level shifter. LadyAda has also written a nice, easy-to-use graphics library for these devices. Highly recommended!

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