Deprecate init() in favor of setup(), removing inherent i2c configuration: adxl345, am2320, bme280, bmp085, hmc5883l, l3g4200d

[devsaurus]

Fixes #1845.

• This PR is for the dev branch rather than for master.
• This PR is compliant with the other contributing guidelines as well (if not, please describe why).
• I have thoroughly tested my contribution.
• The code changes are reflected in the documentation at docs/en/*.

Having the I2C configuration included in the modules' init functions is an issue for a shared bus. In worst case it prevents coexistence with other I2C slaves on the same bus:

• adxl345.c @jschmidlapp
• am2320.c @hvegh
• bme280.c @vsky279
• bmp085.c @kbeckmann
• hmc5883l.c @jschmidlapp
• l3g4200d.c @jschmidlapp

This PR introduces a setup() function for each listed module which performs the core hardware initialization and avoids any (re) configuration of the I2C bus. The existing init() function is kept and tagged as deprecated with planned removal in (one of) the next master drop.

I don't have any of the sensors on my desk - my verification is therefore restricted to compilation and basic call tests. Tagged the related originators / maintainers of the modules, please double check the changes on real hardware.

[marcelstoer]

Can you apply these changes to #1880 as well (can be done even before we merge it)?

[hvegh]

Aha, now I understand why I had to fiddle with the timing on initialization to make it work... I always blamed it on the sensor... Thanks! I will test...

[v1993]

Can I help with testing?

[marcelstoer]

Sure, we appreciated your support. Let us know if you need help building your custom firmware from https://github.com/devsaurus/nodemcu-firmware/tree/refactor_i2c_init.

[v1993]

Note to am2320:

i2c.setup(0, sda, scl, i2c.SLOW)
am2320.setup()

failed. But

i2c.setup(0, sda, scl, i2c.SLOW)
tmr.delay(100)
am2320.setup()

is OK.

[v1993]

local sda = 3
local scl = 4

local duration = 1000

local i2c = require 'i2c'
local tmr = require 'tmr'
local am2320 = require 'am2320'

i2c.setup(0, sda, scl, i2c.SLOW)
tmr.delay(100)
am2320.setup()

local getData = function()
	local h, t = am2320.read()
	print(string.format("Humidity: %s%%", h / 10))
	print(string.format("Temperature: %s\194\176C", t / 10))
end

tmr.create():alarm(duration, tmr.ALARM_AUTO, getData)

am2320 is working.

[devsaurus]

Ah, I see. I missed the os_delay_us(1500); in the original am2320_init(). Will need to re-add that in the C code and the example.

Thanks a lot for testing!

Just noticed that I did port the os_delay_us(1500); over to am2320_setup().
The sequence of

i2c.setup(0, sda, scl, i2c.SLOW)
am2320.setup()

should be equivalent to

am2320.init(sda, scl)

I start to wonder how the latter could ever have worked.

[marcelstoer]

@v1993 FYI tmr.delay will sooner or later be removed, see #1892.

[v1993]

Also,

am2320.init(sda, scl)

is OK. I'm really confused.

[marcelstoer]

Everything ready, isn't it?

[devsaurus]

Kind of, could be merged with certain risk for untested changes in the other modules.

[FrankX0]

Can we merge? Risk of the untested changes are low.

[marcelstoer]

Can we merge?

I'd support that but I'd like to hear from other collaborators as well.