BBleo? where to discuss?

[Tazling]

I don't see a topic for BBleo on this forum. I had a question about my first one, and was wondering where I should ask it. I find the doco a bit scarce... maybe too high-level for a non-EE like me?

I'll dare to ask my Q here, and maybe a moderator can move it if I'm in the wrong place.

I have been having difficulty getting i2c to work on my first BBleo. It's not my first experience with i2c, actually I've used i2c devices successfully in my main project -- even have 2 Leonardos happily exchanging data over i2c. So I'm not expert at an EE level, but I have learned how to use the relevant libraries, and I've used a logic analyzer to spy on the bus traffic, etc.

Anyway, I was trying to get a simple i2c device working with a BBleo installed on a classic breadboard. The BBleo works at a basic level, can load sketches, blink LEDs and so on. But I can't get it to run an i2c tiny OLED device. Same device works fine on a stock Leonardo with the same sketch, but device init hangs forever on the BBleo. Hmmm.

I ordered a 2nd BBleo and will assemble it and compare, but I fear there's some possibility that I might have damaged the first one. I'm not quite clear on its relationship with the breadboard gnd and vdc rails; I thought at first that it was to be powered from the breadboard (i.e. the rail as an alternative VIN), so I plugged it into a bboard that had its own power supply already. So the 5vdc rail was hot and the BBleo was USB powered.

When my i2c device didn't work on the first try, I removed the power supply and discovered that the BBleo lit up on USB power alone, and even tried to power the rail itself. Yet I'm not seeing power on the i2c bus when I attach my OLED breakout.

Now I'm wondering whether I may have damaged some p/s component on the board by attaching it to a live power rail, so that it can now no longer handle the load of the OLED device. Haven't yet had time to poke about with a scope to see how sda and scl look -- need a quiet evening for that -- but thought that in the meantime more experienced BBleo users might be able to tell me:

a) is the BBleo supposed to power the bboard rail, or be powered by it?
b) if the rail is live and the BBleo has only a USB connection, does the rail act as a normal VIN or is that a problem?
c) if the rail is live and the BBleo has a wall wart connected (i.e. 2 VIN sources) is that bad?
d) if I have damaged something on my BBleo board, is there hope of repair? or should I just fuhgeddaboudit and assemble another one?

[oz]

Tazling,

There is a schematic of the board on Github - but you could be forgiven if you are confused by it - EagleCad schematics are often somewhat confusing as to the headers.

a) is the BBleo supposed to power the bboard rail, or be powered by it?

Power it - for use in sensors

b) if the rail is live and the BBleo has only a USB connection, does the rail act as a normal VIN or is that a problem?

The I2C rail can act as a (5 volt) VIN - it's not a problem when supplied by 5 volts. If supplied at a lower voltage, then USB will want to bring the line up to 5 volts. The USB line is protected by a polyfuse that will trip over about 500 mA, with the polyfuse going into a high resistance state.

c) if the rail is live and the BBleo has a wall wart connected (i.e. 2 VIN sources) is that bad?

There is a voltage regulator on the External IN jack that protects the board from over voltage. It will reduce a 6 volt or greater voltage to 5 volts. If 5 volts is supplied to the external jack, the voltage at the 5 volt line will appear to be about 4.8 volts (which also depends on the current draw).

d) if I have damaged something on my BBleo board, is there hope of repair? or should I just fuhgeddaboudit and assemble another one?

Does the board still upload sketches? If it does then probably the board is fine, and the issue is something in some software or hardware difference between the two boards. One issue with the Arduino Leonardo that has caused no end to grief over the years is the way they allowed the board to be switched between modem and keyboard in software. The boards can get themselves into the wrong state and need to have their firmware reflashed to recover them. Our Leonardo, which uses the Arduino firmware also can have the same problems.

If you want to send the board back to the shop we'll reflash it and send it back to you. You have to pay the shipping to use but we'll send it back for free.