🔌 Embedded · Electronics
What stays equal vs what divides
Circuit basics (#1–6)
Kirchhoff's laws (KVL · KCL)
KVLKCLwiki/embedded-kvl-kcl
TL;DR
KCL (currents into a node sum to currents out) and KVL (voltages around a loop sum to zero) are the two conservation laws that let you compute current and voltage distribution in multi-component circuits.
Two conservation laws
- KCL: 5A into a node leaves as 2A + 3A — water at a fork neither appears nor vanishes.
- KVL: +12V − 5V − 7V = 0 in a series loop — supplied voltage is fully consumed, the direct basis of voltage drop.
Series vs parallel
- Series: same I everywhere, voltage divides — compute with KVL.
- Parallel: same V everywhere, current divides — compute with KCL.
| Series | Parallel | |
|---|---|---|
| Equal everywhere | Current I | Voltage V |
| Divides | Voltage V | Current I |
| Tool | KVL | KCL |
Kickboard / STM32 context
- KCL: battery-to-3-phase (U/V/W) current split and shunt current measurement.
- KVL: gate driver + MOSFET + coil voltages sum to the supply voltage.
Pitfalls & gotchas
The trap is sign convention — pick consistent voltage/current directions or every sign in the calculation flips.