Rework wiring diagram for single-pole KCD11 switch

WIRING-DIAGRAM.md

@@ -0,0 +1,247 @@
+# Battery-Powered 28BYJ-48 Stepper Controller
+
+This project uses one 18650 cell, a TP4056 charger module, an MT3608 boost
+converter, an Arduino Nano, and a ULN2003 driver board to power a 28BYJ-48
+stepper motor.
+
+A single-pole KCD11 rocker switch turns the battery-to-boost path on and off.
+Turning the switch off removes the boost input, so the whole 5 V rail (Nano and
+motor) is unpowered. The Arduino Nano clone used here has **no USB VBUS Schottky
+diode**, so the USB and battery-powered 5 V supply must not be connected to the
+Nano at the same time.
+
+> This document describes wiring and power only. It does not include Arduino
+> code.
+
+---
+
+## 1. Components
+
+| Component | Notes |
+|---|---|
+| 18650 Li-ion cell | Single cell, suitable holder or secure battery connection |
+| TP4056 charger module | Use a protected module with separate `B+`, `B−`, `OUT+`, and `OUT−` terminals |
+| MT3608 boost converter | Adjustable; set its output to 5.0 V before connecting the loads |
+| KCD11 rocker switch | Single pole, on/off; see the variant note below |
+| Arduino Nano clone | This clone has no VBUS Schottky diode |
+| 28BYJ-48 stepper motor | Use the 5 V version |
+| ULN2003 driver board | Matches the motor’s 5-pin plug |
+| Optional fuse | Near TP4056 `OUT+`; rated above normal load current and below safe limits of the cell, protection board, and wiring |
+| Optional capacitor | 100–470 µF across the 5 V rail; observe capacitor polarity and voltage rating |
+
+Check the labels on the actual modules: board layouts and terminal names vary.
+Some TP4056 boards do not have a protection circuit or separate `OUT` terminals.
+This diagram requires a protected module with separate load terminals. Do not
+assume an unprotected TP4056 board provides battery over-discharge or
+over-current protection, and do not use its `B+`/`B−` pads as though they were
+protected `OUT+`/`OUT−` pads.
+
+### KCD11 switch variants
+
+The KCD11 family ships in several contact configurations and often shares one
+housing across them. Terminals labeled `1`, `1a`, and `1b` describe a single
+pole with two throws; the unused throw may be molded into the housing with no
+metal lug. This build needs only **one on/off pole with two usable terminals**.
+
+On the switch used here, `1` is the **center lug (common)** and `1b` is the
+populated throw; `1a` is an empty pocket and stays **unconnected**. Wire the two
+switch wires across `1` and `1b`. A mechanical contact has no polarity, so
+either wire may go to either lug.
+
+Confirm the switch with a multimeter before wiring: there should be continuity
+between `1` and `1b` when the rocker is on, and none when it is off. A single
+pole is sufficient because the motor has no independent supply of its own (see
+section 4).
+
+---
+
+## 2. Power flow
+
+```text
+18650 ──► TP4056 protected battery/load terminals
+                     │
+                     └── OUT+ ──► KCD11 ──► MT3608 ──► 5 V rail
+                                                          ├── Nano 5V
+                                                          └── ULN2003 VCC
+```
+
+The TP4056 is a **charger**, not a 5 V power supply. Its `IN+`/`IN−` terminals
+are the USB charging input. The `B+`/`B−` terminals connect to the battery.
+The protected module’s `OUT+`/`OUT−` terminals provide the battery-voltage load
+connection.
+
+The MT3608 boosts the cell voltage (approximately 3.0–4.2 V) to 5.0 V.
+
+---
+
+## 3. Wiring schematic
+
+```text
+Battery:
+  18650 (+) ──► TP4056 B+
+  18650 (−) ──► TP4056 B−
+
+Charging input:
+  USB 5 V (+) ──► TP4056 IN+
+  USB GND     ──► TP4056 IN−
+
+Battery-powered load path:
+  TP4056 OUT+ ──[optional fuse]──► KCD11 terminal 1 (common, center lug)
+  KCD11 terminal 1b ──► MT3608 IN+
+  KCD11 terminal 1a (if present) ──► leave unconnected
+
+  TP4056 OUT− ──► common system GND
+  MT3608 IN−   ──► common system GND
+  MT3608 OUT−  ──► common system GND
+  Nano GND     ──► common system GND
+  ULN2003 GND  ──► common system GND
+
+5 V and motor supply:
+  MT3608 OUT+ ──► 5 V rail ──┬──► Arduino Nano 5V
+                              └──► ULN2003 VCC
+
+Control and motor:
+  Arduino Nano D9  ──► ULN2003 IN1
+  Arduino Nano D10 ──► ULN2003 IN2
+  Arduino Nano D11 ──► ULN2003 IN3
+  Arduino Nano D12 ──► ULN2003 IN4
+
+  28BYJ-48 5-pin plug ──► ULN2003 motor connector
+```
+
+### Important TP4056 ground detail
+
+Connect the cell’s negative terminal to **`B−` only**. Connect system ground to
+**`OUT−`**. Do **not** add an external wire directly joining `B−` to `OUT−`;
+that can bypass the protection circuit on a protected TP4056 module.
+
+The battery negative and system ground may be connected internally through the
+module’s protection circuitry. Use the module’s labeled load terminals for the
+load.
+
+---
