en_alt:receivers
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| en_alt:receivers [2026/08/11 09:36] – XIAO write-up, catalogue order, Ulm coverage entry hajo | en_alt:receivers [2026/10/12 15:04] (current) – LTE modem: name the module variant, unify the breakout name hajo | ||
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| ====== Receivers ====== | ====== Receivers ====== | ||
| - | What you need to actually hear C-ITS. There is one purpose-built receiver that most people use, and a growing number of independent projects that solve the same problem with different hardware. All of them end up in the same place: raw 802.11p frames on the [[en_alt:reporting|central MQTT broker]]. | + | What you need to actually hear C-ITS. There is one purpose-built receiver that most people use, and a growing number of independent projects that solve the same problem with different hardware. All of them end up in the same place: raw 802.11p frames on the [[en_alt:server|central MQTT broker]]. |
| Whatever you build, [[en_alt: | Whatever you build, [[en_alt: | ||
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| - [[en_alt: | - [[en_alt: | ||
| - [[en_alt: | - [[en_alt: | ||
| - | - [[en_alt:reporting|Reporting to OTM]] — how the data actually leaves the node, and how to read along | + | - [[en_alt:server|The OpenTrafficMap server]] — how the data actually leaves the node, and how to read along |
| ===== Other receiver projects ===== | ===== Other receiver projects ===== | ||
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| | [[en_alt: | | [[en_alt: | ||
| | [[en_alt: | | [[en_alt: | ||
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| Practical warning: several people have hit SPI checksum errors that turned out to be wiring problems, and some GPIOs did not work as the datasheets suggested. If the link does not come up, try different pins before you suspect the software. | Practical warning: several people have hit SPI checksum errors that turned out to be wiring problems, and some GPIOs did not work as the datasheets suggested. If the link does not come up, try different pins before you suspect the software. | ||
| - | The temporaerhaus hackerspace in Ulm documents this build end to end with two Seeed Studio XIAO boards — a **XIAO ESP32-C5** as the sniffer and a **XIAO ESP32-C3** as the Wi-Fi bridge, both stamp-sized and solderable in an evening. The page gives the exact pin mapping and links prebuilt images you can flash from the browser, so no build environment is needed. The sniffer image comes from a fork of the receiver firmware. | + | The temporaerhaus hackerspace in Ulm [[https:// |
| - | + | ||
| - | [[https:// | + | |
| **TODO:** [[https:// | **TODO:** [[https:// | ||
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| ^ Reports to OTM | yes, the same as the official board | | ^ Reports to OTM | yes, the same as the official board | | ||
| ^ Advantages | no cable to the mounting point; the '' | ^ Advantages | no cable to the mounting point; the '' | ||
| - | ^ Drawbacks | two boards and five SPI wires to get right; wiring problems are common; neither project documents a licence | + | ^ Drawbacks | two boards and five SPI wires to get right | |
| ^ Repositories | [[https:// | ^ Repositories | [[https:// | ||
| + | |||
| + | ==== 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**, | ||
| + | |||
| + | Wiring is three jumper wires and no soldering if the breakout' | ||
| + | |||
| + | | '' | ||
| + | | '' | ||
| + | | '' | ||
| + | |||
| + | {{: | ||
| + | //Three jumper wires link the modem breakout to the ESP32-C5; the orange cable is the modem' | ||
| + | |||
| + | **Power the modem separately.** This is the one thing that will bite you. Leave the breakout' | ||
| + | |||
| + | 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/ | ||
| + | |||
| + | The modem also has **GNSS**, switched off by default because the antenna is optional. Enabled through '' | ||
| + | |||
| + | **Keep the LTE and GNSS antennas well away from the ESP32' | ||
| + | |||
| + | //Not in a release yet: this is [[https:// | ||
| + | |||
| + | ^ 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 '' | ||
| + | ^ 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:// | ||
| ==== Mobile 5G setup ==== | ==== Mobile 5G setup ==== | ||
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| ^ Reports to OTM | yes, with the supplied example configuration | | ^ Reports to OTM | yes, with the supplied example configuration | | ||
| ^ Advantages | frames become Home Assistant data; free choice of uplink and destination; | ^ Advantages | frames become Home Assistant data; free choice of uplink and destination; | ||
| - | ^ Drawbacks | no Wi-Fi; the KSZ8851SNL path is experimental; no licence stated in the repository | + | ^ Drawbacks | no Wi-Fi; the KSZ8851SNL path is experimental | |
| ^ Repository | [[https:// | ^ Repository | [[https:// | ||
| - | Note that this is a different thing from **monitoring** a node in Home Assistant, where the node runs on its own and Home Assistant simply reads its telemetry. That is described under [[en_alt:reporting# | + | Note that this is a different thing from **monitoring** a node in Home Assistant, where the node runs on its own and Home Assistant simply reads its telemetry. That is described under [[en_alt:server# |
| ==== USB to an Android phone ==== | ==== USB to an Android phone ==== | ||
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| ^ Reports to OTM | **no** | | ^ Reports to OTM | **no** | | ||
| ^ Advantages | small, single-file code base; straight to PCAP and Wireshark; no ESP-IDF toolchain needed | | ^ Advantages | small, single-file code base; straight to PCAP and Wireshark; no ESP-IDF toolchain needed | | ||
| - | ^ Drawbacks | no OTM upload, no Ethernet, no runtime configuration; | + | ^ Drawbacks | no OTM upload, no Ethernet, no runtime configuration; |
| ^ Repository | [[https:// | ^ Repository | [[https:// | ||
en_alt/receivers.1786433795.txt.gz · Last modified: by hajo