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V3 Fail -- DO NOT BUILD

A project log for Wireless BLE Kinesis Advantage (Custom Controller)

Replaces the stock controller with an nRF52 BLE SOC and MCP23S17 io expander. BLE Kinesis with great (few months) battery life.

mike-wMike W 10/27/2018 at 12:437 Comments

Ok, just noticed the board was draining unusually fast. A quick multimeter check revealed it was drawing 10mA. What?!

I suspect it's to do with using the TX/RX pins to drive LED(s) which in turn prevents the CP2104 Serial chip from sleeping. That chip has a quiescent current of about 7mA so that roughly adds up to the 10mA we're seeing.

I'm currently considering my options.

a) Re-wire the two led(s) to 2 of the pins currently used by the RGB push button.  We'll lose yellow and green colors, but at least we can still indicate charging status by flashing the LED(s) and still use them as a battery level indicator.

c) See if we can fix this via firmware. ie. only setting pin to output mode just before we need to light up a LED. My multimeter broke so will be a few days until I can verify this works.

I also tried Charlieplexing to drive 4 LEDS with 3 pins but that doesn't work since we're delaying the board at the end of the loop to sleep.

Discussions

Mike W wrote 10/27/2018 at 23:51 point

Yeah and I thought I was finally done. Btw I soldered a whole board before I found out the case won't close if you used headers (even the shorter ones). 

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n0tso wrote 10/28/2018 at 20:20 point

Haha, thanks for the feedback. I was eyeballing it and feeling nervous.

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Mike W wrote 10/28/2018 at 20:25 point

yeah, it's all or nothing over here. I must be on my 5th feather or something. Are you doing the whole build, even with the RGB button?

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n0tso wrote 10/28/2018 at 20:50 point

No, thanks to your quick updates I'm going to order the v4. The power consumption is great, and I wasn't looking to add the button even with th v2. I'll build out the v4 and let you know how it goes.

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Mike W wrote 10/29/2018 at 13:27 point

if you wait another day I can confirm v4 numbers when my meter gets fixed.

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n0tso wrote 10/29/2018 at 18:02 point

sgtm (sorry, hackaday.io won't let me reply more than two deep)

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n0tso wrote 10/27/2018 at 23:45 point

That's a shame. 

Been following the project (but not close enough apparently ;), and just got my V2 from OSH Park this weekend. Oh well. At least I settled the "should I use female headers for the NRF52 feather" question :)

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