+
+## 4. KCD11 switch operation
+
+The KCD11 is a single-pole on/off switch in the battery-to-boost path, wired
+across terminals `1` (center common) and `1b`:
+
+- **ON (closed):** connects TP4056 `OUT+` to MT3608 `IN+`.
+- **OFF (open):** disconnects the battery from the boost input.
+
+| Switch state | Contact | Result |
+|---|---|---|
+| **ON** | Closed | Battery powers the MT3608; the 5 V rail feeds the Nano and ULN2003 |
+| **OFF** | Open | Boost input is disconnected; the 5 V rail (and therefore the motor) is unpowered |
+
+The ULN2003 `VCC` is tied directly to the 5 V rail, so there is no separate
+motor cutoff. The motor is unpowered whenever the switch is off because the
+whole rail is dead. The Nano can still be powered over USB while the switch is
+off; in that case the rail—and therefore ULN2003 `VCC`—is fed from USB. See the
+debug mode in section 6.
+
+---
+
+## 5. MT3608 setup
+
+The MT3608 is adjustable; it is not a fixed 5 V supply.
+
+1. Turn the KCD11 switch **OFF**.
+2. Leave the Nano and ULN2003 disconnected.
+3. Connect the cell and measure MT3608 `OUT+` to `OUT−`.
+4. Adjust the module’s potentiometer until the output is **5.0 V**.
+5. Power-cycle and recheck the output.
+6. Connect the Nano and ULN2003 only after confirming the voltage.
+
+The module’s current capability depends on its components, input voltage, and
+cooling. The MT3608 IC’s “2 A” switch-current rating does not mean every module
+can deliver 2 A at 5 V.
+
+---
+
+## 6. Operating modes
+
+### Run from battery
+
+- KCD11: **ON**
+- Nano USB: **unplugged**
+- TP4056 charging USB: **unplugged**
+
+The Nano and motor are powered from the MT3608’s 5 V output.
+
+### Charge the battery
+
+- KCD11: **OFF**
+- TP4056 USB input: connected to a 5 V charger
+- Nano USB: **unplugged**
+
+With the switch open, the battery-powered load path is disconnected. Keep the
+Nano USB unplugged during charging as the conservative procedure.
+
+### Debug over USB serial
+
+- KCD11: **OFF**
+- TP4056 charging USB: **unplugged**
+- Nano USB: connected to the computer
+- Disconnect the MT3608 `OUT+` wire from the 5 V rail while debugging.
+
+The Nano clone has no VBUS Schottky diode. Disconnecting the boost output during
+USB debugging avoids applying USB 5 V to the MT3608 output. With the switch open
+the boost is off, but the ULN2003 `VCC` still follows the 5 V rail, which USB now
+powers through the Nano’s 5 V pin. Hold the Nano in reset (or do not run the
+sketch) so the driver does not drive the motor from USB.
+
+**Never connect Nano USB while the KCD11 is ON.** In that state, the MT3608
+supplies the Nano’s 5 V pin, which could back-feed the computer’s USB port.
+
+---
+
+## 7. First power-on checklist
+
+1. Confirm the cell goes to TP4056 `B+` and `B−`.
+2. Confirm the circuit ground goes to TP4056 `OUT−`; do not bridge `B−` to
+   `OUT−`.
+3. With the switch OFF and loads disconnected, set the MT3608 output to 5.0 V.
+4. Recheck polarity and wiring, including the KCD11 continuity check.
+5. Connect the Nano and ULN2003.
+6. Run from battery only with the switch ON and Nano USB unplugged.
+
+---
+
+## 8. Design notes
+
+- Use the Nano’s **`5V`** pin for the regulated 5 V rail. Do not use `VIN` for
+  this 5 V supply.
+- The 28BYJ-48 plugs directly into the ULN2003 board; individual coil wires
+  should not need to be jumpered.
+- Standard 28BYJ-48 ULN2003 boards do not have a current-adjustment trimmer.
+  Leave their bypass capacitors installed.
+- An optional 100–470 µF capacitor can be placed across the 5 V rail and GND
+  near the loads to help with supply dips. Observe its polarity.
+- Keep the Nano, MT3608, and ULN2003 grounds connected to the TP4056
+  `OUT−`-referenced system ground.
+- The single KCD11 pole removes the whole 5 V rail when off, so there is no
+  independent motor-supply cutoff. During USB debugging the rail and ULN2003
+  `VCC` are fed from USB, so hold the Nano in reset and disconnect the MT3608
+  `OUT+` wire.
+- Do not charge and run the load simultaneously with this simple TP4056
+  arrangement. Supporting that requires a proper power-path/load-sharing
+  design.
+
+---
+
+## 9. References
+
+These tutorials cover the stepper/driver portion of the project:
+
+- 28BYJ-48 + ULN2003 + Arduino walkthrough:  
+  https://lastminuteengineers.com/28byj48-stepper-motor-arduino-tutorial/
+- element14 stepper wiring walkthrough:  
+  https://community.element14.com/products/arduino/arduino-projects/b/blog/posts/how-to-control-28byj-48-stepper-motor-with-uln2003-driver-and-arduino
+
+TP4056 load-sharing background:
+
+- Arduino discussion of TP4056, boost converter, and Nano:  
+  https://forum.arduino.cc/t/using-li-ion-battery-with-tp4056-to-power-arduino-nano/1324112
+- TP4056 load-sharing modification discussion:  
+  https://forum.arduino.cc/t/tp4056-lithium-charger-module-modification-to-add-power-sharing/1008473

