Display an encoder count on the 2.5" LCD display

tbriggs · 2007-01-24 03:14

I am new to the propeller and am experimenting with an optical encoder. I am trying to read the encoder with the rotary encoder object and then display the count on the 2.5"LCD display. I am sure this has been done. Does someone have some code that does that so I can play around?

Thanks!

QuattroRS4 · 2007-01-24 05:14

what type of connection does your LCD have ?

Graham Stabler · 2007-01-24 08:51

He means the 2.5" LCD TV screen I assume.

Have a look at the TV text demo, it should not be too much of a stretch to add a loop and get it to display the count.

Graham

QuattroRS4 · 2007-01-24 19:44

Yeah Graham I was wondering if that is what he meant. I didn't know if we were talking vga,tv,serial lcd ... either way loads of objects out there.

tbriggs · 2007-01-24 21:19

Sorry about that. It is the 2.5" LCD that comes with the accessory kit.
The problem I am having is the encoder reading part. I have looked at the TV demo and have played with it. I guess I am not exactly sure how the encoder part works. I connected the encoder up to the bread board but I cannot tell if I am reading the encoder or not.

When I get home from work I will post my code.

Thanks!

squidx · 2007-01-31 19:12

Hi, I'm trying to do the exact same thing, but I'm a little confused with the encoder pinout. I'm using the TRD S/SH 6-wire version (AD/BD). The Quadrature Encoder spin file says to connect the encoder to two contiguous pins. So which of the wires should I be connecting? They are named Out A, Out B, Out Z, power, ground, and 0 volts.

Also, in the Quad Encoder file it says to <read [noparse][[/noparse]Pos0]>. If I want to send that value to the TV, should my call be VideoDisplay.dec(Pos[noparse][[/noparse]0])?

Thanks!

Bean · 2007-01-31 19:40

You will need to connect 0-volts to ground on the propeller.

Out-A and Out-B and the two inputs to the propeller pins, (you will need a pull-up resistor for each to Propeller Vdd (3.3V) probably 10K).

Out-Z is a home sensor.

It looks like that encoder needs power also, so you'll need to connect the power lead to whatever voltage is required.

Bean.

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Post Edited (Bean (Hitt Consulting)) : 1/31/2007 7:47:07 PM GMT

Graham Stabler · 2007-01-31 21:00

and if the encoder runs on 5v then put current limiting resistors in series with the A and B signals.

squidx · 2007-01-31 21:48

Thanks for the replies. I do have A and B coming in with 10K pull-ups to VDD, and I'm sharing ground. The encoder is actually a 12-24V model - will this make a difference?

I'm wondering if my code is also a problem? Here's the gist, A is on Pin 2, B on pin 3.

  PUB Init
  Encoder.Start(2, 1, 1, @Pos)           
           'Start continuous two-encoder reader (encoders connected to pins 8 - 11)

 
' later...
 
  repeat
      waitcnt(100_000+cnt) ' prevents flashing screen from constant updating
      VideoDisplay.out(0) 'clears screen
      VideoDisplay.str(String("INPUT COUNT: "))  
      VideoDisplay.dec(Pos[noparse][[/noparse]0])
      prev := Pos[noparse][[/noparse]0]

Thoughts?

Thanks,
Alex

Graham Stabler · 2007-01-31 22:01

try:

Encoder.Start(2, 1, 0, @Pos)

So you get absolute position not delta.

Just a thought, why not have a look at the encoder outputs on a scope or multimeter just to check they are actually switching OK.

In terms of the voltage then read the sticky on interfacing higher voltages. It may be that it has an internal reg and the output is 5v but you can check this as well.

Graham

Graham Stabler · 2007-01-31 22:02

actually ignore that bit about the deltas but notice in the docs you need to allocate memory for the delta variables.

squidx · 2007-01-31 23:41

I've looked on a scope, and it looks ok. I am also doing pulse counts on the pins, and that's working too. So it's just my use of the Encoder object code that isn't working.

When it says in the documentation to <read Pos[noparse][[/noparse]0]> , what exactly does it mean? Does anyone have any .spin code that uses the encoder that I could look at?

Thanks,
Alex

John Abshier · 2007-01-31 23:52

VAR
long pos 'Create buffer for one encoders (plus room for delta position support of 1st encoder)
OBJ
Encoder : "Rotary Encoder"
Pub Init
Encoder.Start(26, 1, 1, @Pos)
Pub MainLoop
repeat
deltaTick := Encoder.ReadDelta(0) ' reads a delta value
absolute := pos[noparse][[/noparse]0]

Graham Stabler · 2007-02-01 00:03

by <read Pos[noparse][[/noparse]0]> its just psedo code meaning get the data from the first element of that array because when you write prev := Pos[noparse][[/noparse]0] that is reading from the hub ram.

Remember that if you want one encoder and one support for delta you should define pos as

long pos

squidx · 2007-02-01 00:08

Thanks very much John! Turns out I wasn't calling my Init in main. Duh.

Alex

Zuzu · 2007-12-29 04:03

Is this thread still alive? This is pretty much where I am now. Looking to listen to an encoder and use that information to move a motor precisely. Reach critcal dampening quickly with no noise.

This cannot be as complicated as the motion control chip mfgrs make it sound.

Display an encoder count on the 2.5" LCD display

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