Hi Rob,
Thank you for the information.
As far as sending a 0x00 prior to the command transmission was concerned,
I thought the procedure "_sh1106_start_transmission" took care of that.
Also I did try to add an extra write _byte(0x00) in the send_command
procedure.
But nothing changed. If it's too much work for you to look in to it
further, it's no problem.
I will try further to understand several libraries, but i am not very good
in the C coding.
Thank you for your effort.
Kind regards, Bill.
On Thursday, January 15, 2026 at 10:24:37 PM UTC+1 Rob CJ wrote:
> Hi Bill,
>
> Update. I looked at the attached Arduino library and they send a lot of
> commands during initialization like yoiu do using the procedure
> sh1106_command(). This procedure is as follows for IIC:
>
> void Adafruit_SH1106::SH1106_command(uint8_t c) {
> // I2C
> uint8_t control = 0x00; // Co = 0, D/C = 0
> Wire.beginTransmission(_i2caddr);
> WIRE_WRITE(control);
> WIRE_WRITE(c);
> Wire.endTransmission();
> }
>
> So they send all data starting with a transmission of zero. I cannot find
> in the documentation why that works but maybe it does.
>
> Kind regards,
>
> Rob
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Rob CJ <
> [email protected]>
> *Verzonden:* donderdag 15 januari 2026 18:07
> *Aan:* [email protected] <[email protected]>
>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
> Hi Bill,
>
> First quick analisys starting at the intialize routine. You start a
> transmission and then you send bytes but it does not work that way since
> the device has various registers and it needs to know to which register you
> are addressing. Instead you better call the procedure that start a
> transmission, sends the command and the data and stops the transmission.
>
> For example for setting the contrast. You use the following at the
> initialization after you have sent other data too:
> _sh1106_write_byte(_sh1106_SET_CONTRAST)
> _sh1106_write_byte(0x9F) -- A = 0x9F or 0xCF P = 0xAF
>
> But you should send the contrast command (control byte) followed by the
> contrast data in each transmission like in the procedure set_contrast()
> _sh1106_start_transmission(_sh1106_COMMAND_TRANSMISSION)
> _sh1106_write_byte(_sh1106_SET_CONTRAST)
> _sh1106_write_byte(contrast)
> _sh1106_stop_transmission()
>
> I noticed you based this on an olderversion of the ssd1306 library. In the
> newer version I removed the include of the IIC library which has to be
> done by the main program (as it should according to the JAL style guide).
>
> I hope this helps for the first step.
>
> Kind regards,
>
> Rob
>
>
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* woensdag 14 januari 2026 20:43
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
>
>
> Hi Rob,
>
> Not working at all, see picture. I studied several arduino libs but that
> didn't give me a solution.
>
> While the programmers write, that it is a small modification of the
> SSD1306, I don't see it.
>
> When I use the 1306 with this lib, the first line written from right to
> left with the text in mirrored image.
>
> Kind regards, Bill.
>
> On Wednesday, January 14, 2026 at 6:57:06 PM UTC+1 Rob CJ wrote:
>
> Hi Bill,
>
> That may take some time because those datasheets are not always that
> clear, especially Chinese ones.
>
> Have you looked at an Arduino library for this display? That often gives
> an idea about how things should work. I know for example that I could never
> have written the library for the ili9341LCD without some info I got from
> the Arduino library and I still wonder how they figured out certain
> settings while the documentation did not give any clue on that.
>
> Is nothing working or are certain things not working?
>
> Kind regards,
>
> Rob
>
>
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* dinsdag 13 januari 2026 20:24
>
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
>
> Hi Rob,
>
> I tried to make the SSD1306 library suitable for the SH1106, but it won’t
> work.
>
> Addressing the memory is different, with line, page and column addresses.
>
> Because I don’t fully understand the 1306 lib, it is difficult for me to
> make it work.
>
> Maybe you want to look at the data sheet to make some suggestions.
>
> I send the lib along. I deleted the SPI and scroll functions to keep it
> simple.
>
> Thank you in advance, and best wishes for 2026 to the group.
>
> Bill.
>
>
> On Thursday, September 25, 2025 at 9:48:13 PM UTC+2 Rob CJ wrote:
>
> Hi Bill.
