Configure, check and test all 3 I2C buses on EM2

[RobertK66]

• Enable all 4 sidepanel I2C buses and configre them (to use 100kHz at this time)
• write testcode to address external slaves

also see discussions here: #23

[kodsurf]

With a code commit :

https://github.com/RobertK66/obc_1769_core/commit/6231abd36073e861503235f9ec31631412e3558e

I am able to transmit message over I2C from OBC to Arduino

Amount of bytes received by arduino is always correct (when changing "read_request" length)

However received bytes are wrong.

[kodsurf]

During initialization of LPC_I2C

I enabled switches

which should activate LPC_I2C2 on A and B sides

Then I checked pinning_climb.h

All those switches are by default initialized with HIGH value.

Meaning that all switches are enabled by default ?

However the strange thing that I noticed :

If I manually set those switches to LOW - I2C still works (with wrong bytes)

[RobertK66]

Maybe the clock pulses are not compleetly 'cut off' by the Switch ICs!?

Primary goal of this EN pins is to get rid of short circuited pins in SP connectors. I am not sure, why you see your behaviour. Maybe we have to define a better test case for this "saftey feature". To make funvtional tests just have all EN pins initilaized to High and connect to any of the buses.....

Remark: You can easily test all Enable Pins with my hw_check command:

| 'h' | \<pinIdx> \<mode> | sets an GPIO pin to mode (0: initVal, 1: high, 2: low, 3: slow blink, 4: fast osz.)  |

The Pin Idx for the 4 I2C EN pins are:

PINIDX_I2C_A_EN  31
PINIDX_I2C_D_EN  32
PINIDX_I2C_C_EN  33
PINIDX_I2C_B_EN  42

[kodsurf]

After latest remark regarding enabling C/D in pinning_climbobc.h :

I2C works correctly on every sidepanel.

Switches also work as expected.