Connect uOLED-128-G1 to propeller
ncweiler
Posts: 4
Having problems getting the uOLED-128-G1 (#27925) to work reliably on a Propeller robot control board (#28230, discontinued). As long as I have the control board connected to my computer via USB without the resistor on pin 5 of the display, the display works fine. The display quits working after I unplug the USB cable or add the resistor.
I'm not sure I have the resistor wired correctly and I think this is the cause of the problem. The color bands on the resistor I'm using are brown, black, orange, gold and it is supposed to be a 10k ohm resistor.
If I connect the display directly to the I/O pins AND have the USB cable connected, the display works fine.
Can any one see what I'm doing wrong.
I'm not sure I have the resistor wired correctly and I think this is the cause of the problem. The color bands on the resistor I'm using are brown, black, orange, gold and it is supposed to be a 10k ohm resistor.
If I connect the display directly to the I/O pins AND have the USB cable connected, the display works fine.
Can any one see what I'm doing wrong.
Comments
The display needs 5 volts to work, but the propeller is a 3.3v micro. The 10k is needed for signals *from* the 5v display to the 3v3 Propeller, to protect the propeller's input pin from overvoltage, but this should be on pin 3 (which transmits 5v data from display to input pin on the prop) rather than pin 5.
I take it your display is one of the newer kind that has a 10 pin connector, rather than the old that had 5 pin connectors. So when you say pin 5 you mean one in the middle, right?
You don't need resistors on the other two signals that go to the display, since the 3v3 signalling is acceptable to the 4d display
I suggest measure the voltage seen at the display - it needs 5 volts, it could be you lose voltage when USB is unplugged for some reason (many possible reasons)
cheers
tubular
Oh, and welcome to the Propeller forums!
I've got one of the newer 10-pin displays. Has Revision 1N and Copyright 2011 printed on it. Splash screen says uOLED-128-G1h.
The diagram below shows how I currently have the display connected to the Propeller chip.
Display Propeller Pin Pin -------------------- 1 +5v 3 P7 5* P6 7 Gnd 9 P5 * Run this pin from the display to a breadboard. I have the resistor on this pin. Resistor color code: brown, black, orange, gold. uOLED-128-GDM1 ┌────────────────┐ │ │ │ │ │ SCREEN │ │ SIDE │ │ │ │ │ │ 9 7 5 3 1 │ └─┬─┬─┬─┬─┬──────┘ │ │ │ │ │ P5┘ │ │ │ └─Vcc (+5v) │ │ │ Gnd┘ │ │ ┌─┤ └─P7 │ │ │ │ │ └─ P6 │ 10K Resistor │ Vcc (+3.3v)