[WIP] ADS1115 Driver

[iyer-suchet]

Describe problem solved by this pull request
Whilst designing and implementing a power monitor module for the Pixhawk, I decided to use an ADS1115 4-channel 16-bit ADC connected via I2C. This pull request aims to add a driver for the ADS1115.

Describe your solution
I found an issue (#11755) which aimed to implement the INA226 I2C driver. I approached building the driver using the INA226.cpp as a base reference, but have since moved away from it.
I am still very early on in the driver creation, but fixing the read/write operations should speed things up:

• There seems to be more data being read from the Configuration Register than expected. We are expecting 2 bytes of data (0xA243) but receiving 4 bytes of data, where the last byte is not acknowleged.
  

Additional context
Datasheet -
ADS1115.pdf

[LorenzMeier]

We unfortunately can’t really help in driver development when it comes to the device side. That would totally overload the team. Please ping us here when the PR is ready for review.

[iyer-suchet]

Of course, thank you for acknowledging. I was hoping other people attempting to arrive at a similar solution might be able to help out.

[SalimTerryLi]

I have already implemented such a driver for ads1115, but haven't create a pr due to the incomplete design of adc system. How about that we firstly work out the poorly designed adc part?

[dagar]

I have already implemented such a driver for ads1115, but haven't create a pr due to the incomplete design of adc system. How about that we firstly work out the poorly designed adc part?

@SalimTerryLi are you able to join the weekly dev call to discuss?

[SalimTerryLi]

I have already implemented such a driver for ads1115, but haven't create a pr due to the incomplete design of adc system. How about that we firstly work out the poorly designed adc part?

@SalimTerryLi are you able to join the weekly dev call to discuss?

I' m able to join next week but with poor English speaking ability. Maybe there is some challenges for me :)

[bys1123]

@SalimTerryLi I'm asking Jinger to help you.

[mrpollo]

@SalimTerryLi please join the hardware channel on Slack and ping us (@dagar @mrpollo)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

[dagar]

We have an adis1115 driver in master.

PX4-Autopilot/src/drivers/adc/ads1115/ADS1115.h

Lines 99 to 105 in cef3d36

	* This driver configure ADS1115 into 4 channels with gnd as baseline.
	* Start each sample cycle by setting sample channel.
	* PGA set to 6.144V
	* SPS set to 256
	* Valid output ranges from 0 to 32767 on each channel.
	*/
	class ADS1115 : public device::I2C, public I2CSPIDriver<ADS1115>