Steve Karg
118 lines
5.2 KiB
Markdown
118 lines
5.2 KiB
Markdown
### BACnet MS/TP on Arduino Uno R3 Platform - Atmega328p
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The Arduino Uno R3 platform for this example uses the following peripherals:
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1) USB bootloader using AVR-119 protocol
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2) Arduino Uno V3 I/O to BACnet Objects map - see below
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3) Arduino Uno V3 compatible RS485 shield (DFR0259)
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### Arduino Uno V3 Pin Mapping
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| ATmega328p | Arduino | RS485 DFR0259 | BACnet Object |
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|:------------|:------------|:---------------|:----------------|
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| NC | NC | | |
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| +5V | IOREF | | |
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| RESET | RESET | RST BUTTON | |
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| +3V3 | +3V3 | | |
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| +5V | +5V | +5V | |
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| GND | GND | GND | |
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| GND | GND | GND | |
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| VIN | VIN | | |
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| ADC0/PC0 | A0 | | AV-0 Millivolts |
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| ADC1/PC1 | A1 | | AV-1 Millivolts |
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| ADC2/PC2 | A2 | | AV-2 Millivolts |
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| ADC3/PC3 | A3 | | AV-3 Millivolts |
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| ADC4/PC4 | A4* | | |
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| ADC5/PC5 | A5* | | |
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| ADC5/PC5 | SCL* | I2C | |
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| ADC4/PC4 | SDA* | I2C | |
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| AVDD | AREF | | |
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| GND | GND | | |
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| SCK/PB5 | D13 | LED-L ANODE (+)| BV-99 (output) |
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| MISO/PB4 | D12 | | BV-9 (output) |
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| MOSI/PB3 | D11 | | BV-8 (output) |
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| SS/PB2 | D10 | | BV-7 (output) |
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| OC1/PB1 | D9 | | BV-6 (output) |
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| ICP/PB0 | D8 | | BV-5 (output) |
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| AIN1/PD7 | D7 | | BV-4 (input) |
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| AIN0/PD6 | D6 | | BV-3 (input) |
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| T1/PD5 | D5 | | BV-2 (input) |
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| T0/PD4 | D4 | | BV-1 (input) |
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| INT1/PD3 | D3 | | BV-0 (input) |
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| INT0/PD2 | D2 | CE DE /RE RTS | RS485 |
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| TXD/PD1 | D1/Tx** | TXD | RS485 |
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| RXD/PD0 | D0/Rx** | RXD | RS485 |
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\* ADC4/PC4: A4 and SDA are shared I/O
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\* ADC5/PC5: A5 and SCL are shared I/O
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\** shared with Uno R3 USB Tx/Rx. DFR0259 switch ON to disable.
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### Building this Project
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#### GNU Makefile
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There is a GNU Makefile that uses avr-gcc and avr-libc to build the project.
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avrdude can be used to program the Arduino Uno R3 board via USB.
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The GNU Makefile is used in the continuous integration pipeline to validate
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the build is not broken. The Makefile is called from an Ubuntu image
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container after installing the necessary tools:
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sudo apt-get update -qq
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sudo apt-get install -qq build-essential
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sudo apt-get install -qq gcc-avr avr-libc binutils-avr avrdude
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To add the build and debug tools to MinGW64 environment:
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pacman --noconfirm -S mingw-w64-x86_64-gcc-avr
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pacman --noconfirm -S mingw-w64-x86_64-avr-libc
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pacman --noconfirm -S mingw-w64-x86_64-binutils-avr
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pacman --noconfirm -S mingw-w64-x86_64-avrdude
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The build sequence is usually:
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make clean all
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The Makefile includes a recipe to use avrdude to program the Uno R3 via USB
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make install
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#### Board diagnostics and configuration
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| BACnet Object | Description | Default | R/W |
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|:------------------|:-----------------|:---------------|:------|
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| AV-92 | Device ID | 260123 | R/W |
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| AV-93 | MS/TP bitrate | 38400 bps | R/W |
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| AV-94 | MS/TP MAC | 123 | R/W |
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| AV-95 | MS/TP Max Manager| 127 | R/W |
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| AV-96 | MCU Frequency | F_CPU | R |
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| AV-97 | CStack Size | 0 | R |
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| AV-98 | CStack Unused | 0 | R |
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| AV-99 | Uptime | 0 | R |
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##### Shield option
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The DFR0259 shield for RS485 was used, but any RS485 circuit could be
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attached to the Arduino Uno R3 using the same pins for Tx, Rx, CE RE/DE RTS.
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The MS/TP MAC address, bitrate, and max-manager are stored in EEPROM.
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### BACnet Capabilities
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The BACnet Capabilities include WhoIs, I-Am, ReadProperty, and
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WriteProperty support. The BACnet objects include a Device object,
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10 Binary Value objects, and 10 Analog Value objects. An GPIO output
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is controlled by Binary Value object instance 0. All required object
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properties can be retrieved using ReadProperty. The Present_Value
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property of the Analog Value and Binary Value objects can be
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written using WriteProperty. The Object_Identifier, Object_Name,
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Max_Info_Frames, Max_Master, and baud rate (property 9600) of the
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Device object can be written using WriteProperty.
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