AME Software: Difference between revisions

From IoT with AME
Jump to navigation Jump to search
No edit summary
No edit summary
Line 65: Line 65:


would be sent, indicating the production of two output attributes with the names "pressure" and "temperature" with numeric output format.
would be sent, indicating the production of two output attributes with the names "pressure" and "temperature" with numeric output format.
==Arduino==
Communications between Arduino and ESP8266 is via serial interface. The timing demands are high as the ESP mercilessly transmits arriving IP data at full speed. SoftwareSerial definitely is ''not'' an option. The hardware serial interface usually is used to program the Arduino, though. I use SPI programming und logging via I2C to free up the hardware interface ([[AC.programmer|details]]). And since we don't need a bootloader anymore, we gain 2kB of flash memory as well.
To avoid problems I increased the size of the receive buffer from 64 to 256 bytes. This does eat RAM memory, but makes for safer operation. Your mileage may vary: if your messages are short 64 Bytes is just fine.
To adjust the receive buffer size, add the line
  #define SERIAL_RX_BUFFER_SIZE 256
in HardwareSerial.h before the first #if. In newer installations of the Arduino IDE on Windows the file does not reside south of the program folder, but is located in AppData/Local, in example
  C:\Users\<username>\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.16\cores\arduino


[[The AME Stack]]
[[The AME Stack]]
__NOTOC__
__NOTOC__

Revision as of 10:15, 23 June 2018

The AME Stack

AME Stack (Software)

Class structure (operations incomplete)


AC_ESP8266

AC_ESP8266 provides access to the ESP8266 on C++ level, no more, no less. It uses two (blowing my own horn) clever functions to compose commands and to parse responses based on pattern expansion/ matching.

The buffer used for command assembly and response parsing is the only one in the whole class. Writing and reading IP data is performed streaming. Callbacks announce the arrival of data and loss of connection.

Regarding command assembly and response parsing I think even that could be migrated to streaming mode, though pattern matching would be not that easy, I guess.

AC_TCP_ESP8266

AC_TCP_ESP8266 provides streaming TCP functionality based on - you guessed it - the ESP8266. It deals with loss of TCP and WLAN connectivity.

It does what is required to get the ESP working again, which, frankly sometimes is not easy and a pain in the back. This includes resetting the chip via software and - optionally - hardware (it uses the reset pin of the ESP).

If you want to, it even can turn the ESP off and on again. I think that does exhaust all options available.

AC_MTTQ

AC_MTTQ provides standard MQTT functions with QoS 0 or 1. More honestly QoS "0.5" as it properly produces ACK messages to the broker, but arriving ACKs are discarded and missing ACKs don't prompt retries).

Unlike other libaries AC_MQTT does not get unhappy if a ping response gets lost while performing publish and subscribe operations.

AC_IoT/ Devices

Devices are derived from AC_IoT. AC_IoT provides convenience on device level with concepts such as centrally configured device name and MQTT-ID that get used wherever appropriate.

In example, a device with MQTT-ID "garden01" uses "garden01" as a prefix for topics in publications and subscriptions of its capabilities.

When the MQTT connection is established AC_IoT reports the version of the IoT framework, the device version, the IP and MAC addresses, and the number of connect attempts.

In example, the messages

  • "garden01/versionIoT 1.038"
  • "garden01/version 1.010"
  • "garden01/connectAttempts 12"
  • "garden01/ip 192.168.2.76"
  • "garden01/mac 5d:de:ad:be:ef"

would be sent.

Capabilities

Capabilities can easily be added to a device. For a gardening system you maybe add capabilities "temperature", "spoil moisture", "rain", and "relay" (ie, to turn an irrigation system on and off).

A capability encapsulates hardware intricacies, possess a built-in name, and provides configuration options such as a capability ID (a number), update intervals, I/O pins and so on.

In example, a capability encapsulating a BMP280 air pressure and temperature sensor with the built-in name "pressure" has been assigned capability ID "1". The capability will produce publications at a configurable interval using the name of the device, the name of the capability, the capability ID, and the attribute name.

Building on the example above, publications would use the topics

  • "garden01/pressure01/pressure" and
  • "garden01/pressure01/temperature"

Additionally, Capabilities report their version and input and output parameters when the MQTT connection is established. In example, the messages

  • "garden01/pressure01/version 1.001"
  • "garden01/pressure01/capa01 <pressure:<d>" and
  • "garden01/pressure01/capa02 <temperature:<d>"

would be sent, indicating the production of two output attributes with the names "pressure" and "temperature" with numeric output format.

Arduino

Communications between Arduino and ESP8266 is via serial interface. The timing demands are high as the ESP mercilessly transmits arriving IP data at full speed. SoftwareSerial definitely is not an option. The hardware serial interface usually is used to program the Arduino, though. I use SPI programming und logging via I2C to free up the hardware interface (details). And since we don't need a bootloader anymore, we gain 2kB of flash memory as well.

To avoid problems I increased the size of the receive buffer from 64 to 256 bytes. This does eat RAM memory, but makes for safer operation. Your mileage may vary: if your messages are short 64 Bytes is just fine.

To adjust the receive buffer size, add the line

 #define SERIAL_RX_BUFFER_SIZE 256

in HardwareSerial.h before the first #if. In newer installations of the Arduino IDE on Windows the file does not reside south of the program folder, but is located in AppData/Local, in example

 C:\Users\<username>\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.16\cores\arduino

The AME Stack