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243 lines
14 KiB
243 lines
14 KiB
ESP-LINK
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========
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This firmware connects an attached micro-controller to the internet using a ESP8266 Wifi module.
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It implements a number of features:
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- transparent bridge between Wifi and serial, useful for debugging or inputting into a uC
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- flash-programming attached Arduino/AVR microcontrollers as well as LPC800-series and other
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ARM microcontrollers via Wifi
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- outbound TCP (and thus HTTP) connections from the attached micro-controller to the internet
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- outbound REST HTTP requests from the attached micro-controller to the internet, protocol
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based on espduino and compatible with [tuanpmt/espduino](https://github.com/tuanpmt/espduino)
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The firmware includes a tiny HTTP server based on
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[esphttpd](http://www.esp8266.com/viewforum.php?f=34)
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with a simple web interface, many thanks to Jeroen Domburg for making it available!
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Many thanks to https://github.com/brunnels for contributions around the espduino functionality.
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###[Releases](https://github.com/jeelabs/esp-link/releases)
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- [V2.0.beta2](https://github.com/jeelabs/esp-link/releases/tag/v2.0.beta2) has REST support but
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requires a 1MByte or 4MByte ESP8266 flash, e.g. esp-12 or wroom-02
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- [V1.0.1](https://github.com/jeelabs/esp-link/releases/tag/v1.0.1) is _stable_
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and has the web server, transparent bridge, flash-programming support, but lacks
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the REST and upcoming MQTT support. V1 works with 512KB flash, e.g. esp-1, esp-3, ...
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For quick support and questions:
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[](https://gitter.im/jeelabs/esp-link?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
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Eye Candy
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---------
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These screen shots show the Home page, the Wifi configuration page, the console for the
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attached microcontroller, and the pin assignments card:
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<img width="45%" src="https://cloud.githubusercontent.com/assets/39480/8261425/6ca395a6-167f-11e5-8e92-77150371135a.png">
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<img width="45%" src="https://cloud.githubusercontent.com/assets/39480/8261427/6caf7326-167f-11e5-8085-bc8b20159b2b.png">
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<img width="45%" src="https://cloud.githubusercontent.com/assets/39480/8261426/6ca7f75e-167f-11e5-827d-9a1c582ad05d.png">
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<img width="30%" src="https://cloud.githubusercontent.com/assets/39480/8261658/11e6c64a-1681-11e5-82d0-ea5ec90a6ddb.png">
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Hardware info
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-------------
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This firmware is designed for esp8266 modules which have most ESP I/O pins available and
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at least 1MB flash. (The V1 firmware supports modules with 512KB flash).
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The default connections are:
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- URXD: connect to TX of microcontroller
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- UTXD: connect to RX of microcontroller
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- GPIO12: connect to RESET of microcontroller
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- GPIO13: connect to ISP of LPC/ARM microcontroller (not used with Arduino/AVR)
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- GPIO0: optionally connect green "conn" LED to 3.3V (indicates wifi status)
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- GPIO2: optionally connect yellow "ser" LED to 3.3V (indicates serial activity)
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If you are using an FTDI connector, GPIO12 goes to DTR and GPIO13 goes to CTS.
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If you are using an esp-12 module, you can avoid the initial boot message from the esp8266
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bootloader by using the swap-pins option. This swaps the esp8266 TX/RX to gpio15/gpio13 respectively.
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The GPIO pin assignments can be changed dynamically in the web UI and are saved in flash.
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Initial flashing
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----------------
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(This is not necessary if you receive one of the jn-esp or esp-bridge modules from the author!)
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If you want to simply flash the provided firmware binary, you can download the latest
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[release](https://github.com/jeelabs/esp-link/releases) and use your favorite
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ESP8266 flashing tool to flash the bootloader, the firmware, and blank settings.
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Detailed instructions are provided in the release notes.
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Note that the firmware assumes a 512KB flash chip, which most of the esp-01 thru esp-11
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modules appear to have. A larger flash chip should work but has not been tested.
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Wifi configuration overview
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------------------
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For proper operation the end state the esp-link needs to arrive at is to have it
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join your pre-existing wifi network as a pure station.
