HP3548 / HP3457 OLED display

[sagias]

fw compiled and works flawessly
i provide the filee

[cncjerry]

What oleds did you use?

[Kean]

What oleds did you use?

The ones linked earlier in the thread are no longer available, but at least the listing with specs and dimension drawing are still there.
I found another listing with similar specs, pin out, and dimensions - but I have not ordered any yet.
https://www.aliexpress.com/item/1005005770683719.html

The price of these is better that the previous listing, but I also saw some even cheaper but from "less reputable" sellers (not necessarily untrustworthy, but just lower reputation).
I will probably order 50 of them in the next couple of days as I want to convert a few meters, and can use these on other projects as well.  I guess I need to order the PCBs and other parts too...

[sagias]

As described on xyphros github

[sagias]

Prove

[Miti]

What about this OLED? Reputable and the visual area seems to be a little wider, it fills the space between digits better.

https://www.buydisplay.com/white-0-87-inch-oled-display-panel-128x32-iic-i2c-ssd1316

Edit: Ignore, the visual area is the same, just different source.

[Kean]

I've just received 20 PCBs and 60 of the previously linked OLEDs [1].  Hopefully in the next week or two I will find time to assemble a sample and check operation.
If any of the Aussie followers of this topic are interested, then feel free to DM me your interest in either bare or partially assembled PCBs.
I may have some OLEDs left over from my builds, but otherwise it is not hard to source them yourselves.

[1] https://www.aliexpress.com/item/1005005770683719.html

[TERRA Operative]

I'm currently spinning up my own version of this design and replacing the DC-DC converters with something a little cheaper.

Can someone who has built one of these measure the voltage and current draw from the output of each DC-DC converter with the displays lit to the maximum number of pixels by chance?

[TERRA Operative]

So, I've made my own spin of this board. I swapped out the expensive buck converters with cheaper options (still from TI) and optimised the layout somewhat.
I also spaced the two halves of the PCB so they can be easily cut apart with one of these. (Ignore the trace connecting the two sides, it's just to try to trick the PCB manufacturers into thinking it's not two separate designs....  )

The BOM file is such that it should be able to be dropped into JLCPCB for assembly, I think... I haven't tried so let me know how you go...

It should all just work (I made no major changes besides the DC-DC converters) so take this as a Beta version until verified by someone. 


As for the displays, you can get them on Aliexpress, but JLCPCB has them in their catalogue for their assembly service too.


I plan to get a bunch made sometime soon-ish, so I'll report back once it's done.



(See further down the thread for latest version)

[kawal]

Seems you have the wrong footprint in the BOM for U3. The SOT-23-5 should be used not SC-70-5. others seem ok

[TERRA Operative]

Seems you have the wrong footprint in the BOM for U3. The SOT-23-5 should be used not SC-70-5. others seem ok

This is the part specified:
https://www.mouser.com/ProductDetail/Texas-Instruments/SN74LVC1G86DCKR?qs=d9gICRQKuCdmtPquTT%2F3UA%3D%3D
https://www.digikey.com/en/products/detail/texas-instruments/SN74LVC1G86DCKR/381330

Note the 'DCKR' at the end of the part number in the 'manufacturer part#' in the BOM. 'DCK' indicates the SC70 package type as shown on page 1 and 14 of the datasheet.

[kawal]

Yes the that  part - the footprint in the design is for SOT-23-5 and the bom has the SC-70 part

Attached is the board with SOT-23-5 placed on it - The SC-70-5 will not fit. I found out the hard way  - by ordering boards on JLCPCB with parts per BOM. 

You need to change the BOM to show the SOT-23. Its your EDA software issue.  Mixed up  footprints.
https://www.mouser.com/ProductDetail/Texas-Instruments/SN74LVC1G86DBVRE4?qs=nqigI8dpoHLKLfGKub4Tlw%3D%3D

While you have the SC-70 version in the BOM you have the footprint for SOT-23.
Hope it will not cause mechanical assembly  issues as the SOT-23 is probably higher off the board.
Hope that is clear.

[kawal]

I am hoping to use these in a HP 3852A  that uses 2 of these displays.  Would be super nice .  Also have a few HP 66XX power supplies.

[TERRA Operative]

Yes the that  part - the footprint in the design is for SOT-23-5 and the bom has the SC-70 part

Attached is the board with SOT-23-5 placed on it - The SC-70-5 will not fit. I found out the hard way  - by ordering boards on JLCPCB with parts per BOM. 

You need to change the BOM to show the SOT-23. Its your EDA software issue.  Mixed up  footprints.
https://www.mouser.com/ProductDetail/Texas-Instruments/SN74LVC1G86DBVRE4?qs=nqigI8dpoHLKLfGKub4Tlw%3D%3D

While you have the SC-70 version in the BOM you have the footprint for SOT-23.
Hope it will not cause mechanical assembly  issues as the SOT-23 is probably higher off the board.
Hope that is clear.

