General Guidelines for Hardware Design

Architecture is a big topic. The purpose here is not to cover the entire topic. Want to point it out that it pays to begin with interface and connector choices.

1. Begin with a power tree that include voltage/current requirements.
2. Keep power sequence in mind for both turn-on and turn-off.
   1. most of the digital ICs don't like to be back biased meaning voltage on any of its pins goes beyond VCC. This can happen during power-on when VCC is low.
3. Reverse plug-in protection can be a user friendly feature if the power comes from external.

1. Similar to power, please consider which IC needs to come up first by releasing reset in a specific sequence.
2. It is also necessary to hold the reset until VCC stabilizes if the IC does not have built-in power-on reset feature (most modern ICs have POR).

1. Clock tree is a common design document (just like power tree) to document how the clock is generated and distributed.

1. Have clear mind how to program and debug the circuit. JTAG is standard but can be complicated and requires expensive debugger.
2. DEBUG UART can be much simpler for small MCUs.
3. It is also common to have two wire proprietary debug interfaces. Consider referencing to EVK how programming/debug is implemented. It is also a cheap way to use EVK debug feature to program/debug your own design without having to purchase a separate debugger.
4. It is very helpful to have LEDs to show visual sign of life. E.g. to indicate power is up, or to indicate a GPIO can wiggle.
5. The general bring-up procedure is to check Power, Reset & Clock.

1. MCU power consumption is very much dependent on the program that is running. Characterizing power consumption is a career by itself.
2. It can be very handy to have instruments built-in to measure power rail voltage/current.

1. Don't forget to have ESD protection elements for external accessible interfaces.

1. Good layout
2. Filtering
3. Shielding