-- Kitt Car Modified by John Longworth December 2017
-- Using pins 3 & 4 to be compatible with ESP001
-- SDA & SDL can be assigned any pin number between 1 - 12
-- Connects to MCP23008 (8-Bit I/O Expander with Serial Interface)

id=0
sda = 3  -- GPIO0 Connect to Pin 2 of MCP23008 
scl = 4  -- GPIO2 Connect to Pin 1 of MCP23008 
i2c.setup(id, sda, scl, i2c.SLOW)  -- Initialize I2C
device = 0x20 -- I2C bus address of MCP23008
IODIR = 0x00
GPIO  = 0x09

function read_reg(dev_addr, reg_addr)
    i2c.start(id)
    i2c.address(id, dev_addr ,i2c.TRANSMITTER)
    i2c.write(id,reg_addr)
    i2c.stop(id)
    i2c.start(id)
    i2c.address(id, dev_addr,i2c.RECEIVER)
    c=i2c.read(id,1)
    i2c.stop(id)
    return c
end

function write_reg(dev_addr, reg_addr, reg_val)
    i2c.start(id)
    i2c.address(id, dev_addr, i2c.TRANSMITTER)
    i2c.write(id, reg_addr)
    i2c.write(id, reg_val)
    i2c.stop(id)
end

write_reg(device, IODIR, 0x00) -- set Port A to output
i = 1
dir = 1

tmr.alarm(0,250,1,function() 
    write_reg(device, GPIO, i) 
    print("I = " .. i)
    dir = (i == 1) and (dir == -1) and 1 or (i == 128) and (dir == 1) and -1 or dir
    i = (dir == 1) and i * 2 or i / 2
end)

-- Pin Connections on my board
-- Pin 18 (VDD) to 3v3
-- Pin 9  (VSS) to GND
-- Pin 7  (NC) to GND (Not necessary)
-- Pin 1  (SCL) to ESP GPIO2
-- Pin 2  (SDA) to ESP GPIO0
-- Pin 5  (A0) to GND
-- Pin 4  (A1) to GND
-- Pin 3  (A2) to GND
-- Pin 6  (RESET) to 3v3
-- Connect pins to be read to Gnd on Port A (pins 10 - 17)