OLED with nice options

#1
I've been looking for an OLED display that is of a size of the AXE133Y but could display larger characters.

I found that there were code samples out there that would hack a 16x2 display to display a single line of larger characters, but not for the Picaxe.

I've just found an OLED board that seems to do everything I want. It's more expensive at $40 for the 2-line and $49 for the 4-line, but if you want bigger letters for readability or customized appearance or custom symbols it might be worth it.

1. Mixed fonts
2. 5-step brightness & OFF
3. data rate to 9600bps for the two line, 38.4kbps for the four line
4. displays ASCII codes 32 to 127 AND permits custom programming of 16 characters.

Detailed programming info in their "Programmer's Reference" page.

You will find their website here: http://www.seetron.com/index.html
 

nick12ab

Senior Member
#2
Product pictures have the Winstar label blurred out though the product code on the PCB itself is not. The OLED displays are 100x32 graphic versions of standard Winstar OLEDs (which are available to buy in the UK) though the serial driver board, not the OLED, is responsible for the characters which makes it a more difficult path for those wanting to eventually upgrade to using the parallel interface.

I'm interested in the brightness setting though - have they discovered an undocumented command? If you've bought one could you check what happens over the parallel interface? This could possibly be applied to character displays as well.
 
#3
I'm interested in the brightness setting though - have they discovered an undocumented command? If you've bought one could you check what happens over the parallel interface? This could possibly be applied to character displays as well.
I just found it, I don't have one to evaluate. If it's the standard Winstar OLED, I wonder if they are using some kind of switching technique to cause apparent dimming. If so, it would be electrically noisier than a standard full-on display.
 

nick12ab

Senior Member
#4
I just found it, I don't have one to evaluate. If it's the standard Winstar OLED, I wonder if they are using some kind of switching technique to cause apparent dimming. If so, it would be electrically noisier than a standard full-on display.
The serial driver board does not appear to have any other connection to the module other than the 16-pin connector (which has all 16 pins connected) indicating the possibility that it's done through that.

The seller doesn't seem to give much information about his proprietary modules away, even bluring out the Winstar label in pictures.

Turning the display on and off using HD44780 commands at high frequency is unlikely to be the method since it would cause flicker, plus either part of the display to go missing or be brighter than the rest as the oscillator in the OLED drifts and the hardcoded timing is no longer correct.
 
#5
I would not mind buying one for that price, but they want $75 to get it to the UK! Time to start looking for the UK source of just the graphics display and write my own driver.

-- a couple of minutes later and I have a supply of a 100x32 display http://www.rapidonline.com/electronic-components/oled-dot-matrix-graphic-displays-519241 for ~£30 UK less than a US supplier, a nice OLED graphics display though, so thanks for the links...
 
#6
-- a couple of minutes later and I have a supply of a 100x32 display http://www.rapidonline.com/electronic-components/oled-dot-matrix-graphic-displays-519241 for ~£30 UK less than a US supplier, a nice OLED graphics display though, so thanks for the links...
I don't think I see the parallel between these displays -- the Seetron displays require no programming of graphical characters (which is why I am feeling enthused), rather, each display provides a set of appropriate fonts for use and it's practically as simple as using the AXE133Y. The Seetron are not intended to display graphics, they are intended to make it easy to use large fonts and mixed fonts on any display page.
 
#7
The serial driver board does not appear to have any other connection to the module other than the 16-pin connector (which has all 16 pins connected) indicating the possibility that it's done through that.

The seller doesn't seem to give much information about his proprietary modules away, even bluring out the Winstar label in pictures.

Turning the display on and off using HD44780 commands at high frequency is unlikely to be the method since it would cause flicker, plus either part of the display to go missing or be brighter than the rest as the oscillator in the OLED drifts and the hardcoded timing is no longer correct.
Since I'm seriously interested I asked questions via email and here are parts of the reply I got:

With separate regulators, noise from the OLED would be below the threshold of measurement in the other-circuit leg. If the OLED shares a Vreg, you can anticipate 100mV+ noise showing up on the supply rail (with typical LDOs). So splitting the supplies is the way to go.

The dimming capability has very little to do with the noise. The OLED has a jumper-configurable control-voltage input that can adjust the OLED duty cycle. We use a few IOs to provide different DC voltages to this input via a resistive voltage divider. (No PWM on our end.) At this point in the development of these OLEDs, you only get lo-med-hi adjustment, not a smooth/continuous range by any means. It's useful primarily for dimming the OLED to (for example) preserve the driver's night vision in a vehicular application.
Since I've already designed the separate regulator solution into my project, I will proceed. Their spec sheet states 50ma max for the 16x2 and 60ma max for the 20x4, so pretty close to the AXE133Y.

