ATU-1000 ESP32-S3 Controller

ESP32-S3 replacement controller firmware for the ATU-1000 (and variants) automatic antenna tuner, replacing the original PIC16F1938 microcontroller.

Features

7x7 L-network tuner control (7 inductors, 7 capacitors, 1 topology relay)
SWR and power measurement with calibration
20x4 I2C LCD display with power bargraph
Frequency memory - stores tuning settings per frequency
Multi-protocol CAT support (Kenwood, Icom, Yaesu)
Auto-tune on SWR threshold
Power protection (configurable limit, default 1000W)
Serial command interface for control and diagnostics

Building

Prerequisites

PlatformIO (CLI or IDE)
ESP32-S3 development board

Build Commands

# Build
pio run

# Build and upload
pio run -t upload

# Monitor serial output
pio device monitor -b 115200

Flashing

Connect ESP32-S3 via USB
Run pio run -t upload
Open serial monitor at 115200 baud

First boot will show NVS "NOT_FOUND" errors - this is normal (no saved settings yet).

Serial Commands

General

Command	Description
`help`	Show all commands
`status`	Show current state (SWR, power, frequency, relay masks)

Tuning

Command	Description
`tune`	Start tuning (requires RF power)
`tune force`	Force tune without RF power check
`bypass on/off`	Enable/disable bypass mode
`auto on/off`	Enable/disable auto-tune
`freq <hz>`	Set frequency manually (e.g., `freq 14200000`)

Relay Control

Command	Description
`l <hex>`	Set L relay mask (e.g., `l 01` for first inductor only)
`c <hex>`	Set C relay mask (e.g., `c 7f` for all capacitors)
`topo hi/lo`	Set topology relay (Hi-Z or Lo-Z)

Individual Relay Commands

L Relays (Inductors):

l 01    # K1 ON  (0.05uH)
l 02    # K4 ON  (0.1uH)
l 04    # K6 ON  (0.22uH)
l 08    # K8 ON  (0.45uH)
l 10    # K10 ON (1.0uH)
l 20    # K12 ON (2.2uH)
l 40    # K14 ON (4.7uH)
l 00    # All OFF

C Relays (Capacitors):

c 01    # K3 ON  (10pF)
c 02    # K5 ON  (22pF)
c 04    # K7 ON  (47pF)
c 08    # K9 ON  (100pF)
c 10    # K11 ON (220pF)
c 20    # K13 ON (470pF)
c 40    # K15 ON (1nF)
c 00    # All OFF

Diagnostics

Command	Description
`raw`	Show raw ADC values and calculated SWR/power
`cal`	Show calibration constants
`i2cscan`	Scan I2C bus for devices

Memory

Command	Description
`mem size`	Show number of stored frequency/settings pairs
`mem clear`	Clear all stored tuning memory

Power Protection

Command	Description
`power reset`	Reset overload protection and clear bypass
`power off`	Disable power protection (for testing)
`power on`	Enable power protection

CAT Control

Command	Description
`cat kenwood`	Set CAT protocol to Kenwood/Elecraft
`cat icom`	Set CAT protocol to Icom CI-V
`cat yaesu`	Set CAT protocol to Yaesu
`cat auto`	Auto-detect CAT protocol

SWR Sweep

Command	Description
`sweep <startMHz> <endMHz> [stepkHz] [dwellMs]`	Run SWR sweep (requires CAT TX control)

SWR Bridge Calibration

Initial Setup

Disable power protection during calibration: power off
Connect a 50-ohm dummy load
Transmit at a known power level (e.g., 25W)
Run raw to see ADC readings

Calibration Values

Edit include/Config.h to adjust these values:

.fwdOffsetMv = 15.0f,       // Diode forward voltage drop (mV)
.revOffsetMv = 15.0f,
.fwdScale = 1.0f,           // Voltage scaling factor
.revScale = 1.0f,
.powerScale = 0.03f,        // V^2 to Watts conversion
.swrMinForward = 30.0f,     // Minimum mV for valid SWR reading

Power Scale Calculation

The power formula is: Power = (Vfwd - offset)^2 / powerScale

To calculate powerScale:

