MainBoard DF v8 —

Platform: STM32G431CBTx (ARM Cortex-M4, 170 MHz)
Machine: Draw Frame (DF)
Motors: 3 — Front Roller (FR), Back Roller (BR), Creel
IDE: STM32CubeIDE | CAN: FDCAN1 @ 1 Mbit/s | BT: USART1 @ 115,200 bps

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How It Works

Overview

The MainBoard DF v8 is the master controller for a textile Draw Frame machine. It calculates motor RPM targets from operator settings, commands 3 motor drives over CAN, monitors sensors, and communicates machine status to a mobile app over Bluetooth.

  [App] <──BT──> [MainBoard STM32] <──CAN──> [FR Motor Drive]
                                   <──CAN──> [BR Motor Drive]
                                   <──CAN──> [Creel Motor Drive]
                   │
                   ├── EEPROM (settings)
                   ├── MCP23017 (sensors + tower lamp)
                   └── USART2 (debug log)

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Startup Sequence

1. EEPROM is read → settings loaded into msp struct
2. Settings validated → defaults loaded if invalid
3. CalculateMachineParameters() derives RPM targets for all 3 motors
4. State machine enters IDLE_STATE
5. Amber tower lamp turns ON — machine ready

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State Machine

The firmware runs a state machine. Each state has its own while(1) loop and exits only on a transition event.

State	What Happens
IDLE_STATE	Waiting for input. Yellow = inch jog. Green = start run.
RUN_STATE	All 3 motors running. Monitors sensors, length counter, pause/stop events.
FINISHED_STATE	Target output length reached. Motors ramp down.
ERROR_STATE	Fault active. SMPS cut. Red lamp ON. Red button to recover.
SETTINGS_STATE	Receives new settings from app. Returns to calling state.
DIAGNOSTICS_STATE	Single-motor test run from app.
DEBUG_STATE	Manual motor commands via BT console.

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Motor Control Flow

Settings from EEPROM → CalculateMachineParameters() → RPM targets sent over CAN

delivery_mMin  ──→  FR_MotorRPM    (FR circumference + gear ratio 1.0)
draft ratio    ──→  BR_MotorRPM    (FR speed ÷ draft × gear ratio 3.07)
creelFactor    ──→  Creel_MotorRPM (creel pulley ratio 0.722 × tensionFactor)

CAN commands issued to drives:

Command	Effect
START	Ramp up to target RPM
RAMPDOWN_STOP	Controlled deceleration to stop
EMERGENCY_STOP	Immediate cut — no ramp
CHANGE_RPM	Update speed while running
RESUME	Resume from paused
RESET	Clear motor fault

After every multi-motor command, TIM17 (15 ms) waits for ACK frames from all drives. Missing ACK → SYS_ACK_ERROR → ERROR_STATE.

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Sensors

Sensor	Interface	Action on Trigger
Creel sliver cut	MCP23017 (I2C GPIO expander)	Pause machine, notify app BT_PAUSE_CREEL_SLIVER_CUT
Lapping sensor	MCP23017	Pause machine, notify app BT_PAUSE_LAPPING

Both sensors use software hysteresis (100 ms TIM7 ticks) to avoid false triggers. Active only when rotary switch is ON during RUN_STATE.

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Bluetooth Communication

Framed TLV protocol over USART1. Frame delimiter: 0x7E.

Key message flows:

App ──[0x01 SETTINGS_FROM_APP]──→ MC    Send new delivery speed / draft / length etc.
App ←─[0x06 MC_STATE]────────── MC     Machine status every 500 ms
App ──[0x04 DIAGNOSTICS]────────→ MC    Test a motor drive
App ──[0x0A RESET_LENGTH]───────→ MC    Reset output length counter
App ──[0x0F PID_NEW_VALS]───────→ MC    Write PID gains to a motor drive

Settings are stored in EEPROM immediately on receipt. Motor RPMs are recalculated on every settings change.

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EEPROM Settings

Parameter	Address	Default
delivery_mMin	0x02	80 m/min
draft	0x06	8.0
lengthLimit_m	0x0A	100 m
rampUpTime	0x0C	6 s
rampDownTime	0x0E	6 s
creelTensionFactor	0x12	1.0

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Error Handling

Any module sets ME.ErrorFlag = 1 and calls ME_addErrors(). The active state detects this and transitions to ERROR_STATE.

Error	Code	Source
CAN bus lost to a motor	98	System
ACK timeout (15 ms)	97	System
SMPS feedback lost	96	System
Motor over-current/voltage/temp	1–7	Motor drive (CAN)
EEPROM read/write failure	8–9	System

On error: SMPS cut → Red lamp → BT stop broadcast every 500 ms → Red button to recover.

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CAN Health Monitor (SysObserver)

TIM16 fires every 1 s. For each active motor, checks if new CAN frames were received since last tick. No frames → SYS_CAN_CUT_ERROR. Observers enabled only while motors are running.

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Tower Lamp & Buttons

State	Lamp
IDLE	Amber ON
RUN	Green ON
PAUSED	Amber ON
FINISHED	Red + Green + Amber ON
ERROR	Red ON
Stop/complete	Buzzer 1 s

Button	Function
RED	Emergency stop / exit IDLE / clear ERROR
GREEN	Start run / resume after pause
YELLOW	Manual pause / inch jog in IDLE
ROTARY SW	Enable/disable sliver sensor monitoring

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Timers Quick Reference

Timer	Period	Purpose
TIM7	100 ms	BT status TX (5 ticks = 500 ms), sensor monitor, length counter
TIM16	1 s	CAN health check
TIM17	15 ms one-shot	ACK timeout after motor command
TIM15	250 ms	Diagnostic data stream to app

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Build & Flash

# Build in STM32CubeIDE
File → Import → Existing Projects into Workspace
Build Config: Release
Ctrl+B → Output: Release/MainBoard_DF_v8.elf

# Flash via STM32CubeProgrammer
Load: MainBoard_DF_v8.elf  →  Program & Verify

Debug UART: USART2 @ 2,000,000 bps — connect serial monitor to view logs.

⚠️ Do not regenerate the .ioc file without engineering review.