MULTILARM // FIELD NOTES
Worship · Worked Example

The $45 Virtual Muezzin

Running daily Adhan on a Raspberry Pi · 6 min read

Illustrative worked example — a representative scenario showing how Multilarm is configured, not an account of a specific customer.

There are plenty of commercial Adhan clocks. Most are locked-down appliances with a handful of built-in recitations, an LCD panel that fades after five years, and firmware that will never be updated. You can replace one of them with a $35 Raspberry Pi, a $10 amplified speaker, and a single XML file.

The setup

Picture a small prayer room that wants its own adhan without touching the main mosque’s PA feed. The hardware is deliberately boring:

That’s the whole bill of materials. There is no database, no cloud account to register, no firmware to update from a vendor portal. The Pi is on the local Wi-Fi, and that is it.

The schedule

Prayer times are built out once for the whole year and pasted into DateAndTimeData. Each row is one calendar date carrying the five daily prayer times; Multilarm picks the row matching today’s date and fires each slot at its configured time. A pared-down extract from Multilarm.config.xml looks like this:

<MAConfig><DateIdentifier>*</DateIdentifier></MAConfig>
<MAConfig><DateDelimiter>-</DateDelimiter></MAConfig>
<MAConfig><TimeDelimiter>|</TimeDelimiter></MAConfig>
<MAConfig><MonthFirst>False</MonthFirst></MAConfig>
<MAConfig><UKDaylightSavings>True</UKDaylightSavings></MAConfig>
<MAConfig><AlarmPath>{app}/Adhan/Fajr|{app}/Adhan/Standard</AlarmPath></MAConfig>
<MAConfig><AlarmIndexData>1|2|2|2|2</AlarmIndexData></MAConfig>
<MAConfig><AlarmFileFormat>mp3</AlarmFileFormat></MAConfig>
<MAConfig><DateAndTimeData>*1-1|6:27|12:07|14:13|16:01|17:47*2-1|6:27|12:08|14:14|16:02|17:48</DateAndTimeData></MAConfig>

The leading * is the DateIdentifier marking each date row; dates use the D-M form because MonthFirst is false. AlarmIndexData routes slot 1 (Fajr) to folder index 1 (Adhan/Fajr — recordings with as-salatu khayrun minan-nawm) and slots 2–5 to index 2 (Adhan/Standard). Each folder holds several recitations. Multilarm picks one at random for each fire. The congregation hears a different Qari most days without anyone touching the Pi. When the imam publishes the next month’s timings, only the matching rows are rewritten and Multilarm hot-reloads the file automatically.

Time-based volume control

Volume needs vary by time of day — an indoor prayer room may want a measured level overnight and full presence by mid-morning. Multilarm’s Volume Profile Rules set the cap for any hours you choose, applied automatically without editing the schedule. One setting, one line:

<MAConfig><VolumeProfileRules>22:00-06:00,volume=0.55</VolumeProfileRules></MAConfig>

The rule format is time-range,volume=0.0-1.0; additional rules are semicolon-separated. The status dashboard reflects the active window in its own field (volumeProfile in the JSON, Volume Profile in the UI), so you can see at a glance which cap is currently clipping the schedule.

Skipping a prayer without touching the Pi

Here is the scenario that sells the Web Remote: travel day. The imam is out, the congregation is praying at a different time, and the mu’adhin has five minutes before the fixed Adhan fires from the timer. In the old appliance era, somebody would have physically unplugged the thing.

In Multilarm, it’s one tap on any phone on the local Wi-Fi:

Open http://multilarm-pi.local/ → log in → tap Skip Next Alarm.

Under the hood that is a single POST to /api/skip against the built-in HTTP listener. The next fire is acknowledged as “skipped”, written to the playlist log with a reason, and the schedule continues untouched thereafter.

Why this matters: the alternative is editing a config file at 04:30 with shaky hands, or ripping the power out and forgetting to plug it back in for Maghrib. The Web Remote turns a governance problem into a one-button action.

Voice Broadcast for janazah and announcements

Not every message is scheduled. Janazah prayer times are short-notice. The Voice Broadcast card in the Web Remote lets any authorised phone on the network record a short announcement, preview it locally on the Pi, and then transmit it out of the speaker — no uploads, no editing, no audio software.

The flow is exactly three buttons:

  1. Record — the Pi starts capturing from the configured recording device (setting #25).
  2. Preview — plays it back once through the speaker so you know it came out right.
  3. Transmit — a confirmation dialog pops up, then the recording goes out over the regular alarm output at the configured broadcast volume.

If anything sounds off, Discard throws the recording away and you start over. For mosques with a different workflow (recording on a phone first, uploading afterwards), the Upload button accepts mp3, ogg, wav or aiff files up to 16 MB.

What it replaced, practically

The previous appliance in this prayer room was a £180 device that did one thing: play one of five built-in Adhans at times you entered with a rubbery keypad. When its LCD started ghosting, replacement was the only option — the vendor didn’t ship parts.

The Pi costs about £40, and a powered speaker is often already on hand. Multilarm ships with free-licensed sample recitations (public-domain and Creative Commons works from Wikimedia Commons) to get going, and a site can drop in its own licensed recordings in their place. Multilarm itself is free. And when the Pi eventually dies, you plug the SD card into a new Pi and the exact same schedule boots up unchanged.

Takeaways

Grab the binary and the sample config on the downloads page. There is no licence key, no activation server, and no expiry — though commercial deployments (mosques, schools, businesses) need a commercial licence; the software itself stays unlocked.