LCD/LED/OLED assorted displays 'lucky bags' at Maplin 1 (N01CG) Kemo Electronic S043
by, 30-12-2012 at 23:54 (10437 Views)
Finally a bargain at Maplin - this for only £3.99 - not a 'limited time special offer' either. Although it now probably is limited time as the datasheet now shows a different selection that does not include the AMPY2001-11 HD44780-compatible LCD but it still includes the OS96016PP08MB2B10 OLED display.
Yes - the display options do include a HD44780-compatible LCD (AMPY2001-11) which has a built-in button and two LEDs and also an OLED display. Best of all, almost every component can be used with a PICAXE and they are actually useful (rather than useless 'just-for-fun' gimmicky components that you'll never actually use for a real application).
All of the five that I saw in store (the first time) had one HD44780-compatible LCD and two OLED displays per bag. In addition, there was one 1cm high 4-digit 7 segment display, two 0.5" 7-segment displays, two 0.3" 7-segment displays, an 8-LED light bar (not a bargraph display), and finally either a rectangular LCD (5cm diagonal) which requires those elastomeric connectors and has various 7-segment patterns or a surface mount 7-segment LED display. All the LED displays are red and the OLED is blue. The LEDs on the HD44780-compatible display are bright red.
At £3.99 this pack is cheap not only compared to Maplin prices but compared to eBay prices too!
Kemo stick whatever cheap surplus stuff they can get their hands on in the bag so the contents will vary from time to time. Here are some of the items you can get (click image for big version):
Going left to right, down to the next row, then left to right again the displays are:
- Small 7-seg: LTS-3361JD
- Small 7-seg: HDSP-C3L3
- Normal 7-seg: unmarked
- 4-digit 7-seg: TDCR1050M
- Large 7-seg: HDSP-4201
- SMT small 7-seg: KCSA39-105-EB
- 18-pin LCD glass: DGL-0401YG-4EH
- LCD that requires elastomeric connector
- Tiny LCD that requires elastomeric connector
- OLED: OS96016PP08MB2B10
- HD44780-compatible LCD: AMPY2001-11
- Large 7-seg: HDSP-C1G3
- LED bar: LTL-2685HR
- SMT 2 digit 7-seg: KCDC04-105
I wouldn't recommend just buying them on the website as you don't get to see what's in the bag unlike in store. I've previously seen these bags with an inferior selection in store - no HD44780-compatible display, just a few LCDs that require that elastomeric conectors and a few single-digit 7-segment displays and '+1' displays - so you might end up with one of those instead. Also the displays aren't individually packaged and they have the potential to damage each other in the packaging so you'll want to check for that before you buy.
Oddly the bare glass LCDs get no mention in the 'datasheet' (which shows nothing other than the pinouts)
Items that will be covered here:
The 7-segment displays and bare glass LCDs will be covered in the other blog entry: LCD/LED/OLED assorted displays 'lucky bags' at Maplin 2 (N01CG) Kemo Electronic S043
- AMPY 2001-11 LCD
- OS96016PP08MB2B10 OLED
Varitronix HD44780-compatible LCD
I've put the pinout here but reversed it because the pinout in the datasheet is for the view from the back but you'll usually be wiring it when looking at the front so the reversed pinout can cause you to incorrectly wire the display (and did for me).
After doing some investigation, it looks like these are surplus displays from a power meter. The L1, L2 and L3 symbols suggests that it was a three-phase power meter and the markings suggest that these displays were commissioned by Ampy Metering.
This blog entry isn't advertising blurb - there is no documentation included for the HD44780-compatible display apart from a pinout and I couldn't find a datasheet on the internet which was a pain when I discovered that it's a 16x1 LCD with a second row of symbols! The characters themselves are also only 5x7 instead of the more usual 5x8 so take that into account if you want to use CGRAM characters on the first row or the visible cursor.
The symbols are addressed like the characters on a second row of a 16x2 LCD would be. The pixels on the first row of the 5x8 character control the individual parts. See the table below - these pixels are numbered from 1 (top left pixel) to 5 (top right pixel). The character locations for these symbols is about the same as for the 5x8 characters on a 16x2 LCD, but the 'h's are controlled by the character location following the kW/kVar that they are associated with. Also, the ∇ and ! are controlled by the same pixel.
There's no need to define CGRAM characters to use the symbols - certain letters will activate the right pixel(s) and other pixels don't matter. Examples: 'D' for first pixel, 'B' for the first and second to last pixels, 'I' for the second to last pixel only, 'J' for the two last pixels, 'd' for the last pixel only and 'E' for all three pixels.
The LEDs are controlled using transistors built-in to the module and the resistors are built in too. The anodes of the LEDs are connected to one side of the button so that means that if you want to use the LEDs then the button must be wired between power and the input pin, not ground and the input pin.
The only downsides are no backlight, no pin for a manual contrast control without modifying it (see below) and the symbols mean that you cannot change the viewing direction (which is 12:00). There is a built-in resistor for the correct contrast level at 4.5-5V but if you want to use the display at 3V and use a negative voltage generator charge pump for the contrast control, you'll need to mod it. Once modded, the LCD module can be powered by 3V if an external negative voltage generator is used. If you won't use the symbols, you can initialize the LCD for one line (instead of two) which will be beneficial if using 3xAA batteries.
To add an external contrast control, R13 needs to be removed and a wire run from the VLCD pad to the unused pin 18 on the connector as shown in the picture below. Click the picture to view full size.
The OLED uses an SSD0303 and gives you many interface options including parallel, SPI and i2c. The pinout of the OLED can be found on page 44 of that datasheet as well as the leaflet included with the pack of assorted displays. The OLED is also easily dimmable through software commands, unlike some OLEDs which require modification.
The OLED is blue - the shade of blue it uses looks nice in real life and is a deeper shade than in the photo above - the screen burn-in example below is closer to the real colour. Oddly the OLED also needs to be up side down to get the correct addressing - you'd expect the right way up to be with the tab at the bottom but the right way up is with the tab at the top - but that does allow you to fold the tab behind the OLED and have the breakout board with the pins at the bottom. The SSD0303 command set does allow you to 'reverse' the addressing but that only works somewhat and just caused confusion when I tried it.
Use of an adapter board like the one shown in the photo (search for 'tft to dip' on eBay) is essential if you want to use the display on breadboard or stripboard - you can't just solder jumper wires to the connections and bend them to fit in a breadboard since the connections are fragile and you will break them if you do this. This is another reason to inspect the displays before buying the bag - the displays are just floating around in the bag so the fragile connector could get damaged on another display.
Note: These OLED Displays are very vulnerable to screen burn (particularly on the brighter settings), unlike the Winstar OLEDs sold by Rev-Ed. Running the clock demo for more than a few minutes on the bright setting or a few weeks on the dimmest setting will cause visible screen burn-in.