See the full docs! And also see this on git!
This project tends to implement:
- ESP8266 module messaging from AVR controller
- Basic Http request + JSON parsing
- LCD support
Because of the microcontroller exercises we did on our studies.
- Boots up (if you press any key) the avr enters
settings mode and asks for wifi creditentials
-
If no key was pressed during boot then normal procedure takes place
-
AVR tries to connect to the wifi
-
Then connects to
openweathermap.com -
Asks politely for weather data for
Warsaw -
Then fetches
JSONwith the most trivial ways -
Displays the data
-
And sometimes refreshes the collected data :)
The AVR connections are basic and listed below:
'ATMEGA32' PA0 -> D4 'LCD'
'ATMEGA32' PA1 -> D5 'LCD'
'ATMEGA32' PA2 -> D6 'LCD'
'ATMEGA32' PA3 -> D7 'LCD'
'ATMEGA32' PA4 -> RS 'LCD'
'ATMEGA32' PA5 -> RW 'LCD'
'ATMEGA32' PA6 -> E 'LCD'
'ATMEGA32' RXD -> TX 'ESP8266'
'ATMEGA32' TXD -> RX 'ESP8266'
'ESP8266' EN -> VCC 'ESP8266'And of course V0, VCC, GND, VSS, VDD, A, K but they are trivial.
And not mentioned in layout two buttons for settings screen:
'ATMEGA32' PD6 -(BUTTON)-> GND
'ATMEGA32' PD7 -(BUTTON)-> GNDIn settings mode:
-
PD6is used have next character functionality. -
PD7changes current character.
Schematic of connections (pretty small - try to enlarge with zooming hand):
Notice:
The ESP8266 module was connected to the 5V USB plug.
The module is designed to work for 3V but working on higher
voltage is possible (as demonstrated in this case).
It's straightforward method and in normal conidtions you should redesign scheme a little and provide 3V voltage source for your wifi module.
You will probably need logic level shifting
form 5V (atemga) to 3V (esp8266) or you can just run atmega on 3V
(notice that LCD needs standard 5V anyway!)
You can mount the wires propably on pcb plate I used universal brakboard that does not require soldering but it's rather a messy pile of cables, huh!
Warnning!
Before building make sure all it's configured correctly (see configuration for more details)!
To build the project do the following:
-
Create release folder e.g.
mkdir release -
Go into that folder
cd release -
Run CMAKE to generate needed makefiles
cmake .. -
Build app using make
make -
Optionally update documentation throught
make doc -
Optionally setup manually the needed fuse bits using
avrdude! -
Flash controller with
make upload -
Optionally clean build with
make clean
Before continouing make sure that USSID and PASSWD Variables
in src/main.c are configured to use with your wifi access point.
Then make sure that APIKEY in line with wifi_send is matching
apikey for your openweathermap account.
And the url is for location desired by you.
See openweathermap api documentation for more details :)
The main controller config is placed in CMakeLists.txt file.
Please change these as you wish:
# Variables regarding the AVR chip
set(MCU atmega32)
set(F_CPU 8000000)
set(BAUD 9600)
set(PROG_TYPE usbasp)
set(PROG_ARGS )BAUD is not really needed and PROG_ARGS are additional paramters for avrdude.
Basic example config for Atmega328P-PU running (by default) at 1MHz:
# Variables regarding the AVR chip
set(MCU atmega328p)
set(F_CPU 1000000)
set(BAUD 2400)
set(PROG_TYPE usbasp)
set(PROG_ARGS )This snippet presents piece of source code from main.c
(and is good introduction to the project insides as well as wifi.h module):
// Handle ESP8266 events
void wifi_event_handler(int event, const char* input, const int len) {
switch(event) {
case WIFI_EVENT_ANY: {
//
// You can display the input
// To provide debug info
// This kind of event (ANY)
// is called for any event
//
return;
} break;
case WIFI_EVENT_ERROR: {
// We got error!
} break;
// ESP8266 is not responding
case WIFI_EVENT_TIMEOUT: {
// We got timeout!
} break;
// Wifi was connected
case WIFI_EVENT_WIFI_CONNECTED: {
// We are conneted to the access point!
} break;
// Wifi was disconnected
case WIFI_EVENT_WIFI_DISCONNECTED: {
// We are disconneted to the access point!
} break;
// Connect to host
case WIFI_EVENT_CONNECTED: {
// We are connected to the ip/url specified earlier throug wifi_link_open
} break;
// Host sends data
case WIFI_EVENT_DATA: {
//
// Look for JSON data in response
//
search_json(weather_descr, input, "description");
search_json(weather_name, input, "name");
search_json(weather_data_buf, input, "humidity");
sscanf(weather_data_buf, "%lf", &weather_humidity);
search_json(weather_data_buf, input, "pressure");
sscanf(weather_data_buf, "%d", &weather_pressure);
search_json(weather_data_buf, input, "temp");
sscanf(weather_data_buf, "%lf", &weather_temp);
// We do not need this connection anymore
wifi_link_close();
// Format received data
sprintf(info1, "%s Weather:", weather_name);
sprintf(info2, "%s | Temp: %.1lf C | Humidity: %.0lf %% | Pressure: %d HPa", weather_name, weather_temp-273.15, weather_humidity, weather_pressure );
//
// Display data continously in text shifting manner
//
int shift = 0;
const int info_len = strlen(info2);
int cycles = 0;
while(1) {
lcd_clrscr();
lcd_gotoxy(0, 0);
lcd_nputs(info1, 16);
lcd_gotoxy(0, 1);
lcd_nputs(info2+shift, 16);
_delay_ms(500);
++shift;
if(shift > info_len - 4) {
shift = 0;
++cycles;
}
//
// End - return to main and then prepare next fetch request
//
if(cycles > 15) break;
}
lcd_nputs("Update...", 16);
lcd_clrscr();
} break;
}
}
int main(void) {
// Init UART
uart_init(UART_BAUD_SELECT(2400, F_CPU));
// Init buttons
//
// ...
//
// Init LCD
lcd_init(LCD_DISP_ON);
lcd_gotoxy(0, 0);
lcd_clrscr();
// Init wifi and connect to the desired network
lcd_clrscr();
lcd_puts("Initializing...");
_delay_ms(1000);
wifi_init();
//
// Check if any button was pressed
// then go into settings mode :)
//
//
// ...
//
//
// Normal boot sequence
//
normal_boot:
// Display greeting on lcd
lcd_puts("Hello");
_delay_ms(1000);
lcd_clrscr();
_delay_ms(1500);
lcd_clrscr();
lcd_puts("Conecting...");
_delay_ms(1000);
//
// Display USSID/PASSWD data on the screen
//
lcd_clrscr();
lcd_puts("ID: ");
lcd_puts(USSID);
lcd_puts("\nPASS: ");
lcd_puts(PASSWD);
_delay_ms(1500);
// Try to connect to the access point
wifi_connect(USSID, PASSWD);
while(1) {
// To make sure nothing dumb trash does not come
// through UART interface
uart_flush();
// Connect to openweathermap
wifi_link_open("TCP", "api.openweathermap.org", 80);
// Request data from REST api
wifi_send("GET /data/2.5/weather?q=warsaw&APPID=cf24c94ac2550178e2ea4e970cd0f416 HTTP/1.1\r\nHost: api.openweathermap.org\r\nConnection: keep-alive\r\nCache-Control: max-age=0\r\n\r\n\r\n");
// Wifi functions will call wifi_event_handler function on any event (it's callback function)
}
return 0;
}