Pin-out
Pin 1 will be the leftmost pin in a row, pin numbers will be based on cavity, ie. NC cavities count as a pin as well.
Each row of pins corresponds to one stalk
The top-most L shaped group above is a passthrough that’s not connected
Turn Signal
Top group in image, pins 1 and 6 are for left/right turn:
No turn - open
Right turn - 0.7kR
Left turn - 2.2kR
Cruise Control
Bottom group in image, pins 2 and 3 are for speed change, pins 6 and 7 are for set button
Speed up - 10.6kR
Slow down - 9.1kR
Neither - 16.7kR
Set button is a NO switch
Some other pin combinations for bottom group also show some resistances
stalk position “back” = stalk pushed away from the driver
Pin Combination | Resistance (kR) | Stalk position |
|---|---|---|
1 & 4 | 0.20 | All positions |
2 & 7 | 8.38 | Neutral |
2.20 | Up (Speed Up) | |
2.20 | Up + Set Button | |
0.69 | Down (Speed Down) | |
0.69 | Down + Set Button | |
8.38 | Back | |
3 & 7 | 8.4 | Neutral |
List of proposed changes:
Surge protection - this board will be prone to ESD due to frequent interaction.
Surge Protection Research:
What is Surge Protection/ESD?
Electrostatic Discharge (ESD) can be caused by a seemingly random surge in Voltage due to static electricity or electrostatic induction. Since the driver interacts with the controls a lot, there is a chance for ESD to occur from static electricity. Due to the random voltage spike, microcontroller pins can easily get damaged, so surge protection is required.
Best Practices:
Keep sensitive components away from high voltage components
Short routes/wires
short wires = less inductance = less EMI = less ESD
Ground Plane in PCB stackup
can accept ESD-induced currents
Do not run wires parallel to any wire through which ESD pulses might travel (due to EMI inducing voltages in other wires)
Potential Fixes:
Transient voltage suppressor (TVS) diodes (or Zener diodes)
Unidirectional - good if the polarity of an ESD event is known with respect to the system I/O
Bidirectional - good if the polarity of an ESD event is unknown with respect to the system I/O
Weakness: Transient oscillations can cause TVS diodes to fail
ESD suppressors
generally use TVS diodes
ex. https://www.digikey.ca/en/ptm/c/comchip-technology/esd-and-esd-suppressors
Reverse bias diodes for clamping voltages
Example Circuit to Avoid ESD
The TVS diodes ensure that the voltage surge is regulated
The resistor is used to limit the current (protecting the diodes from ESD failure)
Readings
https://www.digikey.ca/en/articles/protecting-inputs-in-digital-electronics
https://resources.altium.com/p/beginners-guide-esd-protection-circuit-design-pcbs
https://industrial.panasonic.com/ww/ss/technical/n2
Driver Display(s)
per regulations, commercially available electronic panel meters with internal batteries do not need to be powered by the main battery pack. These displays can be used to our advantage to save more power from the main battery pack.