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However, in order to get there the esp-link will start out as an access point and you'll have
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to join its network to configure it. The short version is:
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1. the esp-link creates a wifi access point with an SSID of the form `ESP_012ABC`
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2. you join your laptop or phone to the esp-link's network as a station and you configure
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the esp-link wifi with your network info by pointing your browser at http://192.168.4.1/
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3. the esp-link starts to connect to your network while continuing to also be an access point
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("AP+STA"), the esp-link may show up with a `esp-link.local` hostname
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(depends on your DHCP/DNS config)
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4. the esp-link succeeds in connecting and shuts down its own access point after 15 seconds,
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you reconnect your laptop/phone to your normal network and access esp-link via its hostname
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or IP address
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LED indicators
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--------------
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Assuming appropriate hardware attached to GPIO pins, the green "conn" LED will show the wifi
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status as follows:
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- Very short flash once a second: not connected to a network and running as AP+STA, i.e.
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trying to connect to the configured network
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- Very short flash once every two seconds: not connected to a network and running as AP-only
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- Even on/off at 1HZ: connected to the configured network but no IP address (waiting on DHCP)
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- Steady on with very short off every 3 seconds: connected to the configured network with an
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IP address (esp-link shuts down its AP after 15 seconds)
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The yellow "ser" LED will blink briefly every time serial data is sent or received by the esp-link.
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Wifi configuration details
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--------------------------
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After you have serially flashed the module it will create a wifi access point (AP) with an
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SSID of the form `ESP_012ABC` where 012ABC is a piece of the module's MAC address.
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Using a laptop, phone, or tablet connect to this SSID and then open a browser pointed at
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http://192.168.4.1/, you should then see the esp-link web site.
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Now configure the wifi. The desired configuration is for the esp-link to be a
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station on your local wifi network so you can communicate with it from all your computers.
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To make this happen, navigate to the wifi page and you should see the esp-link scan
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for available networks. You should then see a list of detected networks on the web page and you
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can select yours.
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Enter a password if your network is secure (highly recommended...) and hit the connect button.
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You should now see that the esp-link has connected to your network and it should show you
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its IP address. _Write it down_. You will then have to switch your laptop, phone, or tablet
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back to your network and then you can connect to the esp-link's IP address or, depending on your
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network's DHCP/DNS config you may be able to go to http://esp-link.local
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At this point the esp-link will have switched to STA mode and be just a station on your
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wifi network. These settings are stored in flash and thereby remembered through resets and
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power cycles. They are also remembered when you flash new firmware. Only flashing `blank.bin`
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via the serial port as indicated above will reset the wifi settings.
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There is a fail-safe, which is that after a reset or a configuration change, if the esp-link
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cannot connect to your network it will revert back to AP+STA mode after 15 seconds and thus
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both present its `ESP_012ABC`-style network and continue trying to reconnect to the requested network.
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You can then connect to the esp-link's AP and reconfigure the station part.
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One open issue (#28) is that esp-link cannot always display the IP address it is getting to the browser
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used to configure the ssid/password info. The problem is that the initial STA+AP mode may use
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channel 1 and you configure it to connect to an AP on channel 6. This requires the ESP8266's AP
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to also switch to channel 6 disconnecting you in the meantime.
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Troubleshooting
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---------------
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- verify that you have sufficient power, borderline power can cause the esp module to seemingly
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function until it tries to transmit and the power rail collapses
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- check the "conn" LED to see which mode esp-link is in (see LED info above)
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- reset or power-cycle the esp-link to force it to become an access-point if it can't
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connect to your network within 15-20 seconds
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- if the LED says that esp-link is on your network but you can't get to it, make sure your
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laptop is on the same network (and no longer on the esp's network)
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- if you do not know the esp-link's IP address on your network, try `esp-link.local`, try to find
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the lease in your DHCP server; if all fails, you may have to turn off your access point (or walk
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far enough away) and reset/power-cycle esp-link, it will then fail to connect and start its
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own AP after 15-20 seconds
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Building the firmware
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---------------------
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The firmware has been built using the [esp-open-sdk](https://github.com/pfalcon/esp-open-sdk)
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on a Linux system. Create an esp8266 directory, install the esp-open-sdk into a sub-directory.
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Download the Espressif SDK (use the version mentioned in the release notes) from their
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[download forum](http://bbs.espressif.com/viewforum.php?f=5) and also expand it into a
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sub-directory. Then clone the esp-link repository into a third sub-directory.
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This way the relative paths in the Makefile will work.
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If you choose a different directory structure look at the Makefile for the appropriate environment
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variables to define.
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In order to OTA-update the esp8266 you should `export ESP_HOSTNAME=...` with the hostname or
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IP address of your module.
