GPIO Library

[sjpark608]

There are two types of GPIOs on the EdgePi.

1. BCM MCU GPIOs that are controlled directly by the kernel
   • DIN1-8, DOUT1-2, IO_RST, SPARE1, SPARE2
2. GPIO expanders that are controlled using I2C comm
   • DOUT3-8, RTD_EN, DAC_GAIN, LED_OVR1-8, AN_EN1-8, GNDSW_IN1, GNDSW_IN2, RELAY_EN

Modules

1. Terminal block configuration
   • Analog/Digital input
   • Analog/Digital output
2. LED indicator

TODOs:

• [x] #86
• [x] Data classes for GPIO registers of both expander chips
• [x] peripherals required
  • [x] GPIO
  • [x] I2C it will inherit I2C to perform I2C transactions
• [x] Contain default information of each GPIO pins

edgepi_gpio

• [x] #48
  • [x] gpio only requires I2C periph
    • [x] #49
    • [x] LED array
    • [x] ADC
    • [x] RTD
  • [x] gpio only requires GPIO periph -> using gpiochip device
    • [ ] Digital Input
  • [x] gpio requires both I2C and GPIO
    • [ ] Digital Output

gpio_commands

• [x] #51
• [x] #52
• [x] #50
  • [ ] Set GPIO to the know default states, refer to issue #21

gpio_constants

• [ ] have GPIO config
• [x] #40
• [x] adc
• [x] rtd
• [ ] dout
• [ ] din
• [x] ledarray
• [x] I2C message configs
  • [x] addresses
  • [x] register configs
  • [x] register opcodes

Default values

• [x] #21

[sjpark608]

We are only interested in controlling the GPIO expanders as output sources. Section 3.5 of this datasheet illustrates register maps. The registers of interest are listed as follows

• IODIRA/B
• GPIOA/B
• OLATA/B

[sjpark608]

Usage

• [ ] The names of GPIO config are passed as string arguments to EdgepiGPIO
  • [ ] high level gpio config
  • [ ] high level gpio output state change
• [ ] Commands inherits I2c and GPIO from peripherals
  • [ ] filter gpio control methodology I2C/GPIO chip
  • [ ] it handles the gpio init/config
  • [ ] it message generation for I2C

gpio_commands

• [ ] class variable mapping GPIO name to its default state is it better to be declared as dataclass or enum?
• [ ] init
  • [x] receive gpio config string as an argument
  • [ ] depending on the config instantiate the peripheral objects
    • [x] if configs require I2C, only instantiate one I2C object
    • [ ] if configs require GPIO, instantiate the same number of gpio objects as the list of GPIO ex) DIN config requires 8 gpio objects to control all 8 gpio pins

setDefaults() function

• GpioDevice objects are already set to default state during instantiation
• I2C Devices Objects
  • check which register values to read first, the list contains the information as follow: dir, bias, port_group
  • We are interested in output regs and port config regs, check which port group to read
  • return the dictionary address : value
  • apply code value using the I2Cdev dictionary created in init

    'LED_OVR1' : ['i2c', 'out', 'pull_down',GpioBPinDir.PIN1_DIR_OUT.value, GpioBOutputClear.CLEAR_OUTPUT_1.value, 32, 'PORTB']

[sjpark608]

GPIO test failed due to a number of reasons

1. positional and keyword arguments, path, line directions are positional arguments but were passed as keyword arguments
2. spi6-extended overlay still uses GPIO 27 as CS group. Therefore the gpio library throws a device or resource busy os error. by fixing the dt overlay the test gets to pass