ESP8266 Light Alarm Clock

Being woken up by a loud alarm sound, trying to find the dismiss button on your phone is propably one of the most disruptive ways to start your day. A much more convenient alternative is to slowly dim up the room light to simulate the sunrise. This project is an implementation of this alternative alarm clock.

Hardware

The alarm clock is based on the ESP-01 WiFi module with the ESP8266 WiFi chip. GPIO2 of the ESP-01 is simply connected to a transistor that controls an LED stripe (could be any other load). A simple RC low pass filter makes the transition between different light intensities (achieved using PWM) smooth, the capacitor and resistor values in the above diagram really depend on how smooth you want these transitions to be and on your type of MOSFET. The 3.3V for the ESP-01 can be provided by any 3.3V LDO, such as the LF33CV or LF33CDT. The default 512KB flash chip is enough for storing all the software and alarm times.

Software

Please make sure to clone using --recursive (in order to download the libesphttpd submodule):

git clone --recursive https://github.com/Jeija/esp8266-light-alarmclock

Configuration

• By default esp8266-light-alarmclock uses TimeZoneDB to retrieve the current time in your timezone. You will need to register with timezonedb in order to get your own API key and provide this key to esp8266-light-alarmclock when compiling.
• To set your timezone or switch to another time API (other than https://timezonedb.com), edit #define TIMEZONE "Europe/Berlin" and #define TIMEZONEDB_URL ... in src/user_config.h. If you want to switch to a different time provider API that returns an ISO-formatted date string (e.g. 2017-01-01 00:00:00) in a JSON object, you only need to set TIMEZONEDB_FIELD to the JSON field that contains this time string. Otherwise, you have to modify http_callback_time and parse your custom time format.
• You can either set a static IP Address or tell the clock to use DHCP. In order to use a dynamic address, comment out #define USE_STATIC in src/user_config.h. Otherwise, adapt these values in src/user_config.h to your network:

#define USE_STATIC
#define IP_ADDR	"192.168.0.50"
#define IP_GATEWAY "192.168.0.2"
#define IP_SUBNET "255.255.0.0"

• If you want to change the light dimming behaviour when an alarm occurs, edit the following defines in src/user_config.h: ALARM_HOLD_DURATION (time that the light stays on at full brightness after dimming up), ALARM_DIM_DURATION (time that dimming up takes), ALARM_DIM_INTERVAL (interval in which the clock checks whether increasing the light intensity is necessary when dimming up), ALARM_DIM_START (intensity at which dimming starts, then linear interpolation until ALARM_DIM_STOP is used), ALARM_DIM_STOP (intensity at which dimming ends, then jumps to ALARM_DIM_FINAL intensity and holds it), ALARM_DIM_FINAL (intensity that is held for ALARM_HOLD_DURATION seconds)

Compilation

In order to compile esp8266-light-alarmclock, you need a fully set up esp-open-sdk, tested with Espressif's IoT SDK version 2.0. Make sure the Xtensa binaries are in your PATH variable and edit the Makefile so that it contains the correct SDK_DIR as well as your serial port configuration and flash chip properties.

You have to set your WiFi SSID and passphrase as well as your TimeZoneDB API key (see section Configuration) at compile time. In order to do that, execute

make WIFI_PASS="YOUR_PASSPHRASE" WIFI_SSID="YOUR_SSID" TIMEZONEDB_KEY="1234ABCD1234"

You can then proceed to flash the image to your ESP8266 with make flash.

Description

• The software acts as an HTTP server. You can access the alarm clock's site at its IP, Port 80. There you can manually set the light intensity or add and remove (up to 21) alarm times. The website is optimized for mobile browsers.
• The software also contains an HTTP client that connects up to http://www.timeapi.org to retrieve the current time in your timezone. But even if your network connection happens to fail sometimes, the internal clock will keep going. This could potentially be replaced with NTP.
• Alarm times that are set on the webpage are saved to RAM and Flash so that even after a power failure the clock will remember when to wake you up.
• Shortly after the alarm times, the light will slowly dim up. If, however, you set the light's brightness manually, this will override the dimming process.

Attribution

• Compile using pfalcon's esp-open-sdk
• Makes use of Spritetm's wonderful libesphttpd / GitHub mirror
• Includes (a slightly modified version of) caerbannog's esphttpclient
• Uses http://www.timeapi.org as an easy way to synchronize network time. Can be modified to use similar services instead.