// LCD display module for IASI, BV4108 etc.
//
// Needs the asi.bas library utilities to work.
// To do this load "asi.bas", using tload and then type fsave all, this
// will save those utilities to flash.
//
// *******************************************************************
// Initailisation, run first, this will also return the LCD address
// for use in all other functions. Example of use
// adr$=asi_lcd_init$(38400)
// *******************************************************************
function asi_lcd_init$(baud)
dim rv$[:6]
    // check to see if asi.bas is loaded by looking for "asi_find$"
    if fexists("asi_find$") = 0 then
        print "Need to load  asi.bas and save to Flash, first"
        exitf
    endif    
    rv$=asi_find$(baud)
    if len(rv$) <> 0 then
        // strip '>' not needed for address
        rv$=chr$(asc(rv$,1))
    else    
        print "Device not found"
    endif
    result rv$    
endf

// *******************************************************************
// clears display
// *******************************************************************
function asi_lcd_clr(addr$)
dim t$[:6]
    t$=asi_write$(addr$+"c1")    
    if t$<>">" then
        print "error writig to LCD"
    endif    
endf

// *******************************************************************
// turns on/off back light
// use: asi_lcd_bl(1)  // turns on BL
// *******************************************************************
function asi_lcd_bl(addr$,on)
    if on=1 then 
        asi_write$(addr$+"b1")
    else    
        asi_write$(addr$+"b0")
    endif
endf

// *******************************************************************
// moves cursor to a particular point on the display, works with
// up to 4 lines and assuems the standard constants. pos is the
// position along the line starting at 0
// line 1-4, pos 0-? (depends on display, 16, 20 or 40)
// example
// isa_lcdLine("a",2,5) // move cursor to 2nd line, 6th postion
// *******************************************************************
// Change these for your particular display
constant line1 0x80
constant line2 0xc0
constant line3 0x94
constant line4 0xd4
//
function asi_lcd_line(addr$,line, pos)
dim d, t$[:6]
    select line
        case 1 d=line1+pos
        case 2 d=line2+pos
        case 3 d=line3+pos
        case 4 d=line4+pos
        default print "what? max of 4 lines, line=";line
    endselect    
    // 'c' is the command write, see BV4108 datasheet
    t$=asi_write$(addr$+"c"+hex$(d))
    if t$<>">" then
        print "error writig to LCD"
    endif    
endf

// *******************************************************************
// sends a string to the display at the current cursor position
// *******************************************************************
function asi_lcd_string(addr$,s$)
    // uses the t'data' command, could also use
    // the 'd' command
    asi_write$(addr$+"t"+*39+s$+*39)
endf    


// ===================== TEST
// use an a 4 line display, writes numbers to all for corners
function xx
dim addr$, j
    addr$ = asi_lcd_init$(38400)
    asi_lcd_clr(addr$)
    asi_lcd_line("a",2,4)
    asi_lcd_string(addr$,"Hello World")
    for j = 1 to 100
        asi_lcd_line(addr$,1,0)
        asi_lcd_string(addr$,j)
        asi_lcd_line(addr$,1,17)
        asi_lcd_string(addr$,j)
        asi_lcd_line(addr$,4,0)
        asi_lcd_string(addr$,j)
        asi_lcd_line(addr$,4,17)
        asi_lcd_string(addr$,j)
    next    
endf