Small 8x2 serial OLED - late Xmas present?

Technical

Technical Support
Staff member
By popular request we now have a smaller (surface mount) version of our very popular 18M2 serial OLED/LCD controller available.
Due to its smaller size it can now also be used with 8x2 OLEDs (as well as with 16x2 or 20x4 displays).

The controller is available by itself (AXE131)

AXE131_1A.jpg

www.picaxestore.com/index.php/en_gb/axe131.html

or bundled with a 8x2 OLED yellow on black display (AXE131Y)

AXE131Y_1.jpg

www.picaxestore.com/index.php/en_gb/axe131y.html

Although not specifically designed for this use, the AXE131 also makes quite a good 18M2 breakout board for those smaller sized projects.

Enjoy.
 

nick12ab

Senior Member
Looks good, that expansion header is always useful. Will it be bundled with the larger OLEDs too?

Now is this a solder spike I see?
axe131.jpg
 

wapo54001

Senior Member
I hope it include the traces and pads needed to support adjustable OLED dimming of the larger OLEDs either with 18M2 PWM or external pot? That's a capability missing from the older through hole boards.
 

nick12ab

Senior Member
I hope it include the traces and pads needed to support adjustable OLED dimming of the larger OLEDs either with 18M2 PWM or external pot? That's a capability missing from the older through hole boards.
Both boards support adjustable OLED dimming with no modifications required for potentiometer control or a single wire for 18M2 DAC control.
http://www.picaxeforum.co.uk/entry.php?1629-Winstar-OLED-Brightness-Control-Version-2-now-using-LCD-Contrast-pin-AXE133
 

hippy

Technical Support
Staff member
As far as I am aware the functionality is exactly the same as the AXE132 range, only implemented as surface mount.

It uses pretty much the exact same firmware with all Port B pins used to drive the LCD data bus in 8-bit parallel mode so, as the only PWMOUT pins are B.3 and B.6, it would seem difficult to use them for that purpose as well.

It seems modifying the display allows the brightness to be controlled via the contrast pin -

http://www.picaxeforum.co.uk/entry.php?1629.

It should be possible to fit a pot or feed PWM to the pot wiper hole which connects to the OLED contrast pin. I have no idea if the 2x8 OLED supports dimming that way or not. There are some soldered jumper pads on the module I have so it may be possible.
 

wapo54001

Senior Member
In order to enable dimming with the original board, in addition to modification to the OLED module itself, I needed to divert C.2 to the OLED module in order to use PWM to control the OLED brightness, which is necessary in order to control dimming via software. The best path for the extra wire was between the OLED module and the Picaxe board so is inaccessible after the modules are connected. I thought that perhaps since the dimming feature has been understood for a while that it might be incorporated to skip the non-standard extra wiring. Anyway, it's fine, dimming is always possible with a little extra work.

EDIT: I've just had a look at the datasheet for the new board, and it appears that the order of the output pins for 0V,5V,C.2,C.1,C.0 has changed and the +5 and 0V are at opposite ends of the row. This will make it impossible to use a standard 3-conductor servo cable to carry 0V,+5, and a data line. With the old configuration of ground and power and a data pin adjacent, it worked well to carry power and serial data to a downstream board.
 
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nick12ab

Senior Member
In order to enable dimming with the original board, in addition to modification to the OLED module itself, I needed to divert C.2 to the OLED module in order to use PWM to control the OLED brightness, which is necessary in order to control dimming via software. The best path for the extra wire was between the OLED module and the Picaxe board so is inaccessible after the modules are connected. I thought that perhaps since the dimming feature has been understood for a while that it might be incorporated to skip the non-standard extra wiring. Anyway, it's fine, dimming is always possible with a little extra work.
A wire can be soldered between pin C.2 of the PICAXE-18M2 and the wiper pin of the pot (which isn't fitted). If my blog entry is followed correctly, adjusting the voltage on pin 3 of the OLED module (connected to the wiper pin of the pot) will adjust the brightness. There is no need to have wires running to the OLED module itself.
 

darb1972

Senior Member
Very nice. Shame I blew the Christmas budget on my last order.

Will have to add this to my wish list.
 
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