title: "Remote control fireplace"

---
title: "Remote control fireplace"
date: 2020-11-25
---

Last year Sarah and I bought a *Regal Flame Spectrum Modern Linear Electric 3
Sided Wall Mounted Built-in Recessed Fireplace (50")* and installed it under
our TV. One problem is that it comes with an annoying little remote that we
keep losing track of, so I decided to hook up a Raspberry Pi to allow us to
control it with our phones.

image:product.jpg[Product photo from online]
image:installed.jpg[Installed under TV]

First I set up a Raspberry Pi Zero W with Void Linux, and
connected a 38kHz Vishay TSOP38238 receiver to one of its GPIO
pins. These IR receivers are well supported on Raspberry Pi,
and all I needed to do was add these line to /boot/config.txt:

```
dtoverlay=gpio-ir,gpio_pin=17
dtoverlay=gpio-ir-tx,gpio_pin=4
```

## Hardware

I needed to know what type of codes were being sent by the remote (Sony,
Philips, NEC). I looked at the waveform with an oscilloscope and figured out
that it was sending NEC codes. Then I used the program **ir-ctl** from
**v4l-utils** to figure out which codes were sent for which buttons.

Then I breadboarded a small circuit to drive an LED with a transistor, and I
went to my parts bin and found a bunch of IR LEDs tried each of them until I
found an LED that transmitted at the correct IR wavelength to be picked up by
the fireplace. I soldered the LED and the transistor to a piece of protoboard
and mounted it tucked under the mantel aiming at the IR receiver.

## Software

The heater temperature needs to be set every time the unit is turned on. I
wrote a shell script that simulates the sequence of button presses that turns
on the heater to full strength and sets the temperature cutoff to 82°F.

```sh
#!/bin/sh

TIMER=0x8006
BG_BRIGHTNESS=0x800a
ON=0x8012
LOG_BRIGHTNESS=0x8019
STRENGTH=0x801e
TEMP=0x801f

press () {
ir-ctl -S nec:$1
}

press $ON

press $STRENGTH
press $STRENGTH
press $STRENGTH

press $TEMP
press $TEMP
press $TEMP
press $TEMP
press $TEMP
press $TEMP
press $TEMP
```

## Idempotent power control

I would prefer to have some way of explicitly turning the fireplace on or off, rather than just toggling the power state. I found that if I quickly send a sequence like TEMP-POWER, the fireplace will skip processing the POWER keypress if it's already on, which can be used as a "turn the fireplace on, or leave the fireplace on" primitive. However it's not very reliable and I haven't found a more reliable method yet, so for now I just have a single "toggle" control that switches it from off->on or vice versa. The fireplace beeps after every button press so we can hear when it's toggled on because it beeps a bunch of times, whereas when it's toggled off it only beeps once for the initial POWER button press.

## Homeassistant

I use Homeassistant to control some things in my house, so I added these lines to configuration.yaml to allow us to toggle the fireplace from our phones:

_configuration.yaml_:
```yaml
shell_command:
fireplace_toggle: ssh -i /config/fireplace_ssh -o UserKnownHostsFile=/config/ssh_known_hosts root@fireplace toggle

light:
- platform: template
lights:
fireplace:
turn_on:
service: shell_command.fireplace_toggle
turn_off:
service: shell_command.fireplace_toggle
```

And then I'm using [`ssh_command` as described in another post](http://blog.qartis.com/lazy_hardened_void_linux_raspberry_pi/#optional-allow-some-unprivileged-ssh-commands) to only allow the fireplace_ssh key to run the `toggle` command.