Transmit known power (e.g., 25W) into dummy load
Run raw to get FWD mV reading
Calculate: powerScale = (Vfwd_mV/1000 - offset/1000)^2 / actual_power

Example:

Transmitting 25W
FWD reads 873mV, offset is 15mV
powerScale = (0.873 - 0.015)^2 / 25 = 0.736 / 25 = 0.0294

Verifying Calibration

Transmit into dummy load at various power levels
Run raw and verify power reading matches actual power
SWR should read ~1.0 into 50-ohm load

Note: Diode detectors have some non-linearity. Calibrate at your typical operating power for best accuracy.

Display Layout

20x4 LCD display showing:

Line 0: [CAT] [FREQ  ] [M]
Line 1: [SWR] [BARGRAPH] [PWR]
Line 2: [L value] [C value] [T][B]
Line 3: [STATUS MESSAGE     ]

Line 0 - CAT/Frequency

CAT or --- - CAT connection status
14.200 or --.--- - Current frequency in MHz
A or M - Auto-tune or Manual mode

Line 1 - SWR/Power

S1.5 - SWR value (or S>10 if very high)
Bargraph - Visual power indicator (6 characters)
25W - Power in watts (or !OVL! / WARN)

Line 2 - Tuner State

2.20uH - Total inductance switched in
470pF - Total capacitance switched in
H or L - Hi-Z or Lo-Z topology
B or space - Bypass mode indicator

Line 3 - Status

Shows current status messages:

READY - Idle, ready to tune
TUNING - Tune in progress
TUNE OK - Successful tune
TUNE FAIL - Could not achieve target SWR
NO RF - Insufficient power to tune
PWR HIGH - Power too high for tuning
MEM HIT - Loaded settings from memory
MEM MISS - No stored settings for frequency
BYPASS - Bypass mode active
!OVERLOAD! - Power protection triggered

Configuration

Key settings in include/Config.h:

Power Thresholds

.minTunePowerW = 1.0f,      // Minimum power to tune
.maxTunePowerW = 50.0f,     // Maximum power for tuning
.minAutoRetunePowerW = 3.0f, // Minimum for auto-retune

SWR Thresholds

.targetSWR = 1.2f,          // Target SWR for "success"
.goodSWR = 1.5f,            // Acceptable SWR for "good enough"
.autoRetuneSWR = 2.5f,      // SWR threshold for auto-retune

LCD Settings

.lcdAddress = 0x27,         // I2C address (try 0x3F if not found)
.lcdCols = 20,
.lcdRows = 4,

Button Functions

Button	Short Press	Long Press
Tune (GPIO 0)	Normal tune (requires RF)	Force tune
Bypass (GPIO 3)	Toggle bypass mode	-
Auto (GPIO 4)	Toggle auto-tune	-

Troubleshooting

Display Not Working

Run i2cscan to verify I2C device detected
Check I2C address (0x27 or 0x3F common)
Verify SDA/SCL wiring and pull-up resistors

False Power Overload

ADC pins reading noise when SWR bridge not connected
Use power off during testing without bridge
Use power reset to clear overload state

SWR/Power Readings Wrong

Check FWD/REV are not swapped
Verify with raw command and compare to DVM measurements
Adjust calibration values in Config.h

Relays Not Switching

Test individual relays with l XX and c XX commands
Verify 3.3V logic is sufficient for MJD122 transistor drive
Check wiring from ESP32 GPIO to PIC socket pins

Files

ATU-1000/
├── platformio.ini          # PlatformIO project config
├── README.md               # This file
├── hardware.md             # Hardware pin mapping details
├── license.md              # License information
├── include/
│   └── Config.h            # Pin mappings, tuning constants, calibration
├── src/
│   └── main.cpp            # Complete firmware implementation
└── Archive/
    ├── schematic/          # Schematic images and PIC disassembly
    └── Firmware/           # Original PIC hex files

Name		Name	Last commit message	Last commit date
ATU-1000 - OLED		ATU-1000 - OLED
ATU-1000 LCD		ATU-1000 LCD
README.md		README.md

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