I2C Methods

These methods are not specific to a given i2c device but instead allow you to control any i2c device by implementing the device's protocol as specified by the manufacturer's datasheet.

set_pin_mode_i2c

 async def set_pin_mode_i2c(self, i2c_port=0, sda_gpio=4, scl_gpio=5)

    Establish the standard pico i2c pins for i2c utilization.

    :param i2c_port: 0 = i2c0, 1 = i2c1

    :param sda_gpio: gpio pin assigned to SDA

    :param scl_gpio: gpio pin assigned to SCL
    Notes

        THIS METHOD MUST BE CALLED BEFORE ANY I2C REQUEST IS MADE
        Callbacks are set within the individual i2c read methods of this API.

    See i2c_read, and i2c_write

This method must be called before calling either i2c_read or i2c_write. Using this method, select one of the i2c ports and associate the SDA and SCL pins with that port.

Note that GPIO pins 0 and 1 are not available for use.

i2c_read

 async def i2c_read(self, address, register, number_of_bytes, callback=None, i2c_port=0, 
              no_stop=False)

    Read the specified number of bytes from the specified register for the i2c device.

    :param address: i2c device address

    :param register: i2c register (or None if no register selection is needed)

    :param number_of_bytes: number of bytes to be read

    :param callback: Required callback function to report i2c data as a result of read command

    :param i2c_port: 0 = port 0, 1 = port 1

    :param no_stop: If true, master retains control of the bus at the end of the transfer (no Stop is issued), and the next transfer will begin with a Restart rather than a Start.

    callback returns a data list: [I2C_READ_REPORT, i2c_port, i2c_device_address, count of data bytes, data bytes, time-stamp]

    I2C_READ_REPORT = 10

This method allows you to read a specified number of bytes from the device.

The address parameter specifies the i2c address of the device.

The register parameter specifies the i2c register to use. If the device does not require a register to be specified, this parameter is set to None.

The number_of_bytes parameter specifies how many bytes are to be read from the device. Data is returned via callback, and therefore you must specify a callback parameter.

The i2c_port specifies which of the two i2c ports to use for this device. The SDA and SCL pins are implied as a result of the call to set_pin_mode_i2c.

Some devices require that after a read, the i2c master retain control of the bus. The no_stop parameter allows you to select this behavior.

The data returned to the callback is similar to all other callbacks. The items in the list passed to the callback function are:

[I2C_READ_REPORT, i2c_port, i2c_device_address, count of data bytes, data bytes, time-stamp]

The first element is the report type, and I2C_READ_REPORT has a value of 10. The i2c_port, the device's i2c address, the number of the bytes returned, the actual data bytes, and a time-stamp are also contained in the report.

i2c_write

 async def i2c_write(self, address, args, i2c_port=0, no_stop=False)

    Write data to an i2c device.

    :param address: i2c device address

    :param args: A variable number of bytes to be sent to the device passed in as a list. 
                  NOTE: THIS MUST BE IN THE FORM OF A LIST.

    :param i2c_port: 0= port 0, 1 = port 1

    :param no_stop: If true, master retains control of the bus at the end of the 
                    transfer (no Stop is issued), and the next transfer will begin with a 
                    Restart rather than a Start.

This method is used to write a variable number of bytes to an i2c device. You specify the i2c address, a list of the bytes to send, the i2c port to use, and a flag to indicate if the master retains control of the bus at the end of the transfer.

Example: i2c_adxl345_accelerometer.py

Example Sample Output:


TelemetrixRpiPicoAio:  Version 1.0

Copyright (c) 2021 Alan Yorinks All Rights Reserved.

Opening all potential serial ports...
    /dev/ttyACM0
Retrieving pico ID...
Pico Unique ID: [230, 96, 88, 56, 131, 120, 0, 0]
Telemetrix4RPiPico Version Number: 1.0
Raw Data:  [10, 0, 83, 50, 6, 248, 255, 7, 0, 97, 0]
ADXL345 Report On: 2021-05-04 17:36:52: 
        i2c_port=0 x-pair=248, 255  y-pair=7, 0 z-pair=97, 0

TelemetrixRpiPicoAio:  Version 1.0

Copyright (c) 2021 Alan Yorinks All Rights Reserved.

Opening all potential serial ports...
    /dev/ttyACM0
Retrieving pico ID...
Pico Unique ID: [230, 96, 88, 56, 131, 120, 0, 0]
Telemetrix4RPiPico Version Number: 1.0
Raw Data:  [10, 0, 83, 50, 6, 248, 255, 7, 0, 97, 0]
ADXL345 Report On: 2021-05-04 17:36:52: 
        i2c_port=0 x-pair=248, 255  y-pair=7, 0 z-pair=97, 0