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105 lines
4.9 KiB
105 lines
4.9 KiB
ESP-LINK
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========
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This firmware implements a transparent bridge between Wifi and serial using an ESP8266 module.
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It also provides support for flash-programming Arduino/AVR microcontrollers as well as
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LPC800-series ARM microcontrollers via the ESP8266.
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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.
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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.
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The expected 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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Initial flashing
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----------------
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If you want to simply flash the provided firmware binary, you can use your favorite
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ESP8266 flashing tool and flash the following:
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- `boot_v1.3(b3).bin` from the official `esp_iot_sdk_v1.0.1` to 0x00000
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- `blank.bin` from the official SDK to 0x7e000
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- `./firmware/user1.bin` to 0x01000
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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.
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Wifi configuration
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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://192.168.0.1, you should them see the esp-link web site.
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Now configure the wifi. The typical desired configuration is for the esp-link to be a
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station on your local wifi network so can communicate with it from all your computers.
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To make this happen, navigate to the wifi page and hit the "change to STA+AP mode" button.
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This will cause the esp8266 to restart and yo will have to wait 5-10 seconds until you can
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reconnect to the ESP_123ABC wifi network and refres the wifi settings page.
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At this point you should see a list of detected networks on the web page and you can select
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yours. Enter a password if your network is secure (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 and then follow the provided link (you may have to switch your
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laptop, phone, or tablet back to your network before you can actually connect).
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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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as indicated above will reset the wifi settings.
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There is a fail-safe, which is that after a reset (need details) the esp-link will revert
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back to AP+STA mode and thus both present its ESP_012ABC-style network and try to connect to
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the requested network, which will presumably not work or it wouldn't be in fail-safe mode
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in the first place. You can then connect to the network and reconfigure the station part.
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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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You probably also need an UNIX-like system.
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To manage the paths to all this, you can source a small shell fragment into your current session. For
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example, I source a file with these contents:
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export PATH=${PWD}/esp-open-sdk/xtensa-lx106-elf/bin:$PATH
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export SDK_BASE=${PWD}/esp-open-sdk/sdk
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export ESPTOOL=${PWD}/esptool/esptool
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export ESPPORT=/dev/ttyUSB0
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export ESPBAUD=460800
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Actual setup of the SDK and toolchain is out of the scope of this document, so I hope this helps you
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enough to set up your own if you haven't already.
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If you have that, you can clone out the source code:
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git clone http://github.com/jeelabs/esp-link
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This project makes use of heatshrink, which is a git submodule. To fetch the code:
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cd esphttpd
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git submodule init
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git submodule update
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Now, build the code:
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make
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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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which assumes that you set ESP_HOSTNAME to the hostname or IP address of your esp-link
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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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