#! /usr/bin/python3
import cgi
import cgitb
import json
import Adafruit_PCA9685
cgitb.enable()
# read pin number from query string
form = cgi.FieldStorage()
DEFAULT_PIN=15
DEFAULT_PULSE=0
try:
    pin = int(form.getvalue("pin"))
    if not (0 <= pin <=15):
        pin = DEFAULT_PIN
except:
    pin = DEFAULT_PIN
try:
    value = int(form.getvalue("pulse"))
    if not (0 <= value <= 4095):
        value = DEFAULT_PULSE
except:
    value = DEFAULT_PULSE
pwm = Adafruit_PCA9685.PCA9685()
pwm.set_pwm_freq(50)
pwm.set_pwm(pin, 0, value)
print('Content-Type: application/json')
print()
print(json.dumps({'pin':pin, 'pulse':value}))