Gotcha, you are absolutely correct. The footprint was indeed incorrect in the EDA software so I've made the corrections (including making my own correct footprint) and attached v1.1 of the design to this message.
v1.0 in my previous post has been corrected to reflect the correct SOT-23-5 part in the BOM too.

It looks like the SOT-23-5 part is shorter that the 2.54mm pitch pin headers when the two boards are put together (part is 1.45mm tall, board spacing is 2.54mm apart), so there shouldn't be a clearance issue to use a SOT-23-5 part.

[kawal]

Yes the that  part - the footprint in the design is for SOT-23-5 and the bom has the SC-70 part

Attached is the board with SOT-23-5 placed on it - The SC-70-5 will not fit. I found out the hard way  - by ordering boards on JLCPCB with parts per BOM. 

You need to change the BOM to show the SOT-23. Its your EDA software issue.  Mixed up  footprints.
https://www.mouser.com/ProductDetail/Texas-Instruments/SN74LVC1G86DBVRE4?qs=nqigI8dpoHLKLfGKub4Tlw%3D%3D

While you have the SC-70 version in the BOM you have the footprint for SOT-23.
Hope it will not cause mechanical assembly  issues as the SOT-23 is probably higher off the board.
Hope that is clear.

Gotcha, you are absolutely correct. The footprint was indeed incorrect in the EDA software so I've made the corrections (including making my own correct footprint) and attached v1.1 of the design to this message.
v1.0 in my previous post has been corrected to reflect the correct SOT-23-5 part in the BOM too.

It looks like the SOT-23-5 part is shorter that the 2.54mm pitch pin headers when the two boards are put together (part is 1.45mm tall, board spacing is 2.54mm apart), so there shouldn't be a clearance issue to use a SOT-23-5 part.

Ok new issues for these custom boards.  The power supplies are not starting. The 3.3v supply is 1.6V and without the 3.3V there is no 8V. Troubleshooting  this now.  Total draw is 0.6mA so obviously power supply issue.


.....


The resistor values are wrong on the 3.3V regulator. The schematic shows 16.5K and 10K  which will give 1.59V ...
The calculation for the part used  is 0.6v * (1+Rx/Ry).  You probably assumed that the part is a 1.25V reference part,  but it has 0.6V reference.   To fix this the resistor to ground needs to be 3.666k  or the resistor to output needs to be 45k.
The 8V resistors are calculated properly.
I replaced the 10K R27 with 3.6K and the supply now comes up at 3.3V and shortly after the 8V supply shows up. 

On a side note can someone confirm the Fuse settings for the atmega8 ? I assumed the following fuses  :

[TERRA Operative]

Thanks for being my alpha tester!

I'll make a revision and upload a new version with the BOM change in my previous posts.



And done.

[kawal]

The fuse settings i chooses seems to work but the startup behavior is not consistent.

I will try with brownout detection and some startup delay.

[kawal]

The fuse settings  did the trick. Each restart is clean.

[TERRA Operative]

Nice! It looks great! 

How well does it all fit on the inside?

[kawal]

The fit is good. Its a little snug to get in . The distance from to the oled is about 2.5mm too far.  if you press teh glass it will move in.  Better to have thicker spacers in between boards.  I offset the boards by about 1.3mm and added 1.2mm of tape on top of the edge of OLED.
I wish the font was a bit bigger but i don't think its possible due to decimal point.

One observation is the power usage is very low.  I got about 11mA from 12V. The original design claimed 30mA at 12V.   So the power supply is better in power usage area. This might be dependent on OLED display more than on the power supply but i cant know for sure.


Next is to test in HP 3852A  that uses 2 of these displays.  Also have a few HP 66XX power supplies to test as well.
Maciej

[kawal]

I did a recompile of the files as the triangles were not showing up from the firmware posted in github. I was getting only icons.
Attached is the recompiled Hex for triangles on the bottom.

Will not work with  HP 3852A. Strange as the original HP 3457A LCD works fine in the HP3852A. Maybe not all commands or functions are properly replicated? 

I forked the original design here:
https://github.com/kawalkQCWski/HP3457-OLED-display/tree/main

[TERRA Operative]

Can you show some photos of where it needs any adjustment to size?
I'll make another revision to improve fitment if you think it's needed.

[kawal]

Can you show some photos of where it needs any adjustment to size?
I'll make another revision to improve fitment if you think it's needed.

The PCB is good. The thickness issue is in between boards. Needs longer spacers between boards min 2mm extra.

[kawal]

Can you show some photos of where it needs any adjustment to size?
I'll make another revision to improve fitment if you think it's needed.

The PCB is good. The thickness issue is in between boards. Needs longer spacers between boards min 2mm extra.

To fit in a 3852 the ears have to be modified.  I will send you the dimensions.

[kawal]

To be able to fit in the 3852A the oled needs to be modified.  The hole on one side needs to be exactly in the middle.
The other side needs to be 10 mm from edge of the LCD display or edge of OLED PCB.  there is 2.5mm of overlap of the holes.

The only truly needed cutouts are for the capacitor. all other cutouts are optional. Its nice to have the programming cutout but that is very close to the ear.