> For the complete documentation index, see [llms.txt](https://codifi-fdm.gitbook.io/codifi-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://codifi-fdm.gitbook.io/codifi-docs/mobile-app/mapping-locations/external-gps-devices.md). # External GPS Devices Codifi works with external GPS receivers for Projects where the internal iPad GPS isn't accurate enough — typically surveying, archaeology, environmental monitoring, or any other high-precision fieldwork. This page covers pairing, switching between receivers, and troubleshooting external-GPS sessions. *** ## Supported device categories Codifi supports three categories of external GPS: | Category | What it is | Examples | | ------------------------------ | -------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------ | | **Bluetooth Low Energy (BLE)** | Standard Bluetooth-LE GPS pucks and rovers. Codifi scans for these itself. | Emlid Reach RX, RX2, RS4, RS4 Pro · EOS Arrow · FacetGNSS Rover · Garmin GLO 2 | | **MFi devices** | "Made for iPhone/iPad" certified receivers. Connect through Apple's external accessory framework rather than standard Bluetooth. | Juniper Geode, Bad Elf Mini, Trimble Catalyst | | **Trimble** | Trimble's dedicated mobility framework for higher-end Trimble receivers. | Trimble TDC600, Trimble R-series | Each category has its own pairing flow. The end result is the same: a connected receiver whose position drives the Live Data Bar and any GPS capture. When Codifi scans over BLE it filters for receivers it recognizes, either by their GPS Bluetooth service or by name. That covers **Bad Elf, Emlid, Garmin, Juniper, Leica, Topcon, Hemisphere, Septentrio, u-blox, SparkFun, Swift Navigation, NovAtel, Tersus, and Trimble**, plus model names like Reach, Arrow, Geode, Catalyst, Facet, and GLO. A receiver whose name contains GPS, GNSS, RTK, or Rover is picked up as well. {% hint style="info" %} **Emlid Reach is new in v3.3.** The Reach RX, RX2, RS4, and RS4 Pro all connect. If you have an original **Reach RX**, it needs **firmware 1.10 or newer** before Codifi can see it. Check the firmware in Emlid Flow first if the receiver never appears in the scan. {% endhint %} *** ## How to access the external-devices screen Two paths: * **Avatar menu** → **External Devices** — a top-level entry point for managing all receivers. * **Live Data Bar** → tap the **GPS source chip** (top-left of the LDB) — opens the same external-devices screen scoped to swapping the active source. Use the Avatar route when first setting things up; use the LDB chip when actively swapping between paired devices during a field day. *** ## Pairing a BLE receiver 1. Power on the receiver and confirm it's broadcasting (usually a Bluetooth status LED). 2. In Codifi, open **External Devices**. 3. Tap **+** → **BLE Device**. 4. Codifi scans for nearby BLE GPS pucks and lists what it finds. 5. Tap your receiver's name when it appears. 6. Tap **Connect**. After a successful pair, Codifi shows the receiver as the active GPS source — the Live Data Bar's GPS chip changes to the device's name, and the user position marker on the map changes color to indicate an external source. ### Saving to Favorites After pairing, **long-press** the device name in the list → **Save to Favorites**. Favorited devices auto-reconnect the next time they broadcast in range, so you don't have to repeat the pairing flow every morning. *** ## Pairing an MFi receiver MFi pairing goes through iOS's external accessory system rather than the standard Bluetooth-LE flow, so the pairing itself happens in iOS Settings rather than inside Codifi. 1. In Codifi, open **External Devices**. 2. Tap **+** → **MFi Device**. This hands you straight to **iOS Settings → Bluetooth**, because that is where an MFi receiver has to be paired. 3. Pair the receiver there, following its own instructions. Typically that means power it on, hold its pairing button, and accept on the iPad. 4. Return to Codifi. The receiver now appears in **External Devices** ready to be made the active source. MFi receivers usually offer richer NMEA streams, meaning more sentence types and a higher cadence, than BLE pucks. {% hint style="info" %} **Nothing appears after you come back?** The receiver has to finish pairing in iOS before Codifi can see it. If iOS Settings shows it as "Not Connected," tap it there to connect, then return to Codifi. {% endhint %} *** ## Pairing a Trimble receiver Trimble receivers use Trimble's own mobility framework, so the connection is managed in Trimble's app rather than in Codifi. 1. Install **Trimble Mobile Manager** and sign in to it. 2. In Codifi, open **External Devices**. 