run_scan.py

@@ -40,6 +40,7 @@ TOTAL_TARGET_DEGREES = 360.0
 # Timing
 PHOTO_TO_MOVE_DELAY = 8.0
 TIMEOUT = 10.0
+MOVE_TO_PHOTO_DELAY = ROTATION_SPEED_DPS / ROTATION_STEP_SIZE + 2.0
 # ================================================
 
 
@@ -114,6 +115,20 @@ def rotate_stand(ser):
     ser.write(f"a{ROTATION_STEP_SIZE}\n".encode())
     time.sleep(0.3)
     await_completion(ser, "Waiting")
+    time.sleep(MOVE_TO_PHOTO_DELAY)  # Buffer to account for movement time
+
+
+def flush_buffer(ser):
+    """
+    Reads all currently stored bytes from the serial port until the buffer is empty.
+
+    Args:
+        ser (serial.Serial): The active serial connection to the Arduino.
+    """
+    while ser.in_waiting > 0:
+        line_bytes = ser.readline().decode("utf-8").strip()
+        line_str = line_bytes.decode("utf-8").strip()
+        print(f"[SERIAL] {line_str}")
 
 
 def await_completion(ser, s):
@@ -132,6 +147,7 @@ def await_completion(ser, s):
     while True:
         line_bytes = ser.readline()
         line_str = line_bytes.decode("utf-8").strip()
+        print(f"[SERIAL] {line_str}")
 
         if not line_str:
             raise SerialTimeoutError
@@ -141,13 +157,15 @@ def await_completion(ser, s):
 
         time.sleep(0.1)
 
+    flush_buffer(ser)
+
 
 def main():
     with serial.Serial(ARDUINO_PORT, BAUD_RATE, timeout=TIMEOUT) as ser:
         try:
             time.sleep(2.0)  # Buffer to account for Arduino startup
 
-            print("Flushing serial buffers.")
+            print("[MAIN] Flushing serial buffers.")
             ser.reset_input_buffer()
             ser.reset_output_buffer()
 
@@ -169,6 +187,8 @@ def main():
         except SerialTimeoutError:
             print("Arduino failed to respond in time.")
 
+    print("[MAIN] Done!")
+
 
 if __name__ == "__main__":
     main()