ESP32 VCR Remote

Firmware for an ESP32 DOIT DevKit v1 that emulates the infrared remote for a Panasonic PV-V4525S VCR (Omnivision 4-head Hi-Fi VHS, remote model EUR7723KA0). Commands are issued over the USB serial port.

IR codes are the IRDB Panasonic/VCR/144,0 codeset, verified against the Remote Central Pronto codes for the sibling PV-V4520. Transmission uses raw Pronto (IRsend::sendPronto) rather than encodePanasonic, because the former was empirically found to work on this specific VCR.

Hardware

• Board: ESP32 DOIT DevKit v1 (or any ESP32 — update upload_port in platformio.ini).
• IR LED driver: GPIO 4 → 2N3904 base (~470 Ω) → NPN low-side switch. LED anode to Vcc through a ~100 Ω current-limit resistor, cathode to collector, emitter to GND. Reference circuit: https://github.com/crankyoldgit/IRremoteESP8266/wiki#ir-sending
• Aim within ~6 ft of the VCR's IR window. A bare 2N3904-driven LED is weak; if a button doesn't register, move closer before suspecting the code.

Build and upload

pio run                 # compile
pio run -t upload -b <BOARD>       # compile + flash
pio device monitor  -b 115200    # open serial (115200 baud)

The upload_port and monitor_port are pinned to /dev/cu.usbserial-0001 in platformio.ini. If your board enumerates elsewhere, edit those lines or override on the command line:

pio run -t upload --upload-port /dev/cu.usbserial-XXXX
pio device monitor -p /dev/cu.usbserial-XXXX -b 115200

Sending commands via CLI

Open a serial connection at 115200 8N1, type a command, press Enter. Commands are case-insensitive.

On connect you'll see:

Panasonic PV-V4525S VCR remote. Type a command + Enter.
commands: POWER, PLAY, STOP, REW, FF, EJECT, PAUSE

Then, at the prompt (there is no prompt character — just type):

power        # toggle VCR power
play         # start playback
stop         # stop tape
rew          # rewind
ff           # fast-forward
eject        # eject tape
pause        # pause playback
?            # (or "help") reprint the command list

Each accepted command prints send <NAME> and transmits the IR frame once. Unknown input prints unknown: <input> followed by the help list.

Interactive: any of these work

The device path differs between platforms — on macOS it's /dev/cu.usbserial-0001, on Linux usually /dev/ttyUSB0. Substitute as needed.

# PlatformIO (uses upload_port from platformio.ini)
pio device monitor

# picocom — exit with Ctrl+A then Ctrl+X
picocom -b 115200 /dev/cu.usbserial-0001

# GNU screen — exit with Ctrl+A then k, then y
screen /dev/cu.usbserial-0001 115200

# minicom — exit with Ctrl+A then x
minicom -b 115200 -D /dev/cu.usbserial-0001

# cu (BSD/macOS) — exit by typing ~. on its own line
cu -l /dev/cu.usbserial-0001 -s 115200

Non-interactive: scripting one-shot commands

Configure the port once with stty, then printf to the device node. The firmware reads until \n, so newline-terminate every command.

macOS:

stty -f /dev/cu.usbserial-0001 115200 cs8 -cstopb -parenb -ixon raw
printf 'power\n' > /dev/cu.usbserial-0001
sleep 1
printf 'play\n'  > /dev/cu.usbserial-0001

Linux:

stty -F /dev/ttyUSB0 115200 cs8 -cstopb -parenb -ixon raw
printf 'power\n' > /dev/ttyUSB0

To capture the firmware's response while sending, hold the port open for reading in one shell and write from another:

# shell A: read
cat /dev/cu.usbserial-0001

# shell B: write
printf 'power\n' > /dev/cu.usbserial-0001

Note: serial ports are exclusive on macOS/Linux. Close pio device monitor, screen, picocom, etc. before scripting against the raw device node, or the writes will silently go nowhere.

Adding a new command

1. Look up the function code in the IRDB CSV: https://raw.githubusercontent.com/probonopd/irdb/master/codes/Panasonic/VCR/144,0.csv
2. Generate a Pronto frame. Given device=144, subdevice=0, and a function byte fn, the checksum is device ^ subdevice ^ fn. Each byte is transmitted LSB-first. The full frame is 48 bits wrapped in the standard Kaseikyo/Panasonic Pronto header/leader/trailer. See kIr_POWER in src/main.cpp for the layout, or copy the generator used at build time.
3. Add the new kIr_<NAME>[] array and append CMD(<NAME>) to the kCommands[] table. The dispatcher picks it up automatically.