Every signal on NanoSoC crosses the same boundary: core logic, a pad cell, a bond wire, the package, the board. The pad cell is where the integrator's choices live — what kind of cell, what it drives, what holds it while the chip is in reset — and those choices are made per pin in a table, never by accident in a netlist. This topic builds that table: the three pad families, the ring that arranges 31 pads around the die, and the function, pull and drive options inside each cell. Its companions in this section count the pads, place them on balls, feed them power and protect them; the physical construction of the ring belongs to the physical design course.
Lesson | After it you can... |
|---|---|
List every NanoSoC pad by family and say why each signal takes its type. | |
Read the 8, 8, 8 and 7 pad ring and check that each side carries supplies and the crystal stays quiet. | |
Choose pull and drive per pin and check the reset-state table, including the pad cell's own power-on control. |
Suggested order: top to bottom. Types first, because the ring is arranged around which pads need which supplies; then the ring; then the per-pin options, which assume both. The pad-count topic next door consumes the inventory the first lesson produces.
Because the ballout assigns every pad: each signal pad needs a ball with a routable escape, each supply pad needs a ball close to the pad that feeds the die, and analog pads need quiet neighbours. Without the inventory there is nothing to assign.