#FriendlyARM Python GPIO#

Simple Python based interface for GPIO pins on FriendlyARM NanoPi 1.

Limitations:

• GPIO 1kHz seems about the max toggle speed on 400 MHz s3c2451.
• GPIO reaction time fluctuates due to Linux scheduling.
• PWM period is about 0.015 seconds to 30 nanoseconds
  • Kernel can be patched for other value ranges.

##Install## You can use the package directly in your project or,

If your system has Python and setuptools, you can use

 python setup.py install

##Functions## ###Init###

• fgpio.GPIO(Config())
  • Main gpio class, init with board Config()
  • GPIO, PWM, and EINT functions are all in this class.
• fgpio.boards.*.Config()
  • Board specific configuration

###GPIO### All pins listed in board config are gpio capable.

• gpio_init(pin, direction, updown)
  • Initialize pin to use, corrisponds to pinout on GPIO header on board.
  • pin: Pin number.
  • direction: Input('in') or Output('out').
  • updown: Pull Up('up') Down('down') Neither('both'), Always 0 for outputs.
• gpio_close(pin)
  • Close GPIO enabled pin and set to chip reset values.
• gpio_close_all()
  • Close all GPIO enabled pins and set to chip reset values.
• gpio_write(pin, value)
  • Write value to pin.
  • pin: Pin number.
  • value: Value 1 (high) 0 (low)
• gpio_read(pin)
  • Read pin value, returns Int 1 (high), 0 (low).
  • pin: Pin number.
  • Returns: Int
• gpio_direction(pin, direction)
  • Set direction of pin.
  • pin: Pin number.
  • direction: Input('in') or Output('out').
• gpio_updown(pin, updown)
  • Set pull up or pull down on pin (Don't use with pin as output).
  • pin: Pin number.
  • updown: Pull Up('up') Down('down') Neither('both'), Always 0 for outputs

###PWM### board config will show 'pwm' in the pin config.

• pwm_init(pin, period, duty_cycle)
  • Initialize pin as PWM.
  • pin: Pin number.
  • period: Period in nanoseconds.
  • duty_cycle: Duty cycle in nanoseconds.
• pwm_close(pin)
  • Close PWM enabled pin, sys/.../unexport.
  • pin: Pin number.
• pwm_close_all()
  • Close all PWM enabled pins, sys/.../unexport.
• pwm_get_period(pin)
  • Get period of pin in nanoseconds.
  • pin: Pin number.
  • Returns: Int
• pwm_period(pin, period)
  • Set period of pin.
  • period: Period in nanoseconds.
• pwm_get_duty_cycle(pin)
  • Get duty cycle of pin in nanoseconds.
  • pin: Pin number.
  • Returns: Int
• pwm_duty_cycle(pin, duty_cycle)
  • Set duty cycle of pin.
  • pin: Pin number.
  • duty_cycle: Duty cycle in nanoseconds.
• pwm_start(pin)
  • Start PWM output on pin.
  • pin: Pin number.
• pwm_stop(pin)
  • Stop PWM output on pin.
  • pin: Pin number.

###Interrupts EINT### Interrupt pins (EINT in config) can have a condition set, high, low, rising, falling or both, which when met on the selected pin eint_event(pin) will return 1 instead of 0. To retrigger run eint_clear(pin). These are best used in a thread.

• eint_init(pin, trigger)
  • Initialize interrupt on pin.
  • pin: Pin number.
  • trigger: 'low', 'high', 'rising', 'falling', 'none', or 'both'
• eint_close(pin)
  • Close interrupt pin.
  • pin: Pin number.
• eint_close_all()
  • Close all EINT pins.
• eint_event(self, pin)
  • Check if event triggered.
  • pin: Pin number.
  • Returns: Int 1 for triggered 0 for no event.
• eint_clear(self, pin)
  • Clear triggered event
  • pin: Pin number.

##Example Code## Sample script toggles pin 40 until pin 38 is pulled low and then exits.

    from fgpio import GPIO
    from fgpio.boards.nanopi import Config
    from time import sleep
    
    # Initialize GPIO
    gpio = GPIO(Config())
    
    # Initialize pin 40 as output (1).
    gpio.gpio_init(40, 1)
    
    # Initialize pin 38 as input (0) with pullup (2)
    gpio.gpio_init(38, 0, 2)
    
    # While pin 38 is high toggle pin 40.
    value = 1
    while gpio.gpio_read(38) != 0:
        if value:
            value = 0
        else:
            value = 1
        gpio.gpio_write(40, value)
        sleep(.5)