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A little strange : Propeller with the Parallax 4x20 Serial LCD (Backlit) — Parallax Forums

A little strange : Propeller with the Parallax 4x20 Serial LCD (Backlit)

markustermarkuster Posts: 184
edited 2013-07-17 11:18 in Propeller 1
Hi,

I have troubles with the Parallax 4x20 Serial LCD (Backlit).

I am using the Propeller with this LCD 4x20 .

I understand that Parallax displays have switches for testing and to select baud rates.

The testing starts when switches are set : SW1 = OFF and SW2= OFF .

My problem is that I have not switched SW1 = off and SW2= off and
the display starts the test.

Do you know if the Propeller is full compatible with the Parallax
LCD 4x20 display ?



Thanks.

Comments

  • DaveJensonDaveJenson Posts: 375
    edited 2013-07-17 10:05
    What are the switch settings you are using? I have had no trouble interfacing any of my Propellers to the LCD 4x20.
    Test mode starts when power is applied to the LCD and swiches are both in the off position. This occurs if the LCD is connected to anything or not.
  • ElectrodudeElectrodude Posts: 1,658
    edited 2013-07-17 11:12
    The switches only get read when you turn the LCD on. Switching them while it's on won't do anything until you turn it off and back on again. Turn both switches on and have your propeller output to it at 19200 (I think) baud. Are you powering the screen with 3.3 or 5 volts? I'm pretty sure that screen needs 5v power but can take 3.3v signal.
  • David BDavid B Posts: 592
    edited 2013-07-17 11:18
    If the Parallax LCD serial driver is like my Seetron LCD driver, the driver is coded to enter testing mode if the serial line is in one particular level when it powers up. (Either logic high or low, I don't remember which.)

    You may have to add circuitry to make sure the serial data-in pin is held at the non-test logic level on power-up.
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