;   a6276.txt
;
;   20-Jun-2006  Keith Neufeld
;
;   Drive an Allegro MicroSystems A6276 constant-current LED driver chip.
;   The chip takes three inputs:
;   
;   A0	serial data in (SDI)
;   A1	clock (CK)
;   A2	latch enable (L)


;------------------------------------------------------------------------------
;   Debug system
;------------------------------------------------------------------------------

constants [[debug 0]]
;constants [[debug 1]]


;------------------------------------------------------------------------------
;   Section to manipulate A6276.
;------------------------------------------------------------------------------

constants [
    [a6276-sdi-port portb] [a6276-sdi-ddr portb-ddr] [a6276-sdi-bit 0]
    [a6276-ck-port portb] [a6276-ck-ddr portb-ddr] [a6276-ck-bit 1]
    [a6276-l-port portb] [a6276-l-ddr portb-ddr] [a6276-l-bit 2]
]

;   Push one bit into input register.
to a6276-bit :bit
    ;   Put bit on data input port.
    ifelse :bit [
	if debug [ prs "setbit ]
	setbit a6276-sdi-bit a6276-sdi-port	;   set 1 output
    ] [
	if debug [ prs "clearbit ]
	clearbit a6276-sdi-bit a6276-sdi-port	;   set 0 output
    ]

    ;   Clock it.
    setbit a6276-ck-bit a6276-ck-port	;   rising edge
    clearbit a6276-ck-bit a6276-ck-port	;   falling edge
end

;   Latch input register to output register
to a6276-latch
    setbit a6276-l-bit a6276-l-port	;   rising edge
    clearbit a6276-l-bit a6276-l-port	;   falling edge
end

;   Turn off all LEDs.
to a6276-off
    repeat 16 [ a6276-bit 0 ]
    a6276-latch
end

;   Initialize port settings and turn off all LEDs.
to a6276-init
    clearbit a6276-sdi-bit a6276-sdi-port	;   zero data input
    clearbit a6276-ck-bit a6276-ck-port	;   zero clock
    clearbit a6276-l-bit a6276-l-port	;   zero latch enable

    clearbit a6276-sdi-bit a6276-sdi-ddr	;   set pins as outputs
    clearbit a6276-ck-bit a6276-ck-ddr
    clearbit a6276-l-bit a6276-l-ddr

    a6276-off				;   turn off all LEDs
end


;------------------------------------------------------------------------------
;   Routines to tie it all together
;------------------------------------------------------------------------------

to init-all
    a6276-init
end

to powerup
    init-all
end

to startup
    init-all
end