# #############################################################################
#
# Copyright (c) 2002 by Wayne C. Gramlich and Bill Benson
# All rights reserved.
#
# Permission to use, copy, modify, distribute, and sell this software
# for any purpose is hereby granted without fee provided that the above
# copyright notice and this permission are retained.  The author makes
# no representations about the suitability of this software for any purpose.
# It is provided "as is" without express or implied warranty.
#
# This is the code that implements the LED10 RoboBrick.  Basically
# it just waits for commands that come in at 2400 baud and responds
# to them.  See
#
#   http://web.gramlich.net/projects/robobricks/led10/index.html
#
# for more details.
#
# #############################################################################

processor pic16c505 cp=off wdte=on mclre=off fosc=intrc_no_clock

# Define processor constants:
constant clock_rate 4000000						
constant clocks_per_instruction 4
constant instruction_rate clock_rate / clocks_per_instruction
				
# Define serial communication control constants:
constant baud_rate 2400
constant instructions_per_bit instruction_rate / baud_rate
constant delays_per_bit 3
constant instructions_per_delay instructions_per_bit / delays_per_bit
constant extra_instructions_per_bit 9
constant extra_instructions_per_delay extra_instructions_per_bit / delays_per_bit
constant delay_instructions instructions_per_delay - extra_instructions_per_delay

# Register definitions:

# Status register:
register status 3
bind c status@0
bind z status@2

# OSCCAL register:
register osccal 5
constant osccal_lsb 4

# Define pin assignments and directions:
constant led0_bit 5
constant led1_bit 0
constant led2_bit 1
constant led3_bit 2
constant led4_bit 0
constant led5_bit 1
constant led6_bit 3
constant led7_bit 4
constant led8_bit 4
constant mode_bit 5
constant serial_out_bit 2
constant serial_in_bit 3
constant led0_mask (1 << led0_bit)
constant led1_mask (1 << led1_bit)
constant led2_mask (1 << led2_bit)
constant led3_mask (1 << led3_bit)
constant led4_mask (1 << led4_bit)
constant led5_mask (1 << led5_bit)
constant led6_mask (1 << led6_bit)
constant led7_mask (1 << led7_bit)
constant led8_mask (1 << led8_bit)

port portb b bits_and_byte read_write_static
port portc c bits_and_byte write_only
pin led0 portb led0_bit write_only
pin led1 portb led1_bit write_only
pin led2 portb led2_bit write_only
pin led3 portc led3_bit write_only
pin led4 portc led4_bit write_only
pin led5 portc led5_bit write_only
pin led6 portc led6_bit write_only
pin led7 portb led7_bit write_only
pin led8 portc led8_bit write_only

pin mode portc mode_bit read_only
pin serial_out portb serial_out_bit write_only
pin serial_in portb serial_in_bit read_only

global b_on byte
global c_on byte
global b_off byte
global c_off byte

procedure main {
    arguments_none
    returns_nothing

    variable command byte
    variable glitch byte
    variable index byte
    variable count1 byte
    variable count2 byte

    loop_forever {
	# Strobe the LED's for 600uS at 40kHz:
	count_down count1 20 {
	    portb := 0xff
	    portc := 0xff
	    nop (13 - 4)
	    portb := 0
	    portc := 0
	    nop (12 - 2 - 3)
	}
	
	# Leave everything off for 100mS:
	count_down count2 200 {
	    count_down count1 20 {
		nop (25 - 3)
	    }
	}
    }
}