Electronic – Minimal ARM (low-power) circuit design

armlow-powermicrocontrollerpower

I know there are tons of these questions here, and I looked at them, but I still feel unsure about some things.

I've never designed anything using a MCU – for this one I mostly followed the recommended circuits from datasheets. My main question is about the power distribution – sometimes people use many caps, sometimes none, why? Why is the ground supposed to be on VSS pins decoupled with a cap to VDD(+3V3)?

It costs 100$ to buy and ship some of the parts to my country, and I can't risk it… so if you catch anything else wrong please tell me.

My schematic

Best Answer

There is few unclear point to me :

  • There is no pull up resistor on the SPI bus line. I know it's not mandatory but some chip require it.
  • 3.3v is connected to VSS through capacitor C9? (It may not be a mistake but I'm curious)

A little advice when you edit a schematic : try to keep GND head down and input voltage head up (the arrow to the top). It make the schematic clearer

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