iot-temp-sensors

atmega328 + onewire ds18b20 + ethernet enc28j60/w5500

• features
• prerequisites
• config
• debugging
• api
• sketch size
• security considerations

features

• easy customization through direct index.htm and app.js editing and debugging locally
• automatic compilatio of index.htm.h and app.js.h to be included as flash string
• alloc automatically a backlog of temperature recording based upon available ram

prerequisites

• iot-atmega328p-eth
• PinChangeInterrupt

config

• ( see prerequisites prj )
• disable ENABLE_CORS in production
• set temperature device id to add a description (optional) in app.js

debugging

• start code . from sketch folder
• program the chip ctrl+shift+p through usbasp programmer ( before apply a ctrl+alt+r to invoke prebuild gen-h )
• drag index.htm and app.js into code
• config app.js
  • tune baseurl
• double click index.htm from file manager to open in a browser
• now webpage talk to atmega webapi through enc28j60 ( can use F12 and set some breakpoints from browser, may need useful to click on browser pretty button to format code because its minified )
• note : modified app.js and index.htm will compiled into flash automatically through prebuild utility gen-h

api

address	content type	result example
/tempdevices	json	{"tempdevices":["28886f5a050000dd","2865e05a0500001a","28af8123070000e2"]}
/temp/id	text	19.562500
/info	json	{"freeram":187, "history_size":123, "history_interval_sec":10}
/temphistory	json	[{"28886f5a050000dd":[20,20,20,20,20,20,20,20,20,20,21,24,25,27,28]},{"2865e05a0500001a":[20,20,20,20,20,20,20,20,20,20,20,20,20,20,20]},{"28af8123070000e2":[21,21,21,21,21,21,21,21,21,21,21,21,21,21,21]}]
/app.js	js	content of app.js
/	html	content of index.htm

sketch size

serial debug included

ENC28J60 (udp disabled)

• UIP_CONF_UDP=0 in UIPEthernet/utility/uipethernet-conf.h

Sketch uses 30606 bytes (93%) of program storage space. Maximum is 32768 bytes.
Global variables use 1308 bytes (63%) of dynamic memory, leaving 740 bytes for local variables. Maximum is 2048 bytes.

W5500

Sketch uses 27076 bytes (82%) of program storage space. Maximum is 32768 bytes.
Global variables use 702 bytes (34%) of dynamic memory, leaving 1346 bytes for local variables. Maximum is 2048 bytes.

external interrupt push notification

if want to use the device to push a notification

• in Config.h
  • ensure USE_EXTERNAL_INTERRUPT defined
  • change if needed used pin EXTERNAL_INTERRUPT_PIN ( see atmega pinmapping )
  • define header file

#define PUSHINGBOX_IP 213,186,33,19
#define PUSHINGBOX_HOSTNAME "api.pushingbox.com"
#define PUSHINGBOX_QUERY "/pushingbox?devid=xxx"

security considerations

• see prerequisite considerations
• ENABLE_CORS even disabled not imply any check at server(atmega)-side so effectively a non-browser request can execute request from any crossing domain; can mitigate wrapping with nginx