According to the datasheet, C1P,C1N,C2P,C2N should be left unconnected.
VCC is the panel driving supply and can't be less than VDD, but yours doesn't seem to be connected to any supply at all?
Iref sources VCC-2.5V internally and the resistor should provide 12.5µA of sink current for 100µA drive current at a contrast value of 255. Apparently this is normal? So the value of the external resistor between GND and the Iref pin should be R=(VCC-2.5)/12.5µ. Conversely, the 390kΩ on the schematic suggests a VCC of 7.375V... does that look right? If VCC were 12V this should be 760kΩ.
Actually, you will find that the CS line is needed from the micro if you are doing SPI, in the Adafruit circuit, CS is pulled up to 3.3V by R4 and pulled down by the control processor thru D1, in much the same way the D/C and reset control lines are handled.
This is a hack to make their module work with old school 5V logic levels as well as modern 3.3V ones, but you will need those signals in any event.
Regards, Dan.
May I ask an unrelated question?
Are the raw display flex contacts something that can be soldered by hand?
I was actually thinking of laying out my own PCB before I ran across this thread.
May I ask an unrelated question?
Are the raw display flex contacts something that can be soldered by hand?
I was actually thinking of laying out my own PCB before I ran across this thread.
The metal ends on the flex LED display above can be soldered/unsoldered by hand yes.
It's a little more difficult than normal soldering and you have to be careful since it's flex and easier to damage.
But yes, if a flex cable has those solder covered pads on the end then they're solderable using an iron.
However you cannot cut a flex and then solder it to something. It must have an end that was prepared for soldering with exposed metal on both sides.
RST needs to be held low long enough to be recognized when power is first applied, and then allowed to go high. The capacitor is more than just a filter in this case.
RST needs to be held low long enough to be recognized when power is first applied, and then allowed to go high. The capacitor is more than just a filter in this case.Aha! very interesting, thank you. I'm glad I asked
My limited understanding was that there are two modes of power, one where Vcc is supplied externally which is 9v for driving the OLEDs and VDD is supplied separately as the logic voltage level (3.3v?).
and the other is where Vcc is generated by an internal DC/DC voltage converter so the whole system can be supplied by 3.3v
So I stumbled onto a schematic (see attached) for the pre-made OLEDs with PCB like you find on Amazon or AliExpress. I'm going to change my design to better match this one.
I also found another I2C hook-up guide for MCUs that seems to concur with most of the other schematic.
What I don't get is this reset circuit-- It has a 10k pull-up but also a diode and a filter cap? If RST/RESET is an input, and not interfacing to the MCU, what's the point of this?
if(_rst >= 0) {
// Toggle _rst low to reset
pinMode(_rst, OUTPUT);
digitalWrite(_rst, HIGH);
delay(100);
digitalWrite(_rst, LOW);
delay(100);
digitalWrite(_rst, HIGH);
delay(200);
}
Also, their library twiddles the reset pin (if specified, if not it's assumed to be tied to the MCU reset pin) during init:
RST needs to be held low long enough to be recognized when power is first applied, and then allowed to go high. The capacitor is more than just a filter in this case.Aha! very interesting, thank you. I'm glad I askedFor extra credit, see if you can figure out what the diode is for.
RST needs to be held low long enough to be recognized when power is first applied, and then allowed to go high. The capacitor is more than just a filter in this case.Aha! very interesting, thank you. I'm glad I askedFor extra credit, see if you can figure out what the diode is for.
Hmm I'm not sure.. Does it discharge the cap quickly but allow it to charge up slowly, or something like that?