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Now, build the code: `make` in the top-level of esp-link.
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A few notes from others (I can't fully verify these):
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- You may need to install `zlib1g-dev` and `python-serial`
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- Make sure you have the correct version of the esp_iot_sdk
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- Make sure the paths at the beginning of the makefile are correct
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- Make sure `esp-open-sdk/xtensa-lx106-elf/bin` is in the PATH set in the Makefile
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Flashing the firmware
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---------------------
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This firmware supports over-the-air (OTA) flashing, so you do not have to deal with serial
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flashing again after the initial one! The recommended way to flash is to use `make wiflash`
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if you are also building the firmware.
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If you are downloading firmware binaries use `./wiflash`.
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`make wiflash` assumes that you set `ESP_HOSTNAME` to the hostname or IP address of your esp-link.
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You can easily do that using something like `ESP_HOSTNAME=192.168.1.5 make wiflash`.
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The flashing, restart, and re-associating with your wireless network takes about 15 seconds
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and is fully automatic. The 512KB flash are divided into two 236KB partitions allowing for new
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code to be uploaded into one partition while running from the other. This is the official
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OTA upgrade method supported by the SDK, except that the firmware is POSTed to the module
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using curl as opposed to having the module download it from a cloud server.
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If you are downloading the binary versions of the firmware (links forthcoming) you need to have
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both `user1.bin` and `user2.bin` handy and run `wiflash.sh <esp-hostname> user1.bin user2.bin`.
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This will query the esp-link for which file it needs, upload the file, and then reconnect to
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ensure all is well.
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Note that when you flash the firmware the wifi settings are all preserved so the esp-link should
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reconnect to your network within a few seconds and the whole flashing process should take 15-30
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from beginning to end. If you need to clear the wifi settings you need to reflash the `blank.bin`
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using the serial port.
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The flash configuration and the OTA upgrade process is described in more detail in [FLASH.md](FLASH.md)
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Serial bridge and connections to Arduino, AVR, ARM, LPC microcontrollers
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------------------------------------------------------------------------
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In order to connect through the esp-link to a microcontroller use port 23. For example,
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on linux you can use `nc esp-hostname 23` or `telnet esp-hostname 23`.
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You can reprogram an Arduino / AVR microcontroller by pointing avrdude at port 23. Instead of
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specifying a serial port of the form /dev/ttyUSB0 use `net:esp-link:23` with avrdude's -P option
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(where `esp-link` is either the hostname of your esp-link or its IP address).
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The esp-link detects that avrdude starts its connection with a flash synchronization sequence
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and sends a reset to the AVR microcontroller so it can switch into flash programming mode.
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You can reprogram NXP's LPC800-series and many other ARM processors as well by pointing your
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programmer similarly at the esp-link's port 23. For example, if you are using
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https://github.com/jeelabs/embello/tree/master/tools/uploader a command line like
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`uploader -t -s -w esp-link:23 build/firmware.bin` does the trick.
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The way it works is that the uploader uses telnet protocol escape sequences in order to
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make esp-link issue the appropriate "ISP" and reset sequence to the microcontroller to start the
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flash programming. If you use a different ARM programming tool it will work as well as long as
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it starts the connection with the `?\r\n` synchronization sequence.
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Note that multiple connections to port 23 can be made simultaneously. The esp-link will
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intermix characters received on all these connections onto the serial TX and it will
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broadcast incoming characters from the serial RX to all connections. Use with caution!
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Debug log
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---------
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The esp-link web UI can display the esp-link debug log (os_printf statements in the code). This
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is handy but sometimes not sufficient. Esp-link also prints the debug info to the UART where
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it is sometimes more convenient and sometimes less... For this reason three UART debug log
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modes are supported that can be set in the web UI (and the mode is saved in flash):
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- auto: the UART log starts enabled at boot and disables itself when esp-link associates with
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an AP. It re-enables itself if the association is lost.
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- off: the UART log is always off
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- on: the UART log is always on
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Note that even if the UART log is always off the bootloader prints to uart0 whenever the
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esp8266 comes out of reset. This cannot be disabled.
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Outbound TCP connections
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------------------------
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The attached micro-controller can open outbound TCP connections using a simple
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[serial protocol](https://gist.github.com/tve/a46c44bf1f6b42bc572e).
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More info and sample code forthcoming...
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Contact
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-------
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If you find problems with esp-link, please create a github issue. If you have a question, please
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use the gitter link at the top of this page.
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