MCP3KADC(4)

📦 version 11.0, in nixpkgs unstable

💅 MCP3KADC(4) — bestie's guide to the Microchip 3x0x SAR ADC

okay so this is mcp3kadc(4), from the Kernel Interfaces Manual, section 4. it's giving "tiny chip, big voltage-reporting energy" and honestly? we're obsessed. let's get into it ✨

🌸 NAME 🌸

mcp3kadc — the Microchip 3x0x SAR analog to digital converter. yes bestie, it reads voltages. it's literally the vibe translator between "analog world" and "numbers your computer understands" 🦋

🎀 SYNOPSIS 🎀

mcp3kadc* at spi? slave ? flags N

that's the whole config line. at spi? (hangs off SPI), slave ? (its slave number), and flags N — and the N is doing a LOT of work, so keep reading 👀

✨ DESCRIPTION ✨

the mcp3kadc driver reports the current voltage on the chip's ADC channels through the envsys(4) API. and it doesn't just blindly spit numbers — it calculates these values according to the currently selected reference voltage (Vref). so like, the math is mathing 🧮💖

Vref is changeable through the sysctl(8) node hw.mcp3kadc0.vref. slay.

here's the part you actually need, bestie — the supported chips. the type of chip gets selected with the flags argument in the config file. no cap, this table is the whole personality of the driver:

  • MCP3001 — Resolution: 10 bits · Input Channels: 1 · flags: 0
  • MCP3002 — Resolution: 10 bits · Input Channels: 2 · flags: 1
  • MCP3004 — Resolution: 10 bits · Input Channels: 4 · flags: 2
  • MCP3008 — Resolution: 10 bits · Input Channels: 8 · flags: 3
  • MCP3201 — Resolution: 12 bits · Input Channels: 1 · flags: 4
  • MCP3202 — Resolution: 12 bits · Input Channels: 2 · flags: 5
  • MCP3204 — Resolution: 12 bits · Input Channels: 4 · flags: 6
  • MCP3208 — Resolution: 12 bits · Input Channels: 8 · flags: 7
  • MCP3301 — Resolution: 13 bits · Input Channels: 1 · flags: 8
  • MCP3302 — Resolution: 13 bits · Input Channels: 4 · flags: 9
  • MCP3304 — Resolution: 13 bits · Input Channels: 8 · flags: 10

like, pick your fighter. more channels = more to love 💅

👑 SYSCTL VARIABLES 👑

the following sysctl(3) variables are provided:

  • hw.mcp3kadc0.vref — defines the reference voltage on the chip's Vref pin in millivolts (mV). it defaults to the ADC's maximum output value + 1 in millivolts (e.g., 4096 for a 12-bit ADC).

so yeah, that default is the "max value plus one" situation — like 4096 when you're running a 12-bit ADC. iconic little detail, don't lose it ✨

🦋 SEE ALSO 🦋

(the friend group 💖 go read them, iykyk)

🌈 HISTORY 🌈

the mcp3kadc driver first appeared in NetBSD 8.0. a legend was born 🎀

💜 AUTHORS 💜

the mcp3kadc driver was written by Frank Wille. thank you frank, we love you for this 🫶👑

🍓 reminder bestie: this page is from Debian, dated August 18, 2015 — that's the source/version and date energy right there. anyway ily, go read your voltages responsibly 💀✨
📦 where this page comes from