>
> FYI. I finished the update of the glcd_ssd1306 library and the sample
> files. Tested it with all JAL Fonts using I2C and SPI and all seem to work
> fine.
>
> I uploaded it to GitHub so it should be in the bee package of the upcoming
> weekend.
>
> Since the version you have works for the 12x16 font it did not yet work
> for all available JAL fonts but that has been fixed. As said before, the
> IIC and SPI libraries now need to be included by the main program as to
> make the library compliant with the JAL style guide. It now also gives more
> flexibilty since you can now also use SPI 2 and I2C 2 if you needed that
> but it is a breaking change with the previous version of the library.
> Examples are given in de sample files.
>
> Kind regards,
>
> Rob
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Rob CJ <
> [email protected]>
> *Verzonden:* donderdag 25 september 2025 19:05
>
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
> Hi Bill,
>
> Good to hear that it works. As I mentioned before the IC on the module
> operates at 3.3 Volts and the pins are not 5 Volt tollerant so be careful
> with that.
>
> Today I tested the library with all available JAL fonts and they - after
> some smalle modifications to the library - all work now. I also moved the
> IIC and SPI part out of the library and moved that to the main program. The
> library checks which interface (I2C software, I2C hardware, I2C harware 2,
> SPI hardware and SPI hardware 2) is included by the main program and uses
> that interface automagically. The only setting that remains for the
> interface is the SPI software, for all others interfaces it is just
> including the required interface before including the ssd1306 library and
> it will then use that interface for the communication with SSD1306 module.
>
> I added a text with a bigger font to the current sample programs so that
> users can see that that works too. It works for I2C but I still need to
> test it for SPI as wel. If all works then I will upload the updated library
> and the updated sample programs.
>
> Good luck with the project. I think this was a nice extension of the
> functionality of this library.
>
> Kind regards,
>
> Rob
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* woensdag 24 september 2025 19:49
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
>
>
> Hi Rob,
>
> The 12x16 font now works fine, the error was on my side, the hex file
> worked fine as expected.
>
> After compilation of your program it went wrong again.
>
> After investigation, the glcd_font lib turned out to be corrupted, so I
> apologize for the inconvenience.
>
> I have looked at the I2C lines, and also see that interference signals are
>
> getting bigger as the voltage increases between 3 and 5 Volts.
>
> What I also noticed was that the pulses were not very steep,
>
> which is of course due to by the weak pullups.
>
> After placing 2 x 4k7 resistors it looked much better and realized a more
> stable data transfer.
>
> I noticed that the display regularly fails at 5V, after placing the
> resistors everything worked well at 5 Volts.
>
> According to my info there is some kind of voltage regulator on the
> display board which would make it applicable from 3 to 5 Volt.
>
> Many thanks for the good work,
>
> Kind regards, Bill.
>
>
>
> On Wednesday, September 24, 2025 at 7:01:50 PM UTC+2 Rob CJ wrote:
>
> Hi Bill,
>
> Attached the JAL testprogram I used and the hex file.
>
> Kind regards,
>
> Rob
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* dinsdag 23 september 2025 19:29
>
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
> P.S. send me the hex file for the 18F1825 so i can see of that is okay
> with my setting.
>
> On Tuesday, September 23, 2025 at 7:25:46 PM UTC+2 Bill Beek wrote:
>
> Hi Rob,
> Only the display on IC2 and 3.3V I don't understand it either, are you
> sure that the posted lib is the same as in your test?
> That could explain the problem.
>
>
> On Tuesday, September 23, 2025 at 6:34:28 PM UTC+2 Rob CJ wrote:
>
> Hi Bill,
>
> I cannot explain this. I will do some more testing and also test it with
> the SPI interface.
>
> Did you try it without any other connections to the IIC bus and at 3.3.
> Volt?
>
> Kind regards,
>
> Rob
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* dinsdag 23 september 2025 17:25
> *Aan:* jallib <[email protected]>
> *Onderwerp:* Re: [jallib] Re: Update SSD1306 library supporting bigger
> font
>
> Hi Rob,
> Some extra information about the topic.
> I tested also with a 18f1825 and sw I2C and as expected, got the same
> image as in the photo I posted.
> If the 6x8 font is used, everything works well even with the
> 18f2520, which is equipped with the tiny bootloader
> which works handy and fast for me.
