Thanks for picking out all the docs.
Seemingly the Schmitt-trigger buffer is only active on the chip for pins set as input and the way pin 1.4 is used as an electrode can't use it.
Towards providing something similar in the code. I added some trigger threshold variables; SEQUENCED_TRIGGERS_INDICATING_LANDING and SEQUENCED_TRIGGERS_INDICATING_ABSCENCE.
The while loop firstly does a sample on the electrode and then does the led blinking in line, and to provide the blinking there’s a 2 second sleep. So if I set SEQUENCED_TRIGGERS_INDICATING_LANDING to 4 consecutive triggers then it takes 8 seconds to determine the presence of flying gizmo. Actually, even with this, with the chip on the pcb still get the odd false result.
There may be some mileage though in reducing the sleep time and increasing the consecutive trigger threshold – will play around with that later.
Unfortunately need to have DIL sockets in place as I’m frequently pulling the chip off and changing the code to adapt, but can see how easily such things as the sockets can play a part. I found that on the pcb the board and even the batteries become proximity sensors, so if your put your hand within a few millimeters of the batteries - it triggers.
Good point about the Led’s potentially being an issue, so tried ruling that one out by connecting a resistor and led in place of each led ring; didn’t though make a difference.
Tried moving the chip onto a separate solderless breadboard and jumpering over to the first pcb board (I had originally put pins on that pcb so the Launchpad could connect easily) to use the transistors and led connectors on it. No improvement and possibly worse because of all the increased copper area.
Finally tried using the launch pad with battery power. I was running short on jumper cables and used the solderless breadboard as a join point. It was a lot better but using the breadboard I think introduced the odd false result.
Balancing things with not wanting to add any more IC components (cost) or create a custom pcb and rapidly approaching Xmas (only just started to look at the other landing pads and associated ‘bling’) have opted as fall back to order another Launchpad and for the meantime just sense take off and landing on two of the landing pads.
Still want to get this working though on the pcb alone. You mentioned ‘decoupling – or bypass –‘ which looks worth trying. I’m presuming this involves capacitors between ground and whatever is outputting positive, so would I have this attempt covered if I put capacitors in the following places :
Between positive and negative as it comes onto the pcb.
Between negative and each output pin used for switching the led feeding transistors.
Between negative and positive take off pins for led rings.
Any other places worth putting capacitors on?