Having access to several different sizes of font would be extremely desirable for reading from a distance, and it can be done without programming. One thing that never occurred to me before -- storing graphics takes a lot of space and you have to consider that when selecting a graphics solution. I think some Picaxes would not have the storage available to do anything elaborate in that regard.
 

erco

Senior Member
#8
Very interesting. Scott Edwards has been selling various LCD modules for ~20 years now. I still have one or two of his very first serial LCD modules circa ~1995, back when the BASIC Stamp 2 was the only game in town.
 

nick12ab

Senior Member
#9
I don't think I see the parallel between these displays -- the Seetron displays require no programming of graphical characters (which is why I am feeling enthused), rather, each display provides a set of appropriate fonts for use and it's practically as simple as using the AXE133Y. The Seetron are not intended to display graphics, they are intended to make it easy to use large fonts and mixed fonts on any display page.
All the fonts are implemented in the serial driver IC, not the Winstar OLED.

Since I'm seriously interested I asked questions via email and here are parts of the reply I got:
The dimming capability has very little to do with the noise. The OLED has a jumper-configurable control-voltage input that can adjust the OLED duty cycle. We use a few IOs to provide different DC voltages to this input via a resistive voltage divider. (No PWM on our end.) At this point in the development of these OLEDs, you only get lo-med-hi adjustment, not a smooth/continuous range by any means. It's useful primarily for dimming the OLED to (for example) preserve the driver's night vision in a vehicular application.
So the secret is revealed! Now time to compare the jumpers on the stock Winstar OLEDs with those in the picture and see if the 16x2 model can be made dimmable this way.
 

Technical

Technical Support
Staff member
#10
The controller chip that is on the OLED itself has always had a variable duty cycle (1/16, 1/64 etc.) so the same chip can be used on various different size displays.
So if you you use it in the 'wrong' mode (ie 1/64 on a 16 character display) it would appear dimmer as is suggested here.
However we are not aware of any documentation that says this feature is brought out to a pin, it appears to be generally hard wired on the various size PCBs.
 
#11
The OLEDs have pin 3 connected to the JVO jumper which is normally open.

Unfortunately simply closing this jumper and adding a potentiometer to pin 3 doesn't produce a working brightness control, so it looks like the only way to find out how it's done is for someone to buy one.
 
#12
Success!

Ignore my last post, there's no need to buy that.

Normally the side of JVO that isn't connected to pin 3 is connected to Gnd through JV (no 'O') which on the Rev-Ed size 16x2 module is right next to the JVO jumper. Removing the 0 ohm resistor from JV allows use of pin 3 (use the 0 ohm resistor on JVO).

With JV open and nothing connected to pin 3, the display is very dim with missing pixels at Vdd = 3V and dim but usable at Vdd = 5V.

With a 10k potentiometer connected between Vdd and Gnd, when Vdd = 5V one eighth of a turn at the Gnd side goes from brightest to dimmest, and at Vdd = 3V, it's one quarter turn.

Testing with PWM and a blog entry will follow in due course.
 
#14
This thread has kind of run away from where I started out wanting it to go, which was to make folks aware of an OLED that had good features, it was never my intent to grab someone's expertise without their permission. Maybe we should let this drop?
 
#15
Thanks for your post that advised us that Winstar were now selling a graphics capable OLED display (well for me the 100x32), which then led to viewing the display data sheets that show it has a display dimming option. I think that's not copying anyone's IPR.
 
#16
This thread has kind of run away from where I started out wanting it to go, which was to make folks aware of an OLED that had good features, it was never my intent to grab someone's expertise without their permission. Maybe we should let this drop?
This product is essentially a competitor to Rev-Ed's AXE134 and (one of) its killer feature(s) is based on a simple undocumented modification to Winstar OLEDs. It is not unfair to use the little information he's given us to find out how its done and publish it for the benefit of all PICAXE users. He simply did a better job of finding where pin 3 went than any of us on the forum did.

I will credit him in my blog entry anyway since I wouldn't have found it without him.

With regards to testing, so far I've tested that the power consumption is not abnormal when using the dimmer function - a likely reason for Winstar to keep quiet about this feature - and with both the potentiometer and PWM methods, power consumption is as expected (dimmer equals lower, 50% brightness is less than half of full current) on 3V and 5V. Power supply noise testing to follow.
 
#18
With regards to testing, so far I've tested that the power consumption is not abnormal when using the dimmer function - a likely reason for Winstar to keep quiet about this feature - and with both the potentiometer and PWM methods, power consumption is as expected (dimmer equals lower, 50% brightness is less than half of full current) on 3V and 5V. Power supply noise testing to follow.
Testing is done and I've posted the blog entry.

Winstar OLED Brightness Control - Version 2
 
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