3. Tap **+** → **Trimble Device**. Codifi opens Trimble Mobile Manager and registers itself with it. 4. Connect your receiver inside Trimble Mobile Manager, then return to Codifi. The Trimble position source is now available. If Trimble Mobile Manager is not installed, nothing happens when you tap the option. Install it from the App Store first. If you're using **Trimble Catalyst**, a subscription-based MFi-style receiver, it appears in the MFi list rather than the Trimble list. *** ## What the user position marker color means The user marker on the map changes color depending on the active GPS source: | Color | Meaning | | ------------- | -------------------------------------------------------------------- | | 🔵 **Blue** | Internal iPad GPS — the default when no external receiver is paired. | | 🟠 **Orange** | An external receiver is the active source. | If you don't see the expected color, check the **GPS source chip** in the Live Data Bar — it should match the receiver you intended to use. *** ## GPS source quality indicator The GPS source chip in the LDB also carries a **color code** for signal quality: | Color | Meaning | | ------------- | --------------------------------------------------------------------------------- | | 🟢 **Green** | Fresh, stable fix. You're good. | | 🟠 **Orange** | Receiving but unstable — solar interference, partial sky view, just-acquired fix. | | 🔴 **Red** | No fix or lost signal. Wait for restoration before capturing. | For external receivers, the colors apply to that receiver's reported quality (not the iPad's internal GPS). A green internal iPad fix doesn't help if your external receiver is showing red. *** ## Swapping between paired devices mid-day Tap the **GPS source chip** in the LDB to open the external-devices screen. You'll see your paired receivers; tap one to make it active. Common reasons to swap: * **Battery management** — start with one rover, swap to a backup when the first dies. * **Different precision needs** — a high-precision Trimble for surveying, a smaller BLE puck for general work. * **Project handoffs** — one crew uses one device; another crew uses another. *** ## When the receiver goes offline mid-capture If your external receiver loses signal or dies: 1. The GPS source chip turns red. 2. Captures requiring GPS pause until the receiver recovers (or you manually fall back to internal iPad GPS). 3. The user marker stays at the last known position until a fresh fix arrives. Codifi does **not** silently fall back to internal iPad GPS — that would mix accuracies in a single dataset. You have to manually swap back to internal if you want to continue without the external receiver. To swap to internal: tap the GPS source chip → **Internal iPad GPS**. *** ## Common questions ### Do all Bluetooth GPS receivers work? Most BLE-standard ones do. If your receiver speaks standard NMEA over Bluetooth-LE, Codifi can connect. Manufacturer-locked devices that require proprietary apps may not — check with the manufacturer or the Codifi support team for confirmation. ### Why can't I find my receiver in the BLE scan? Usual causes: receiver isn't powered on, isn't in pairing mode, has been paired to another iPad and is "stuck" in that pairing, or its battery is too low to broadcast strongly. Try: power-cycle the receiver, walk closer, restart Codifi. ### My receiver is paired but Codifi says no source. Check that the receiver appears in the external-devices list AND that you've tapped it to make it active. Pairing and active-source selection are separate steps; pairing is "the device knows about you," active-source is "use this device's position right now." ### Are my receiver's NMEA logs saved anywhere? By default, no — Codifi consumes the NMEA stream for position but doesn't archive the raw sentences. Some receivers can log on-device; check your receiver's documentation. ### How precise is "high precision"? Depends entirely on the receiver. Internal iPad GPS is typically 3–10 meters in open sky. Consumer BLE pucks often deliver 1–3 meters. Survey-grade receivers (Trimble, EOS Arrow) with RTK corrections can deliver centimeter accuracy. Codifi reports whatever the receiver reports. *** ## Related * [**Live Data Bar & GPS Widgets**](/codifi-docs/mobile-app/mapping-locations/gps-and-live-data/live-data-bar-and-widgets.md) — the live readout that shows your active GPS source's data. * [**GPS Technical Reference**](/codifi-docs/mobile-app/mapping-locations/gps-and-live-data/gps-technical-reference.md) — deeper technical details on NMEA, coordinate systems, and accuracy semantics. * [**Before You Head to the Field**](/codifi-docs/mobile-app/mapping-locations/before-you-head-to-the-field.md) — pre-trip checklist that includes pairing. * [**LiveTrack & Streaming**](/codifi-docs/mobile-app/mapping-locations/livetrack-and-streaming.md) — uses your active GPS source for path capture; high-precision receivers benefit a lot here.