cap12xx - support for setting i2c address #111
Description
While sitting down with @proppy yesterday and getting something of a crash course in building drivers for Things, we ran into an omission in the cap1xxx library.
The cap1xxx range support at least 5 different i2c address that I'm aware of, via the use of a pull-down address select resistor:
| Resistor | Address |
|---|---|
| 82k | 0x2c |
| 100k | 0x2b |
| 120k | 0x2a |
| 150k | 0x29 |
| VDD | 0x28 |
The hard-coded address needs substituting with an optional constructor for supplying one of the above resistor-selected values:
I have local code working with alternate i2c addresses (Pimoroni Drum HAT uses 0x2c) which looks like this:
public Cap12xx(String i2cName, String alertName, Configuration chip, Handler handler) throws IOException {
this(i2cName, I2C_ADDRESS, alertName, chip, handler);
}
/**
* Create a new Cap12xx controller.
*
* @param i2cName I2C port name where the controller is attached. Cannot be null.
* @param alertName optional GPIO pin name connected to the controller's
* alert interrupt signal. Can be null.
* @param chip identifier for the connected controller device chip.
* @param handler optional {@link Handler} for software polling and callback events.
* @throws IOException
*/
public Cap12xx(String i2cName, int i2cAddress, String alertName, Configuration chip, Handler handler)
throws IOException {
mChipConfiguration = chip;
try {
PeripheralManager manager = PeripheralManager.getInstance();
I2cDevice device = manager.openI2cDevice(i2cName, i2cAddress);
Gpio alertPin = null;
if (alertName != null) {
alertPin = manager.openGpio(alertName);
}
init(device, alertPin, chip, handler);
} catch (IOException|RuntimeException e) {
// Close the peripherals if an init error occurs
try {
close();
} catch (IOException|RuntimeException ignored) {
}
throw e;
}
}I'm happy to raise a PR, but since this is my first Java rodeo my code may be a little rough around the edges and I'm currently missing tests for this feature.