Hi everyone,

I am working on a wearable ECG monitoring device and would appreciate some feedback on my schematic before I proceed to the PCB layout.

Project Overview:

• MCU: Seeed Studio XIAO nRF52840.
• Analog Front-End: MAX30003 (Biopotential AFE).
• Power: The system uses the 3.3V rail from the XIAO, which is stepped down to 1.8V via an AP2112K LDO to power the MAX30003.
• Level Shifting: Since the MCU operates at 3.3V and the AFE at 1.8V, I’ve implemented a TXS0108E bidirectional level shifter for the SPI bus and interrupt pins.
• Storage: W25Q128 Flash Memory for data logging.
• Clock: External 32.768kHz oscillator (SiT1533) for the MAX30003.

Is there anything wrong in my schematic and how can I improve it. It makes me so nervous. Thank you all.

 

1) Ground symbols always vertical- NEVER sideways or upside-down.
2) Just using NET labels might make a PCB design program happy- but it does nothing for schematic readability.

The job of a schematic is to make the design understandable, make this a priority.


Arrange the drawing so the general signal flow is top-to-bottom, left-to-right.
Draw the connections so the eye can see and follow the signal flow, rather than forcing a reader to hunt for matching signal names.
Use net labels where it makes sense- but not as primary connectivity.

When I see a schematic like this- I don't feel like reading it, it's too much work, so I skip it- and that would be your loss.

 

thanks sir , here is my schematic