CPAL Playground

/**
 * Copyright (C) 2015 RealTime-at-Work
 *
 * Using a basic 8x2 Character LCD (HD44780).
 * Tested with a Raspberry Pi and https://www.sparkfun.com/products/11122
 *
 * Author(s):
 * - Loïc Fejoz <loic.fejoz@realtimeatwork.com>
 *
 * @keywords bit banging; GPIO; Raspberry Pi; LCD
 *
 * You may use, copy, reproduce, and distribute this sample cource code for any non-commercial purpose.
 * Some purposes which can be non-commercial are teaching, academic research,
 * public demonstrations and personal experimentation. You may also distribute this Software
 * with books or other teaching materials, or publish the Software on websites,
 * that are intended to teaching for academic or other non-commercial purposes.
 *
 * In return, we simply require that you agree: 
 * 1. That you will not remove any copyright or other notices from the Software.
 * 2. THAT THE SOFTWARE COMES "AS IS", WITH NO WARRANTIES. THIS MEANS NO EXPRESS, 
 *    IMPLIED OR STATUTORY WARRANTY.
 *
 * @keywords syncIO; Raspberry Pi; bit banging; LCD
 *
 */

const time64: tsu1 = 1ms;
const time64: tsu2 = 1ms;
const time64: th = 10ms;
const time64: tw = 1ms;

processdef My_Proc(
  out bool: db0,
  out bool: db1,
  out bool: db2,
  out bool: db3,
  out bool: db4,
  out bool: db5,
  out bool: db6,
  out bool: db7,
  out bool: rs,
  out bool: rw,
  out bool: e
) {
  
  var time64: enable_pulse_width_timer;
  static var time64: last_activation_time = 0ns;
  
  common {
    if (last_activation_time != 0ns) {
      /* Checking minimum enable cycle time (except between initialisation and first activation)*/
      var time64: current_time = time64.time();
      assert(current_time - last_activation_time > 500ns);
      last_activation_time = current_time;
    }
  }
  
  state Checking_Configuration {
    var time64: th1 = th;
    var time64: th2 = th;
    assert(tsu1 > 40ns);
    assert(tsu2 > 80ns);
    assert(th1 > 10ns);
    assert(th2 > 10ns);
  }
  on (true) to Clearing_Display;
  state Clearing_Display {
    rs = false;
    rw = false;
    IO.sync();
    sleep(tsu1);
    e = true;
    enable_pulse_width_timer = time64.time();
    IO.sync();
    db0 = true;
    db1 = false;
    db2 = false;
    db3 = false;
    IO.sync();
    sleep(tw);
    assert(time64.time() - enable_pulse_width_timer > 230ns);
    e = false;
    IO.sync();
    sleep(th);
  }
  on (true) to On;
  state On {
    rs = false;
    rw = false;
    IO.sync();
    sleep(tsu1);
    e = true;
    enable_pulse_width_timer = time64.time();
    IO.sync();
    db0 = true; /* Cursor Blinking */
    db1 = true; /* Cursor On */
    db2 = true; /* Display On */
    db3 = true;
    IO.sync();
    sleep(tw);
    assert(time64.time() - enable_pulse_width_timer > 230ns);
    e = false;
    IO.sync();
    sleep(th);
  }
  on (true) {
    rs = true;
    rw = false;
    IO.sync();
    sleep(tsu1);
    e = true;
    enable_pulse_width_timer = time64.time();
    IO.sync();
    db7 = false;
    db6 = false;
    db5 = true;
    db4 = true;
    db3 = false;
    db2 = false;
    db1 = false;
    db0 = false;
    IO.sync();
    sleep(tw);
    assert(time64.time() - enable_pulse_width_timer > 230ns);
    e = false;
    IO.sync();
    sleep(th);    
  } to First_Char;
  
  state First_Char {
  }
  on (true) {
    rs = true;
    rw = false;
    IO.sync();
    sleep(tsu1);
    e = true;
    enable_pulse_width_timer = time64.time();
    IO.sync();
    db7 = false;
    db6 = false;
    db5 = true;
    db4 = true;
    db3 = false;
    db2 = false;
    db1 = false;
    db0 = true;
    IO.sync();
    sleep(tw);
    assert(time64.time() - enable_pulse_width_timer > 230ns);
    e = false;
    IO.sync();
    sleep(th);    
  } to Second_Char;
  state Second_Char {
    exit(0);
  }
}

