' Program Listing 21.1. BS1 Program to Demonstrate TSL230
' Program: TSL230.BAS (Interface with TSL230 light sensor)
' This program demonstrates the light-to-frequency conversion
' capability of the TSL230 sensor from Texas Instruments.
' BS1 pins 0 and 1 control the sensitivity of the '230 through
' its "electronic aperture" feature. The higher the sensitivity,
' the higher the frequency output for a given light intensity,
' as shown below:
' bit1 bit0 Sensitivity
' ---- ---- -----------
' 0 0 sensor OFF
' 0 1 x1
' 1 0 x10
' 1 1 x100
' Since the BS1 measures pulse width rather than frequency, its
' response is reciprocal; larger numbers mean less light. The program
' reverses this by dividing the light-dependent value into 65535.
' The program displays its readings on a 2x16 serial LCD module.
SYMBOL sens = b2 ' Sensitivity setting.
SYMBOL mult = b1 ' Multiplier for a given sensitivity.
SYMBOL light = w2 ' Light-intensity reading.
SYMBOL I = 254 ' Instruction prefix for LCD.
SYMBOL one = 128 ' Address of 1st LCD line.
SYMBOL two = 192 ' Address of 2nd LCD line.
dirs = %00000011 ' Make pins 0 and 1 outputs.
again: ' Main program loop. for sens = 1 to 3 ' Walk through sensitivity settings.
pins = sens ' Write sensitivity setting to pins. lookup sens,(0,1,10,100),mult ' Get the sensitivity multiplier. pulsin 2,1,light ' Take a light reading. light = 65535/light ' Compute reciprocal. serout 7,n2400,(I,one,"multiplier: x",#mult," ") ' Display. serout 7,n2400,(I,two,"light: ",#light," ") pause 1000 ' Wait a second between readings.
next ' Next sensitivity. goto again ' Repeat forever.