CSS BOY screen¶
Example CSS BOY screen
(cssboy_screen.png)
Interesting to note the variation of the raw values for the two analog voltage inputs is quite different. For the photocell voltage, \(V_P\), the signal is noisy but remains close to the time-averaged value. The signal for the voltage applied to the LED, \(V_{LED}\), cycles between only two numbers: 0 and 4.868 VDC. The \(V_P\) signal is a steady voltage through a voltage divider circuit. The \(V_{LED}\) signal is the output from the pulse-width modulation DIGITAL output pin D11. In PWM, the voltage is cycled between 0 and supply (\(V_{cc}\)) so that the “on” duty cycle during the PWM period, is proportional to the desired PWM level. On a time-average, the output approximates a steady voltage, but when read as instantaneous values, only 0 or \(V_{cc}\) are returned.