> The 16F1825 is programmed with the pickit 2. I hope that you are able to
> locate the problem.
>
>
>
> Kind regards, Bill.
>
>
> On Monday, September 22, 2025 at 8:15:03 PM UTC+2 Bill Beek wrote:
>
> Hi Rob,
> Tested without the ina3221, delete the I2C code lines from the program and
> Vcc 3,3V but nothing changed.
> So I wondered if it's possible that the lib you posted is not the same as
> in your test?
> The 1306 is powered by wires under the board.
> Kind regards, Bill.
>
> On Monday, September 22, 2025 at 7:02:08 PM UTC+2 Rob CJ wrote:
>
> Hi Bill,
>
> The only thing I found is that you include and initialize i2c_hardware. As
> you may remember this is currently also done by the ssd1306 and I am not
> sure if this messes things up so I commented that part out. I also
> commented out the include of glcd_common since that is needed by the
> ssd1306 library so it is included there. I also moved the selection of the
> font but that should not make a difference. I attached the update.
>
> For the final version of the updated library you have to include and
> initialize i2c_hardware but not yet for this version.
>
> So it should work but not sure if the I2c_hardware has messed things up (I
> do not think so).
>
> Unfortunately I do not have an 18F2520 to test it.
>
> I see you have two devices on the IIC bus. Did you also test with without
> the INA3221?
>
> And to be sure. Although the module works at +5V you should not pull-up
> the SDA and SCL lines to +5Volt. If you have connected both the INA3221 and
> the SSD1306 to +5V, the INA3221 will pull-up the lines to +5V and that can
> kill the module. Last but not least. As I mentioned before the SSD1306
> module generates a lot of noise on the SDA and SCL lines and that is gone
> if you use it on 3.3 Volt.
>
> So for this test. Only connect the SSD1306 and use it (including the PIC)
> at 3.3 Volt and see if that works. If that is the case and you want to use
> it together with the INA3221 at +5V then use a level shifter between the
> PIC and the SSD1306.
>
> BTW. I do not see any power connection to the SDD1306 🙂.
>
> Kind regards,
>
> Rob
>
>
>
> ------------------------------
> *Van:* [email protected] <[email protected]> namens Bill Beek
> <[email protected]>
> *Verzonden:* maandag 22 september 2025 12:26
> *Aan:* jallib <[email protected]>
> *Onderwerp:* [jallib] Re: Update SSD1306 library supporting bigger font
>
>
> Hi Rob,
> I tested the lib but the same problem exist.
> I added your name at the lib to be sure that the right lib was used.
> You can see what's happens on the picture.
> I can't understand what I have done wrong so I added my program.
>
> Kind regards, Bill.
>
> On Sunday, September 21, 2025 at 1:38:05 PM UTC+2 [email protected]
> wrote:
>
> Hi Bill,
>
> It took me quite some time to figure this out. First of all, you cannot
> read data from the SSD1306. This means that I cannot write characters using
> pixels.
>
> So I looked at the procedure ssd1306_write_char() which writes ...
> characters. This procedure does not require the big cache that you normally
> need when writing characters as pixels or when using graphics in general.
>
> Currently the SSD1306 library worked correctly for the 6x8 font and that
> was only because that is a vertical font and that matches how the SSD1306
> displays the data. This seems to be one of the view (or the only?) vertical
> font, all other - larger - fonts are horizontal fonts and that causes the
> problem when using them.
>
> So I added code to this procedure that checks if the used font is a
> horizontal font and if so it rotates the character 90 degrees to match the
> SSD1306 display and splits the character up into smaller pieces since the
> SSD1306 works with pages (0..7) each 8 pixels high. If a font is bigger
> than 8 pixels, it needs to be spit up and divided over 2 pages.
>
> I attached the library including a picture that shows the 12x16 font
> working. I still need to test this for other font sizes and I need to clean
> the library up since currently the limit is 12x16 and if you use a smaller
> font I could save data space. So please give it try. You do not need any
> special setting for this only that you are using text mode.
>
> Next to cleaning the library up I am planning to move the IIC and SPI part
> from this library to the main program so that it is not included by this
> library anymore. This is in line with the JAL style guide but it results in
> a breaking change for anyone who is currently using the library since
> incuding IIC or SPI and initializing them moves to the main program.
>
> Kind regards,
>
> Rob
>
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