I2C software library request

[Mike]

The current I2C software library supports three speeds: 1MHz, 400kHz, and 100kHz.  But many aftermarket I2C devices can go much faster than that, such as the small OLED displays.

Long ago I modified my local copy of the library to support an "unlimited" speed and I'm asking that this option be added to jallib.  See below.

Regards,

Mike

procedure  _i2c_wait() is
   
   if i2c_bus_speed == 255 then
      return
   if _i2c_bus_speed == 10 then
      ; i2c_1MHz
      delay_1us()
      return
   elsif _i2c_bus_speed == 4  then
      ; i2c_400kHz
      delay_2us()
      return
   else                          
      ; i2c_100kHz
      delay_5us()
      return
   end if
   
end procedure

[Mike]

The code should have been this:

procedure  _i2c_wait() is
   
   if i2c_bus_speed == 255 then
      return

   elsif _i2c_bus_speed == 10 then

      ; i2c_1MHz
      delay_1us()
      return
   elsif _i2c_bus_speed == 4  then
      ; i2c_400kHz
      delay_2us()
      return
   else                          
      ; i2c_100kHz
      delay_5us()
      return
   end if
   
end procedure

[Rob CJ]

Hi Mike,

Seems like a good addtion. I updated the library with your suggestion. If you are OK with it, I will add it to Jallib.

I also added some extra info about the bus speeds.

Kind regards,

Rob

---

Van: 'Mike' via jallib <jal...@googlegroups.com>
Verzonden: zaterdag 28 februari 2026 16:56
Aan: jallib <jal...@googlegroups.com>
Onderwerp: [jallib] Re: I2C software library request

 

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[Mike]

Hi Rob,

I tested the "no delay" speed setting on a 12F683 running on the 8MHz internal oscillator and connected to a 128x32 I2C OLED display and it worked just fine.  I'll try faster (crystals) at some point, as well as the 32MHz internal oscillator of the 12F1840 and 16F1825 that I know I have.

Regards,

Mike

[Rob CJ]

Hi Mike,

Thanks for testing. I added the update to Github. I saw that the bee package was already made so it will be in the next version.

Kind regards,

Rob

---

Van: 'Mike' via jallib <jal...@googlegroups.com>

Verzonden: zaterdag 28 februari 2026 23:14
Aan: jallib <jal...@googlegroups.com>
Onderwerp: Re: [jallib] Re: I2C software library request

 

To view this discussion visit https://groups.google.com/d/msgid/jallib/5c386650-0eb8-4b9d-ba00-333ca4fee698n%40googlegroups.com.

[Mike]

Here's some Sunday morning testing trivia.  I was surprised how slow everything was.

All testing was done on a 12F1840, since it is software selectable up to 32MHz.