MCP3201 not talking to ESP32-S3

[robzy]

I've spent hours trying to debug this but can't solve it.

I have an MCP3201 connected to an ESP32-S3 (SuperMini on AliExpress) on a custom PCB. JLCPCB made and assembled the PCB.

Problem: The MCP3201 refuses to actually send out any data on its DOUT pin. It has an SPI-like interface with a CS, CLK, and DOUT/MISO signal.

Connections: I have connected the GPIO8 to DOUT, GPIO9 to CLK, and GPIO10 to CS. For the MCP3201 I've connected Vref to VDD and IN- to GND. Both of these should be valid according to the datasheet.

Software debugging: I have using an MCP3201 Arduino library, the SPI Arduino library, and even raw bitbanging to the MCP3201, and still nothing.

Hardware debugging: I have used a logic analyser to maake sure that the CS and CLK signals are coming through as expected. And I have confirmed the MCP3201 is getting 3.3V. I've double checked that the IC is an MCP3201 and that it's in the correct orientation.

Possibly a clue: When the ESP32-S3 SuperMini board itself is unplugged from the PCB the GPIO8 pin remains at ground regardless of whether I touch GPIO8 or not. When the ESP32-S3 SuperMini board is plugged into the PCB the GPIO8/DOUT pin seems to be semi-floating, because when I touch the pins the firmware reads different values.

Any ideas about next steps? I'm grasping at straws, but is it possible that JLCPCB accidentally sourced fake MCP3201s? <-- I was totally wrong

[JLCPCB Official]

hello , we purchase parts only from original manufacturers, their authorized distributors, or reliable suppliers.We want to assure you that the quality is of utmost importance to us.
Every single part for assembly from JLCPCB is guaranteed to be authentic and traceable to the original manufacturer.  For any problem, you can also contact  support@jlcpcb.com ~

[robzy]

I am sorry. I shouldn't have said that without thinking.

I should say that I've made dozens of orders with JLCPCB, including assembly services, and I've always had a good experience.

I did some more investigation on my board - revised my bitbanging code - and now the MCP3201 is working perfectly. More investigation needs to be done to work out why the other code isn't working - but I've now proved 100% that the MCP3201 is working perfectly.