Differences

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--- en_alt:receivers [2026/08/15 00:06] – Renamed to The OpenTrafficMap server; Berlin coverage; imprint moved hajo
+++ en_alt:receivers [2026/10/12 15:04] (current) – LTE modem: name the module variant, unify the breakout name hajo
@@ Line 178: / Line 178: @@
 | [[en_alt:receivers#diy_ethernet|DIY Ethernet]] | any ESP32-C5 + W5500 or ENC28J60 | Ethernet | yes |
 | [[en_alt:receivers#wi-fi_via_spi-eppp|Wi-Fi via SPI-EPPP]] | ESP32-C5 + a second ESP32 | Wi-Fi via the second chip | yes |
+| [[en_alt:receivers#lte_modem|LTE modem]] | ESP32-C5 + SIMCom A7670E modem | LTE, PPP over UART | yes |
 | [[en_alt:receivers#mobile_5g_setup|Mobile 5G setup]] | FireBeetle 2 ESP32-C5 + W5500 | 5G router with an Ethernet port | yes |
 | [[en_alt:receivers#esphome_firmware|ESPHome firmware]] | official board or any ESP32-C5 | your choice | with the supplied example config |
@@ Line 232: / Line 233: @@
 ^ Drawbacks | two boards and five SPI wires to get right |
 ^ Repositories | [[https://github.com/hn/esp32-spi-eppp-server|hn]] · [[https://github.com/robbi5/esp32-spi-eppp-server|robbi5]] |
+==== LTE modem ====
+For a spot with no Ethernet and no Wi-Fi at all: a mast in a field, a rooftop without a cable run, a vehicle. Instead of bridging to somebody else's network, the receiver brings its own — a **SIMCom A7670E** cellular modem on the AND BKP-A7670E breakout, connected over UART and speaking PPP.
+**Watch out when buying:** it comes in regional and feature variants that differ in the LTE bands and in whether GNSS is fitted — this one is an **A7670E-MASA**, European bands with GNSS.
+Wiring is three jumper wires and no soldering if the breakout's header is populated; the board's TXD and RXD are 3.3 V TTL, so no level shifter is needed either:
+| ''GPIO8'' (UART1 TX) | → | ''R'' (modem RXD) |
+| ''GPIO9'' (UART1 RX) | → | ''T'' (modem TXD) |
+| ''GND'' | → | ''G'' |
+{{:esp32-c5-a7670e-lte.jpg?0x420|A SIMCom A7670E on the AND BKP-A7670E breakout, wired to an ESP32-C5 board with three jumper wires}} \\
+//Three jumper wires link the modem breakout to the ESP32-C5; the orange cable is the modem's own USB power supply. Note the three antennas that have to share the space: LTE (flat patch, left), GNSS (square ceramic, top right) and the receiver's own 5.9 GHz antenna (white, right).//
+**Power the modem separately.** This is the one thing that will bite you. Leave the breakout's ''V'' pin unconnected and feed the modem from its own micro-USB jack with **5 V and at least 2 A** — transmit bursts draw up to about 2 A, and running it off the MCU board drops the rail into the brownout detector. A supply that is merely weak does not produce an error message: the modem simply reboots under load and the link keeps dropping. The regulator on the breakout is linear, so do not feed it 9 or 12 V; the difference just becomes heat.
+Configuration is two console commands, and both take effect on the next boot:
+  config set lteapn internet
+  config set ltesimpin 1234
+The APN can often be left alone — where the operator supplies one, the modem picks it up by itself. The SIM PIN is only needed if the card has one. Note that in this variant the console is on **USB-Serial/JTAG**, not on UART0 as in the Ethernet builds, because the ESP32-C5 Mini has no second port and the prompt has to stay reachable to set the APN at all.
+The modem also has **GNSS**, switched off by default because the antenna is optional. Enabled through ''LTE_SIMCOM_GNSS'' in ''menuconfig'', it multiplexes the single UART so the position can be read while PPP is up, at the cost of a slightly less reliable link bring-up. The ''lte'' console command then shows the link state and the last fix. The position is **not** sent to OpenTrafficMap — the code exists but is disabled, because there is no endpoint for it yet.
+**Keep the LTE and GNSS antennas well away from the ESP32's antenna.** The modem transmits at +23 dBm, and on LTE band 3 its third harmonic falls into the lower 5 GHz channels — so a badly placed modem antenna will quietly cost you C-ITS reception. See [[en_alt:placement#interference|Interference]] for the same problem with Wi-Fi access points.
+//Not in a release yet: this is [[https://codeberg.org/opentrafficmap/its-g5-receiver-firmware/pulls/30|pull request #30]], which builds on [[https://codeberg.org/opentrafficmap/its-g5-receiver-firmware/pulls/29|#29]]. For now you build it from the branch.//
+^ Hardware | an ESP32-C5 board, a SIMCom A7670E-MASA on the AND BKP-A7670E breakout, a SIM card, and a separate 5 V / 2 A supply for the modem |
+^ Firmware | official firmware with ''sdkconfig.proto-lte-a7670'' — currently only in pull request #30 |
+^ Uplink | LTE, PPP over UART |
+^ Reports to OTM | yes, the same as the official board |
+^ Advantages | completely independent of local infrastructure — power and a SIM are enough; no second chip and no router; optional GNSS gives the node its own position |
+^ Drawbacks | needs a SIM and a data plan; the second power supply is mandatory, not optional; the modem can desensitise the C-ITS receiver if the antennas sit close together; not merged, so you build it yourself |
+^ Repository | [[https://codeberg.org/opentrafficmap/its-g5-receiver-firmware/pulls/30|its-g5-receiver-firmware PR #30]] |
 ==== Mobile 5G setup ====