abse/smart-ring-flex

src/component-notes.ts

// Shown as schematic text on the same sheet as each referenced component.
export const componentPurpose:Record<string,string> = {
 R22:"Pull-up for the dedicated optical I2C data.",
 U1:'BLE microcontroller: reads sensors and sends data.',
 U2:'Programmable cell charger and system power-path controller.',
 U3:'Dual-detector optical AFE; green/red/IR acquisition.'
 ,LED1:'Green, red and IR emitters: illuminate finger tissue.'
 ,PD1:'Photodiode 1: first spatial optical measurement path.'
 ,PD2:'Photodiode 2: second spatial optical measurement path.'
 ,C27:'Analog supply reservoir for optical AFE.',
 U4:'Temperature sensor: measures local skin-side heat.',
 U5:'LIS2DW12 accelerometer: movement samples and wake interrupt; MCU counts steps.',
 U6:'Cell protection: detects voltage/current faults.',
 U7:'Low-power regulator: supplies 1.8 V logic.',
 U9:'Dual MOSFET: disconnects the cell on a fault.',
 Y1:'32 MHz crystal: accurate clock for BLE radio.',
 ANT1:'2.4 GHz antenna: sends and receives BLE RF.',
 L1:'RF matching inductor: matches MCU to antenna.',
 R1:'Pull-up: keeps charging off until MCU verifies safe limits.',
 R2:'Thermistor shunt: adds margin below 45 C charge limit.',
 R6:'Filters the battery protector voltage input.',
 R7:'Limits current into protector sense input.',
 R8:'Sense resistance: lowers overcurrent trip level.',
 R12:'SCL pull-up: holds I2C clock high when idle.',
 R13:'SDA pull-up: holds I2C data high when idle.',
 R15:'RESET pull-up: holds the MCU out of reset.',
 R17:'Upper divider resistor: scales battery voltage.',
 R18:'Lower divider resistor: scales battery voltage.',
 R19:'Zero-ohm link: allows antenna matching changes.',
 C1:'Input bypass: smooths charging-dock power.',
 C2:'System reservoir: smooths the VSYS supply.',
 C3:'Battery bypass: stabilizes charger BAT node.',
 C5:'Protector bypass: filters measured cell voltage.',
 C6:'LDO input bypass: smooths system supply.',
 C7:'LDO output bypass: stabilizes 1.8 V supply.',
 C8:'ADC filter: smooths battery-voltage reading.',
 C9:'DEC1 bypass: stabilizes internal MCU supply.',
 C10:'DEC3 bypass: stabilizes internal MCU supply.',
 C11:'DEC4 bypass: stabilizes internal MCU supply.',
 C12:'MCU supply bypass: shunts fast supply noise.',
 C13:'MCU supply bypass: shunts fast supply noise.',
 C14:'MCU supply bypass: shunts fast supply noise.',
 C15:'MCU bulk bypass: supports supply transients.',
 C16:'Crystal load capacitor: sets clock loading.',
 C17:'Crystal load capacitor: sets clock loading.',
 C18:'RF shunt capacitor: tunes antenna matching.',
 C21:'Optical logic bypass: filters 1.8 V noise.',
 C22:'Reference bypass: stabilizes optical ADC reference.',
 C23:'LED reservoir: supplies optical LED pulses.',
 C24:'Accelerometer VDDIO bypass: filters I/O supply.',
 C28:'ST motion supply bypass: local100nF decoupling.',
 C29:'ST motion local bulk:10uF rail reservoir.',
 C25:'Accelerometer VDD bypass: filters core supply.',
 C26:'Temperature sensor bypass: filters its supply.',
 TP1:'Dock contact: receives regulated 5 V charging.',
 TP2:'1mm ground test pad; J401 provides the detachable exterior charging connection.',
 TP3:'Bottom SWD data pad: 1.8 V signals only.',
 TP4:'Bottom SWD clock pad: 1.8 V signals only.',
 TP5:'P0.21/reset pad: enable reset in UICR.',
 TP6:'Target 1.8 V reference: not a 3.3 V input.',
 TP7:'Bottom debug ground pad: probe return.',
 TP8:'Cell-positive pad: connects separate battery.',
 TP9:'Cell-negative pad: connects separate battery.',
 TP10:'Battery NTC pad: senses charging temperature.',
 TP11:'NTC return pad: temperature-sensor ground.'
,
 R20:"Switches bias for the separate cell-temperature probe.",
 TP12:"Connects the cell-temperature probe to the MCU ADC."
}