I have checked with multimeter that the two GND pins in the micro-controller was around 1 ohms . Please somebody tell
1) what is the need of two GND or more GND pins if they are shorted internally
2) The resistance between the GND pin is around 1 ohms , why
3) whether this pin can be used to provide GND to other side of the circuit
Can be lots of reasons depending on the micro controller:
-analogue ground and digital ground for seperating the supplies
-bonding wire can handle lets say 100mA and the microcontroller has to be able to sink on all GPIO pins a total of 200mA (fill in any value you like)
-layout of the silicon, two groundwires easier layout (for instance power for the core and power for peripherals) or lower impedance.
and lots more,
two is not much, there are plenty of chips (like fpga's) that have more then ten ground connections and different power pins.
1 ohm is not a short. They quite simply probably decided they needed lower than 1 ohm to ground. You need a lower ground resistance to help avoid
ground bounce.
Each and every GND pin must be connected to the ground on the PCB with a low impedance path for proper operation. Same goes for VCC. And you need separate decoupling. And it is not a jumper. Unless you design a time bomb.
For high speed digital circuits, it is necessary (ground bouncing and stuff) to have a GND and VCC every 8-10-20 digital output, just to have proper slew rates.
For high speed digital circuits, it is necessary (ground bouncing and stuff) to have a GND and VCC every 8-10-20 digital output, just to have proper slew rates.
It would also be required to provide low impedance returns for EMI purposes.