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20261023-1233-key-box-adc-voltage-inputs Key Box 36: dedicated ADC and a 0-10 V mode for the eight analog inputs

  • status: completed
  • priority: P1
  • owner: claude/key-box-adc-1233
  • createdAt: 2026-10-23 12:33

Description

章节标题：“Description”

The eight Key Box 36 analog inputs read 0-190 Ohm or 4-20 mA through the TIC12400 ADC (0-6 V, leakage up to +-110 uA). The owner asked for 0-10 V sensors and chose option B on 2026-10-23 ("用方案B"): a dedicated SPI ADC, a divider per channel and a switchable pull-up, so each channel is Ohm, mA or voltage by software.

Acceptance:

  • AIN1-AIN8 read by an 8-channel 12-bit SPI ADC (ADS7038, AVDD = filtered +5V, CS on IO11); each channel Ohm (switchable 1k pull-up), 4-20 mA (100 R shunt) or 0-10 V (pull-up and shunt off, 50 k input); all channels high impedance while DO_EN is low.
  • A 32 V short on any AIN in any mode does not damage the board.
  • Schematic ERC 0; PCB DRC 0 unconnected / clearance / short; spec, design appendix, guide, brief and the key-box README follow.

ActiveForm

章节标题：“ActiveForm”

Adding a dedicated ADC and a voltage mode to the Key Box analog inputs

Dependencies

章节标题：“Dependencies”
  • blocked by: (none)
  • blocks: (none)

Notes

章节标题：“Notes”