AnyScan209 Live Scan – Bluetooth Protocol for External Scanners (ANY_SCAN_MS209)

1. What Live Scan Mode Does

In Live Scan mode a microcontroller with a Bluetooth serial module (HC-05, HC-06 or any SPP device) streams sensor readings to AnyScan209. The app can receive one sensor or four sensors at the same time, so a four-sensor scanner fills four rows at once and scans four times faster. The scanner also reports its battery level, which the app shows as a progress bar with a low-battery alarm.

Without the special name described below, the app stays in simple external mode: every incoming input moves the scan forward by one step. Both modes work, so scanners you already built keep working.

2. Enable Live Scan: Set the Bluetooth Name

Rename your Bluetooth module to exactly:

Copy the name exactly, including the underscores and digits. Most modules are renamed with an AT command, for example AT+NAME=ANY_SCAN_MS209 on an HC-05 (the command differs between modules, so check your module's datasheet). After renaming, pair the phone with the module again so the new name appears.

3. Single Scan or Four-Sensor Scan

After the name is set, choose the scan type in the app options to match your hardware:

• Single scan: one sensor, such as one magnetometer or one metal detector. The scan moves forward one row at a time.
• Four-sensor scan: four sensors send their values at the same moment and four rows are filled at once.

The option in the app must match what the scanner sends (see the next section). Scanning starts from the scan button in the app, or when the scanner sends the word Next.

4. Data Packet Format

Every scan packet is a numeric string of exactly 20 characters: five fields of four digits, each from 0000 to 1024 and always padded with leading zeros. Each packet ends with a normal line break (CR+LF), which Print in BASCOM and println in Arduino add automatically.

Single-scan packet

Field 1 holds the real value, fields 2–4 are sent as 0000, field 5 is the battery.

0512 0000 0000 0000 0980   →   send as   05120000000000000980

Four-sensor packet

All four sensor fields hold real values.

0512 0300 0700 0090 0980   →   send as   05120300070000900980

Keep every value between 0 and 1024 (a 10-bit ADC range). The app clamps sensor values to a small safety margin beyond that range, but a well-behaved sender stays inside 0–1024.

5. Command Words: Next and Bal

Two optional words let the user control the app from the scanner. Send the word alone on its own line.

Both words are optional. They are meant for two hardware buttons on the scanner, so the user does not have to touch the phone each time. If you skip the buttons nothing breaks: the app already has an on-screen scan button and a balance button. Adding the two hardware buttons is recommended for comfort.

6. Battery Display and Alarm

The app knows nothing about voltages. Field 5 is just a number, and your scanner is responsible for mapping its real battery voltage to that number. The app turns the number into a percentage with a linear formula, averages 50 packets before updating the bar (so the icon does not flicker), and colors the bar from dark red (low) to yellow-green (full).

Percentage formulas used by the app: magnetometer (value − 600) / 2.6, metal detector (value − 820) / 2.04; at or below the empty point the bar shows 3%.

Mapping your battery to the number

Choose the empty and full voltages of your battery, then map linearly:

number = emptyNumber + (voltage − emptyVoltage) × (fullNumber − emptyNumber) / (fullVoltage − emptyVoltage)

Example, single lithium cell (3.3 V empty, 4.2 V full) on a magnetometer: number = 600 + (voltage − 3.3) × 260 / 0.9. The same formula works for any battery: 3.3–4.2 V, 9.6–12.4 V, 14–18 V and so on. Only the empty and full voltages change.

7. Voltage Divider

A microcontroller ADC can only read voltages up to its reference voltage, so a higher battery voltage must be reduced by a resistor voltage divider before it reaches the ADC pin. Designing the divider (resistor values, accuracy, protecting the ADC pin) is entirely the builder's responsibility.

The relationship between divided voltage and ADC value is nearly linear. If your divider cannot hit the ranges above exactly, correct the value in your microcontroller code with the mapping formula. Any AI assistant can calculate the resistors and the code for you (see section 9).

8. Sender Code: BASCOM, Arduino, Python

BASCOM (AVR)

This follows the reference scanner: one sensor on ADC0, battery on ADC1 with a fixed offset of 305 so the number lands in the range the app expects. Calibrate the offset for your own hardware.

Dim Volt1 As Word
Dim Sampl1 As Word
Dim Magno11 As String * 4
Dim Volt11 As String * 4
Dim Volt12 As String * 4

Sampl1 = Getadc(0)
Volt1 = Getadc(1) + 305            ' calibrate: empty battery = 600, full = 860

Magno11 = Str(sampl1) : Magno11 = Format(magno11 , "0000")
Volt11 = Str(volt1)   : Volt12 = Format(volt11 , "0000")

' Single scan: the three unused fields are mandatory
Print #1 , Magno11 ; "0000" ; "0000" ; "0000" ; Volt12

' Balance button
Print #1 , "Bal"

Arduino (four-sensor example)

const float V_EMPTY = 3.3, V_FULL = 4.2;   // your battery
const int   N_EMPTY = 600, N_FULL = 860;   // magnetometer (metal detector: 820 to 1024)
const float ADC_REF = 5.0;                 // ADC reference voltage
const float DIVIDER = 1.0;                 // (R1+R2)/R2 of your voltage divider

int batteryNumber() {
  float v = analogRead(A4) * ADC_REF / 1023.0 * DIVIDER;
  float n = N_EMPTY + (v - V_EMPTY) * (N_FULL - N_EMPTY) / (V_FULL - V_EMPTY);
  return constrain((int)n, 0, 1024);
}

void sendScan(int s1, int s2, int s3, int s4) {
  char buf[21];
  snprintf(buf, sizeof(buf), "%04d%04d%04d%04d%04d",
           constrain(s1, 0, 1024), constrain(s2, 0, 1024),
           constrain(s3, 0, 1024), constrain(s4, 0, 1024),
           batteryNumber());
  Serial.println(buf);          // or bluetooth.println(buf)
}

void loop() {
  // Four-sensor mode
  sendScan(analogRead(A0), analogRead(A1), analogRead(A2), analogRead(A3));
  // Single-scan mode: sendScan(analogRead(A0), 0, 0, 0);

  // Optional buttons
  // if (digitalRead(NEXT_PIN) == LOW) Serial.println("Next");
  // if (digitalRead(BAL_PIN)  == LOW) Serial.println("Bal");
}

Python (MicroPython or desktop test)

def make_packet(s1, s2=0, s3=0, s4=0, batt=0):
    vals = [max(0, min(1024, v)) for v in (s1, s2, s3, s4, batt)]
    return "".join(f"{v:04d}" for v in vals)

print(make_packet(512, 300, 700, 90, 980))  # 05120300070000900980
print(make_packet(512, batt=980))           # 05120000000000000980

Test with a serial terminal first: every line must be exactly 20 digits.

9. Let an AI Write Your Sender Code

You do not need to be an embedded expert. Copy this page into an AI assistant and ask for the code for your board. A good request looks like this:

The assistant should ask for your microcontroller, language, Bluetooth baud rate, scan type (single or four), device type (magnetometer or metal detector), battery empty and full voltages, and the ADC reference voltage. Then it designs the divider, writes the battery mapping, builds the 20-character packet and reminds you to rename the Bluetooth module to ANY_SCAN_MS209.

10. FAQ

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