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esp-httpd README |
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ESP8266 - Bridge |
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================ |
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This is a small but powerful webserver for ESP8266(EX) chips. Included is an example of how |
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to make a module that can have the AP it connects to configured over a webbrowser. |
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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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ABOUT THE WEBSERVER |
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LPC800-series ARM microcontrollers via the ESP8266. |
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The Good (aka: what's awesome) |
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The firmware includes a tiny HTTP server based on |
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- Supports multiple connections, for eg simultaneous html/css/js/images downloading |
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[esphttpd](http://www.esp8266.com/viewforum.php?f=34) |
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- Static files stored in flash, in an (optionally compressed) RO filesystem |
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with a simple web interface. |
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- Pluggable using external cgi routines |
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- Simple template engine for mixed c and html things |
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Hardware info |
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------------- |
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The Bad (aka: what can be improved) |
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This firmware is designed for esp8266 modules which have most esp I/O pins available. |
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- Not built for speediness, although it's reasonable fast. |
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The expected connections are: |
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- Built according to what I remember of the HTTP protocol, not according to the |
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- URXD: connect to TX of microcontroller |
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RFCs. Should work with most modern browsers, though. |
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- UTXD: connect to RX of microcontroller |
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- No support for https. |
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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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The Ugly (aka: bugs, misbehaviour) |
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- GPIO0: optionally connect green "conn" LED to 3.3V (indicates wifi status) |
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- Possible buffer overflows (usually not remotely exploitable) due to no os_snprintf |
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- GPIO2: optionally connect yellow "ser" LED to 3.3V (indicates serial activity) |
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This can be theoretically remedied by either Espressif including an os_snprintf in |
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If you are using an FTDI connector, GPIO12 goes to DTR and GPIO13 goes to CTS |
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their libs or by using some alternate printf lib, like elm-chans xprintf |
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Initial flashing |
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ABOUT THE EXAMPLE |
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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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When you flash the example into an ESP8266(EX) module, you get a small webserver with a few example |
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ESP8266 flashing tool and flash the following: |
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pages. If you've already connected your module to your WLAN before, it'll keep those settings. When |
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- `boot_v1.3(b3).bin` from the official `esp_iot_sdk_v1.0.1` to 0x00000 |
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you haven't or the settings are wrong, keep GPIO0 for >5 seconds. The module will reboot into |
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- `blank.bin` from the official SDK to 0x7e000 |
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its STA+AP mode. Connect a computer to the newly formed access point and browse to |
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- `./firmware/user1.bin` to 0x01000 |
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http://192.168.4.1/wifi in order to connect the module to your WiFi network. The example also |
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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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allows you to control a LED that's connected to GPIO2. |
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modules appear to have. |
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BUILDING EVERYTHING |
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Wifi configuration |
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--------------------- |
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For this, you need an environment that can compile ESP8266 firmware. Environments for this still |
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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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are in flux at the moment, but I'm using esp-open-sdk: https://github.com/pfalcon/esp-open-sdk . |
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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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You probably also need an UNIX-like system; I'm working on Debian Linux myself. |
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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 esp8266-bridge web site. |
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Now configure the wifi. The typical desired configuration is for the esp-bridge 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-bridge 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-bridge 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-bridge 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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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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example, I source a file with these contents: |
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@ -49,7 +81,7 @@ Actual setup of the SDK and toolchain is out of the scope of this document, so I |
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enough to set up your own if you haven't already. |
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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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If you have that, you can clone out the source code: |
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git clone http://git.spritesserver.nl/esphttpd.git/ |
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git clone http://github.com/jeelabs/esp-bridge |
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This project makes use of heatshrink, which is a git submodule. To fetch the code: |
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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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cd esphttpd |
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@ -59,28 +91,15 @@ git submodule update |
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Now, build the code: |
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Now, build the code: |
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make |
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make |
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Flash the code happens in 2 steps. First the code itself gets flashed. Reset the module into bootloader |
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Flashing the firmware |
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mode and enter 'make flash'. You may want to reset and re-enter the bootloader halfway (at 'sleep 3') for |
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--------------------- |
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the 2nd part of this flash to work. |
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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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The 2nd step is to pack the static files the webserver will serve and flash that. Reset the module into |
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which assumes that you set ESP_HOSTNAME to the hostname or IP address of your esp-bridge. |
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bootloader mode again and enter 'make htmlflash'. |
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The flashing, restart, and re-associating with your wireless network takes about 15 seconds |
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You should have a working webserver now. |
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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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WRITING CODE FOR THE WEBSERVER |
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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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...errm... to be done. For now, look at the examples. Hey, you probably managed to find out how |
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the SDK works, this shouldn't be too hard :P |
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CHANGE FROM SDK 0.9.3 (and earlier) TO SDK 0.9.4 (and later): |
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Change all occurences of |
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espconn_sent(connData->conn, (uint8 *)buff, len); |
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to |
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httpdSend(connData, buff, len) |
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please. The reason for this is that you can't do multiple espconn_sent calls serially anymore, so |
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httpd needs to buffer the writes now. This is only needed in your own code; the code that comes |
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with httpd already has this changed. |
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