i2c-exp-driver

Project for drivers to program Omega Expansions that are I2C-based.

ubus Integration

The drivers for the I2C-based Onion Expansions have been integrated with the ubus service via RPCD. They can be accessed through the i2c_exp service.

pwm-exp ubus Commands

The Servo Expansion can be programmed using the pwm-exp command in the i2c_exp ubus service:

ubus call i2c_exp pwm-exp '{"command":"String", "params": {"key": "value" } }'

The following commands are available:

• init
• sleep
• set
• set-period

Init Command

The init command will reset the chip on the Servo Expansion and enable the oscillator.

ubus call i2c_exp pwm-exp '{"command":"init"}'

Sleep Command

The sleep command will put the oscillator into sleep mode, disabling all PWM signals

ubus call i2c_exp pwm-exp '{"command":"sleep"}'

Set Command

The set command is used to generate a PWM signal on a specific channel based on a duty cycle percentage:

ubus call i2c_exp pwm-exp '{"command":"set", "params":{"channel":"<CHANNEL>", "duty":"<DUTY CYCLE>"} }'

The CHANNEL can be:

• 0 - 15
  • control an individual channel
• all
  • control all channels at once

The DUTY CYCLE can be an integer or floating point number between 0 and 100

Optional parameters:

• "frequency":"<signal frequency>"
  • Sets the PWM signal frequency
  • If not specified, default of 50 Hz is used
  • Frequency range is 24 Hz to 1526 Hz
• "delay":"<delay percentage>"
  • Adds a delay in the PWM signal, can be an integer or floating point number between 0 and 100
  • 0% delay by default

Set-Period Command

The set-period command is used to generate a PWM signal on a specific channel based on a PWM period and pulse width (both can be integer or floating point numbers):

ubus call i2c_exp pwm-exp '{"command":"set-period", "params":{"channel":9, "pulse":"1.5", "period":20}}'

relay-exp ubus Commands

The Relay Expansion can be programmed using the relay-exp command in the i2c_exp ubus service:

Set Command

The set command allows for programming the relay state:

ubus call i2c_exp relay-exp '{"command":"set", "params":{"channel":"<CHANNEL>", "state":"RELAY STATE", "address":"<ADDRESS>"}}'

The CHANNEL can be one of:

• 0 - controls Relay0
• 1 - controls Relay1
• all - controls both relays

The RELAY STATE can be one of:

• off - relay is switched off
• on - relay is switched on

The ADDRESS argument can be either:

• The DIP-SWITCH STATES
• The Hex I2C device address

Dip Switch States

The DIP-SWITCH STATES should reflect the dip switch settings in binary starting with switch 1, then switch 2, then switch 3. The 0 position is when the switch is close the numbers.

Not required when all switches are 0.

Examples:

• Switches 1 and 2 are 0 (close to the printed numbers), switch 3 is 1:
  • "address":"001"
• Switches 1 and 3 are 1, switch 2 is 0:
  • "address":"101"
• All switches are 1:
  • "address":"111"

I2C Device Address

The I2C Device Address should be just the hex address.

For example:

• 0x27
• 0x23

Get Command

The get command implements reading the current state of a relay:

ubus call i2c_exp relay-exp '{"command":"get", "params":{"channel":"<CHANNEL>", "address":"<ADDRESS>"}}'

The CHANNEL can be one of:

• 0 - controls Relay0
• 1 - controls Relay1

The ADDRESS argument can be either:

• The DIP-SWITCH STATES
• The Hex I2C device address

Dip Switch States

The DIP-SWITCH STATES should reflect the dip switch settings in binary starting with switch 1, then switch 2, then switch 3. The 0 position is when the switch is close the numbers.

Not required when all switches are 0.

Examples:

• Switches 1 and 2 are 0 (close to the printed numbers), switch 3 is 1:
  • "address":"001"
• Switches 1 and 3 are 1, switch 2 is 0:
  • "address":"101"
• All switches are 1:
  • "address":"111"

I2C Device Address

The I2C Device Address should be just the hex address.

For example:

• 0x27
• 0x23

Return Values

The ubus call will return different values based on if the command was successful or not.

Successful Command:

{"status":"success", "channel":"<CHANNEL>, "state":"<RELAY STATE>"}

Unsuccessful Command:

{"status":"success", "error":"<INFO ON ERROR>"}

oled-exp ubus Commands

The OLED Expansion can be programmed using the oled-exp command in the i2c_exp ubus service:

Set Command

The only command is the set command, it allows the relays to be programmed:

ubus call i2c_exp relay-exp '{"command":"set", "option":"opt" "params":{"<COMMAND>":"<COMMAND PARAMETER>}}'

Options

Available options are

• i
  • Initialize the display, this must be done at powerup
• c
  • Clear the screen and set the cursor to the top left"

Example Usage:

• Initialize the display
  • ubus call i2c_exp oled-exp '{"command":"set", "option":"i"}}'
• Clear the display and then write Onion Omega to it
  • ubus call i2c_exp oled-exp '{"command":"set", "option":"c", "params":{"write":"Onion Omega"}}'

Commands

The following are the commands and their parameters as accepted by the oled-exp:

• power <on|off>
• invert <on|off>
• dim <on|off>
• cursor <row>,<column>
• write <msg>
• scroll <direction>
• draw <lcd file>

Commands can be strung together!

Power

Turn the display on or off. Can be used to toggle the display after it has been initialized.

"params":{"power":"<on|off>"}

Invert

Invert black and white on the display. Setting to on will enable the invert, setting to off will disable the inversion.

"params":{"invert":"<on|off>"}

Dim

Enable dimming the display. Setting to on will dim the display, setting to off will restore the default brightness.

"params":{"dim":"<on|off>"}

Cursor

Set the cursor position on the display.

The row parameter represents each character row (8 pixel rows) on the display, so the range is 0 to 7

The column parameter represents each character column, the range is 0 to 20

"params":{"cursor":"<row>,<column>"}

Examples

Set the cursor to the start of the last character row:

"params":{"cursor":"7,0"}

Set the cursor to the middle of the 4th character row:

"params":{"cursor":"3,10"}

Set the cursor to the start of the 2nd character row:

"params":{"cursor":"1,0"}

Set the cursor to the top left (home position):

"params":{"cursor":"0,0"}

Write

Write a string to the display.

"params":{"write":"<message>"}

Notes

To get a newline on the display, need to write \\\\\n in the message.

For now, avoid the following characters:

• "
• '

Examples

Write Onion Omega to the display:

"params":{"write":"Onion Omega"}

Write Onion Corporation and then the office address on the lines below:

"params":{"write":"Onion Corporation\\\\\n187 Denison St\\\\\nMarkham, ON\\\\\nCanada\\\\\nL3R-1B5"}

Scroll

Enable scrolling of whatever is currently on the display.

"params":{"scroll":"<direction>"}

Directions

Available directions:

• left
• right
• diagonal-left
• diagonal-right
• stop
  • To disable scrolling

Draw

Display an image from an LCD file on the display.

Details on LCD file: The LCD file must be generated by the Onion utility. For a 128x64 image, there should be 1024 bytes. Each byte is one character column (8 vertical pixels), with the LSB representing the top-most pixel.

"params":{"draw":"<path to lcd file>"}