Plugging in a display doesn't do anything to either serial port. The display interface is entirely separate, and in fact the OT2m is constantly sending data to it regardless of whether there's anything connected.
Scott Micheal wrote: > > > --- In [email protected] <mailto:tracker2%40yahoogroups.com>, > Scott Miller <sc...@...> wrote: > > > > And if you're running the backlight off the T2's regulator, make sure > > it's not drawing too much current. Some of the big ones can be pretty > > power hungry. > > > > Scott > > > > Fred Hillhouse wrote: > > > > > > [Attachment(s) <#TopText> from Fred Hillhouse included below] > > > > > > Hi Steve, > > > > > > > > > PIN Symbol Level Function > > > 1 VSS - GND(0V) > > > 2 VDD - Supply Voltage for Logic(+5V) > > > > > > 3 V0 - Power supply for LCD <-- A pot between 5V and GND with the > wiper > > > connected to PIN 3 works well. The contrast can be changed as > > > temperature changes. > > > > > > 4 RS H/L H: Data; L: Instruction Code > > > 5 R/W H/L H: Read; L: Write > > > 6 E H/L Enable Signal > > > 7 DB0 H/L <-- not used > > > 8 DB1 H/L <-- not used > > > 9 DB2 H/L <-- not used > > > 10 DB3 H/L <-- not used > > > 11 DB4 H/L > > > 12 DB5 H/L > > > 13 DB6 H/L > > > 14 DB7 H/L > > > > > > ================== > > > 15 A - Backlight Power (+5V) > > > 16 K - Backlight Power (0V) > > > These connections should have a current limiting resistor added in > > > series. At least on the ones I have used in the past. Actually a pot > > > here helps to adjust the brightness as needed with a series fixed > resistor. > > > > > > I added a portion of my schematic. I don't show the VO circuit or the > > > backlight circuit either. I have a simple pot for VO. I think my > pot is > > > 20K. I am thinking my data sheet actually had a current listed for the > > > VO pin. > > > > > > I usually control the backlight with PWM (contrast too) but it seems a > > > bit overkill here. > > > You will want to limit the current to the backlight LEDs. > > > > > > The Vf is 4.2 for the Y-G version. > > > So > > > 5.0V - 4.2Vf = 0.8V > > > 0.8V / 0.180A = 5 ohms (rounded 4.44 to 5) > > > A 5 ohm resistor in series with the backlight LEDs should keep it safe. > > > > > > The Vf is 4.0 for the WHITE version. > > > So, 5.0V - 4.0Vf = 1.0V > > > 1.0V / 0.030A = 33 ohms > > > A 5 ohm resistor in series with the backlight LEDs should keep it safe. > > > > > > So depending on which model you find, either a 5 or 33 ohm resistor > > > should keep the backlight in action. > > > > > > In you want to dim it further, then a pot in series with your other > > > resistor can decrease the current (light output) without allowing > you to > > > overdrive the backlight. > > > > > > I also added pictures showing my additions to the Tracker2. And > there is > > > one of the LCD in action. > > > > > > Best regards, > > > Fred > > > > > > > New to the group, ordered the pot and display , been sketching out an > arduino circuit to handle the ascii strings coming in from the serial > port and stripping out this info. This looks much simpler. I've got a > opt+, and a TC2m plus I've built W2FS kit TNC-X (PIC bassed, just a kiss > modem only, very limited) Great job on the Argent Data system tracker 2. > I run an old HP100 PDA in my mobile setup and can see the aprs traffic > scroll by but this screen will do the trick much better. Is the screen > circuit going to disable the rs232 line? I send and receive limited > messages and talk with my base station using messages. (running DigiNed > and UIview32 in my shack) Still may replace the terminal with an AVR > butterfly to handle the basic commands like digi on and BEA, POS etc. 73 > Mike. > >