/* DB0~DB7 */
var bool: pin0_out = false;
var bool: pin1_out = false;
var bool: pin2_out = false;
var bool: pin3_out = false;
var bool: pin4_out = false;
var bool: pin5_out = false;
var bool: pin6_out = false;
var bool: pin7_out = false;

/* Register Signal RS */
var bool: pin23_out = false;
/* read/write select signal R/W */
var bool: pin24_out = false;
/* Operation (data read/write) enable signal E */
var bool: pin25_out = false;

process My_Proc: a_task[1s](
  pin0_out, pin1_out, pin2_out, pin3_out,
  pin4_out, pin5_out, pin6_out, pin7_out,
  pin23_out, pin24_out, pin25_out);

for ms or try the desktop editor with advanced diagram views

Simulation
Tasks diagram


Quiet mode disabled
[0.000000000000:ASSIGN] Assign cpal_system new value: Scheduling_Policy.FIFO
[0.000000000000:simple-lcd-message:STARTING_TASK] 'a_task'
[0.000000000000:STATE] process "My_Proc", instance "a_task", state "Checking_Configuration"
[0.000000000000:simple-lcd-message:TASK_FINISHED] 'a_task'
[1.000000000000:simple-lcd-message:STARTING_TASK] 'a_task'
[1.000000000000:STATE] process "My_Proc", instance "a_task", state "Clearing_Display"
[1.000000000000:ASSIGN] Assign pin23_out new value: false
[1.000000000000:ASSIGN] Assign pin24_out new value: false
[1.001000000000:ASSIGN] Assign pin25_out new value: true
[1.001000000000:ASSIGN] Assign pin0_out new value: true
[1.001000000000:ASSIGN] Assign pin1_out new value: false
[1.001000000000:ASSIGN] Assign pin2_out new value: false
[1.001000000000:ASSIGN] Assign pin3_out new value: false
[1.002000000000:ASSIGN] Assign pin25_out new value: false
[1.012000000000:simple-lcd-message:TASK_FINISHED] 'a_task'
[2.000000000000:simple-lcd-message:STARTING_TASK] 'a_task'
[2.000000000000:STATE] process "My_Proc", instance "a_task", state "On"
[2.000000000000:ASSIGN] Assign pin23_out new value: false
[2.000000000000:ASSIGN] Assign pin24_out new value: false
[2.001000000000:ASSIGN] Assign pin25_out new value: true
[2.001000000000:ASSIGN] Assign pin0_out new value: true
[2.001000000000:ASSIGN] Assign pin1_out new value: true
[2.001000000000:ASSIGN] Assign pin2_out new value: true
[2.001000000000:ASSIGN] Assign pin3_out new value: true
[2.002000000000:ASSIGN] Assign pin25_out new value: false
[2.012000000000:simple-lcd-message:TASK_FINISHED] 'a_task'
[3.000000000000:simple-lcd-message:STARTING_TASK] 'a_task'
[3.000000000000:ASSIGN] Assign pin23_out new value: true
[3.000000000000:ASSIGN] Assign pin24_out new value: false
[3.001000000000:ASSIGN] Assign pin25_out new value: true
[3.001000000000:ASSIGN] Assign pin7_out new value: false
[3.001000000000:ASSIGN] Assign pin6_out new value: false
[3.001000000000:ASSIGN] Assign pin5_out new value: true
[3.001000000000:ASSIGN] Assign pin4_out new value: true
[3.001000000000:ASSIGN] Assign pin3_out new value: false
[3.001000000000:ASSIGN] Assign pin2_out new value: false
[3.001000000000:ASSIGN] Assign pin1_out new value: false
[3.001000000000:ASSIGN] Assign pin0_out new value: false
[3.002000000000:ASSIGN] Assign pin25_out new value: false
[3.012000000000:STATE] process "My_Proc", instance "a_task", state "First_Char"
[3.012000000000:simple-lcd-message:TASK_FINISHED] 'a_task'
EXIT (SUCCESS) AT 3s12ms (3012000000000)